The Latest Celestial Discovery by Kepler's Successor...

NASA GSFC

NASA’s TESS Spots Record-Breaking Stellar Triplets (News Release - October 2)

Professional and amateur astronomers teamed up with artificial intelligence to find an unmatched stellar trio called TIC 290061484, thanks to cosmic “strobe lights” captured by NASA’s TESS (Transiting Exoplanet Survey Satellite).

The system contains a set of twin stars orbiting each other every 1.8 days, and a third star that circles the pair in just 25 days. The discovery smashes the record for shortest outer orbital period for this type of system, set in 1956, which had a third star orbiting an inner pair in 33 days.

“Thanks to the compact, edge-on configuration of the system, we can measure the orbits, masses, sizes and temperatures of its stars,” said Veselin Kostov, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the SETI Institute in Mountain View, California. “And we can study how the system formed and predict how it may evolve.”

A paper, led by Kostov, describing the results was published in The Astrophysical Journal on October 2.

Flickers in starlight helped reveal the tight trio, which is located in the constellation Cygnus. The system happens to be almost flat from our perspective. This means that the stars cross right in front of, or eclipse, each other as they orbit.

When that happens, the nearer star blocks some of the farther star’s light.

Using machine learning, scientists filtered through enormous sets of starlight data from TESS to identify patterns of dimming that reveal eclipses. Then, a small team of citizen scientists filtered further, relying on years of experience and informal training to find particularly interesting cases.

These amateur astronomers, who are co-authors on the new study, met as participants in an online citizen science project called Planet Hunters, which was active from 2010 to 2013. The volunteers later teamed up with professional astronomers to create a new collaboration called the Visual Survey Group, which has been active for over a decade.

“We’re mainly looking for signatures of compact multi-star systems, unusual pulsating stars in binary systems, and weird objects,” said Saul Rappaport, an emeritus professor of physics at MIT in Cambridge. Rappaport co-authored the paper and has helped lead the Visual Survey Group for more than a decade. “It’s exciting to identify a system like this because they’re rarely found, but they may be more common than current tallies suggest.”

Many more likely speckle our galaxy, waiting to be discovered.

Partly because the stars in the newfound system orbit in nearly the same plane, scientists say that it’s likely very stable despite their tight configuration (the trio’s orbits fit within a smaller area than Mercury’s orbit around the Sun). Each star’s gravity doesn’t perturb the others too much, like they could if their orbits were tilted in different directions.

But while their orbits will likely remain stable for millions of years, “no one lives here,” Rappaport said. “We think the stars formed together from the same growth process, which would have disrupted planets from forming very closely around any of the stars.” The exception could be a distant planet orbiting the three stars as if they were one.

As the inner stars age, they will expand and ultimately merge, triggering a supernova explosion in around 20 to 40 million years.

In the meantime, astronomers are hunting for triple stars with even shorter orbits. That’s hard to do with current technology, but a new tool is on the way.

Images from NASA’s upcoming Nancy Grace Roman Space Telescope will be much more detailed than TESS’s. The same area of the sky covered by a single TESS pixel will fit more than 36,000 Roman pixels. And while TESS took a wide, shallow look at the entire sky, Roman will pierce deep into the heart of our galaxy where stars crowd together, providing a core sample rather than skimming the whole surface.

“We don’t know much about a lot of the stars in the center of the galaxy except for the brightest ones,” said Brian Powell, a co-author and data scientist at Goddard. “Roman’s high-resolution view will help us measure light from stars that usually blur together, providing the best look yet at the nature of star systems in our galaxy.”

And since Roman will monitor light from hundreds of millions of stars as part of one of its main surveys, it will help astronomers find more triple star systems in which all the stars eclipse each other.

“We’re curious why we haven’t found star systems like these with even shorter outer orbital periods,” said Powell. “Roman should help us find them and bring us closer to figuring out what their limits might be.”

Roman could also find eclipsing stars bound together in even larger groups — half a dozen, or perhaps even more all orbiting each other like bees buzzing around a hive.

“Before scientists discovered triply eclipsing triple star systems, we didn’t expect them to be out there,” said co-author Tamás Borkovits, a senior research fellow at the Baja Observatory of The University of Szeged in Hungary. “But once we found them, we thought, well why not? Roman, too, may reveal never-before-seen categories of systems and objects that will surprise astronomers.”

Source: NASA.Gov

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NASA GSFC

A Prolific Space Telescope Makes More Celestial Discoveries 5 Years After It Retired...

NASA / Daniel Rutter

Scorching, Seven-Planet System Revealed by New Kepler Exoplanet List (News Release - November 2)

A system of seven sweltering planets has been revealed by continued study of data from NASA’s retired Kepler space telescope: Each one is bathed in more radiant heat from their host star per area than any planet in our solar system. Also unlike any of our immediate neighbors, all seven planets in this system, named Kepler-385, are larger than Earth but smaller than Neptune.

It is one of only a few planetary systems known to contain more than six verified planets or planet candidates. The Kepler-385 system is among the highlights of a new Kepler catalog that contains almost 4,400 planet candidates, including more than 700 multi-planet systems.

“We’ve assembled the most accurate list of Kepler planet candidates and their properties to date,” said Jack Lissauer, a research scientist at NASA’s Ames Research Center in California’s Silicon Valley and lead author on the paper presenting the new catalog. “NASA’s Kepler mission has discovered the majority of known exoplanets, and this new catalog will enable astronomers to learn more about their characteristics.”

At the center of the Kepler-385 system is a Sun-like star about 10% larger and 5% hotter than the Sun. The two inner planets, both slightly larger than Earth, are probably rocky and may have thin atmospheres.

The other five planets are larger – each with a radius about twice the size of Earth’s – and expected to be enshrouded in thick atmospheres.

The ability to describe the properties of the Kepler-385 system in such detail is testament to the quality of this latest catalog of exoplanets. While the Kepler mission’s final catalogs focused on producing lists optimized to measure how common planets are around other stars, this study focuses on producing a comprehensive list that provides accurate information about each of the systems, making discoveries like Kepler-385 possible.

The new catalog uses improved measurements of stellar properties and calculates more accurately the path of each transiting planet across its host star. This combination illustrates that when a star hosts several transiting planets, they typically have more circular orbits than when a star hosts only one or two.

Kepler’s primary observations ceased in 2013 and were followed by the telescope’s extended mission, called K2, which continued until 2018. The data Kepler collected continues to reveal new discoveries about our galaxy.

After the mission already showed us there are more planets than stars, this new study paints a more detailed picture of what each of those planets and their home systems look like, giving us a better view of the many worlds beyond our solar system.

The research article, “Updated Catalog of Kepler Planet Candidates: Focus on Accuracy and Orbital Periods” is forthcoming in The Journal of Planetary Science.

Source: NASA.Gov

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NASA / Daniel Rutter

Hubble's Successor Finds More Evidence of a Potentially Habitable Exoplanet...

NASA, CSA, ESA, J. Olmsted (STScI), Science: N. Madhusudhan (Cambridge University)

Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18 b (News Release)

A new investigation with NASA’s James Webb Space Telescope into K2-18 b, an exoplanet 8.6 times as massive as Earth, has revealed the presence of carbon-bearing molecules including methane and carbon dioxide. Webb’s discovery adds to recent studies suggesting that K2-18 b could be a Hycean exoplanet, one which has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

The first insight into the atmospheric properties of this habitable-zone exoplanet came from observations with NASA’s Hubble Space Telescope, which prompted further studies that have since changed our understanding of the system.

K2-18 b orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light-years from Earth in the constellation Leo. Exoplanets such as K2-18 b, which have sizes between those of Earth and Neptune, are unlike anything in our solar system.

This lack of equivalent nearby planets means that these ‘sub-Neptunes’ are poorly understood, and the nature of their atmospheres is a matter of active debate among astronomers.

The suggestion that the sub-Neptune K2-18 b could be a Hycean exoplanet is intriguing, as some astronomers believe that these worlds are promising environments to search for evidence of life on exoplanets.

"Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere," explained Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper announcing these results. "Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations."

The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. These initial Webb observations also provided a possible detection of a molecule called dimethyl sulfide (DMS).

On Earth, DMS is only produced by life. The bulk of the DMS in Earth’s atmosphere is emitted from phytoplankton in marine environments.

The inference of DMS is less robust and requires further validation. “Upcoming Webb observations should be able to confirm if DMS is indeed present in the atmosphere of K2-18 b at significant levels,” explained Madhusudhan.

While K2-18 b lies in the habitable zone, and is now known to harbor carbon-bearing molecules, this does not necessarily mean that the planet can support life. The planet's large size — with a radius 2.6 times the radius of Earth — means that the planet’s interior likely contains a large mantle of high-pressure ice, like Neptune, but with a thinner hydrogen-rich atmosphere and an ocean surface.

Hycean worlds are predicted to have oceans of water. However, it is also possible that the ocean is too hot to be habitable or be liquid.

"Although this kind of planet does not exist in our solar system, sub-Neptunes are the most common type of planet known so far in the galaxy," explained team member Subhajit Sarkar of Cardiff University. “We have obtained the most detailed spectrum of a habitable-zone sub-Neptune to date, and this allowed us to work out the molecules that exist in its atmosphere.”

Characterizing the atmospheres of exoplanets like K2-18 b — meaning identifying their gases and physical conditions — is a very active area in astronomy. However, these planets are outshone — literally — by the glare of their much larger parent stars, which makes exploring exoplanet atmospheres particularly challenging.

The team sidestepped this challenge by analyzing light from K2-18 b's parent star as it passed through the exoplanet's atmosphere. K2-18 b is a transiting exoplanet, meaning that we can detect a drop in brightness as it passes across the face of its host star.

This is how the exoplanet was first discovered in 2015 with NASA’s K2 mission. This means that during transits a tiny fraction of starlight will pass through the exoplanet's atmosphere before reaching telescopes like Webb.

The starlight's passage through the exoplanet's atmosphere leaves traces that astronomers can piece together to determine the gases of the exoplanet's atmosphere.

"This result was only possible because of the extended wavelength range and unprecedented sensitivity of Webb, which enabled robust detection of spectral features with just two transits," said Madhusudhan. "For comparison, one transit observation with Webb provided comparable precision to eight observations with Hubble conducted over a few years and in a relatively narrow wavelength range."

"These results are the product of just two observations of K2-18 b, with many more on the way,” explained team member Savvas Constantinou of the University of Cambridge. “This means our work here is but an early demonstration of what Webb can observe in habitable-zone exoplanets.”

The team’s results were accepted for publication in The Astrophysical Journal Letters.

The team now intends to conduct follow-up research with the telescope's MIRI (Mid-Infrared Instrument) spectrograph that they hope will further validate their findings and provide new insights into the environmental conditions on K2-18 b.

"Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the universe," concluded Madhusudhan. "Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest."

Source: NASA.Gov

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NASA, CSA, ESA, R. Crawford (STScI), J. Olmsted (STScI), Science: N. Madhusudhan (Cambridge University)

Hubble's Successor Receives Accolades for Its On-Orbit Achievements in 2022...

Northrop Grumman

NASA’s Webb Telescope Awarded Robert H. Goddard Memorial Trophy (News Release)

The team behind NASA’s James Webb Space Telescope has been selected to receive the 2023 Robert H. Goddard Memorial Trophy, the premier award from the National Space Club and Foundation. This annual award honors an individual, group or program deemed by the Club to have made the most significant contribution to space activity in the previous year.

The award will be presented at the Club’s yearly Dr. Robert H. Goddard Memorial Dinner in Washington on March 10, 2023.

In 2022, the Webb team successfully completed an intricate series of deployments to unfold the observatory into its final configuration in space. They then precisely aligned its mirrors to within nanometers, set up and tested its powerful instruments, and officially began Webb’s mission to explore the infrared universe.

With its optics performing nearly twice as well as the mission required, Webb has already spotted some of the earliest galaxies ever observed, peered through dusty clouds to see stars forming, and provided a more detailed look at the atmospheres of planets outside our solar system than ever before. The Goddard Trophy will recognize the contributions of the team that designed, developed and now operate Webb, including individuals from NASA’s Goddard Space Flight Center, Greenbelt, Maryland; Northrop Grumman, Redondo Beach, California; the Space Telescope Science Institute, Baltimore; and Ball Aerospace, Boulder, Colorado.

The mission was also made possible by many international contributions from partnerships with ESA (European Space Agency) and CSA (Canadian Space Agency).

“Our team designed the James Webb Space Telescope to see the first lights that illuminated our universe,” said Mike Menzel, NASA Mission Systems Engineer for Webb at the Goddard Space Flight Center in Greenbelt, Maryland. “This required the largest ‘first of its kind’ telescope ever put into space along with 50 of the most complex deployments ever attempted to essentially re-build it on-orbit. After all these many years and many engineering challenges our team was struck with awe and wonder at the first images, and the satisfaction of knowing that whatever is out there we will see it.”

Recent winners of the Goddard Memorial Trophy include the teams behind NASA’s Ingenuity Mars Helicopter, New Horizons and Kepler mission.

Webb, an international mission led by NASA with its partners ESA (European Space Agency) and CSA (Canadian Space Agency), is the world’s premier space science observatory. Its design pushed the boundaries of space telescope capabilities to solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it.

NASA Headquarters, Washington oversees the Webb Telescope mission. NASA Goddard manages Webb for the agency and oversees work on the mission performed by the Space Telescope Science Institute, Northrop Grumman and other mission partners.

In addition to Goddard, several NASA centers contributed to the project, including the agency’s Johnson Space Center in Houston, Jet Propulsion Laboratory in Southern California, Marshall Space Flight Center in Huntsville, Alabama, Ames Research Center in California’s Silicon Valley, and others. Webb’s accomplishments have also recently been recognized by organizations including Aviation Week, Bloomberg Businessweek, Popular Science and TIME.

Source: NASA.Gov

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ESA / Webb, NASA & CSA, J. Lee and the PHANGS-JWST Team. Acknowledgement: J. Schmidt

Webb's Predecessor Spots Two Potential Ocean Worlds Located 218 Light-Years Away...

NASA, ESA, L. Hustak (STScI)

Hubble Helps Discover a New Type of Planet Largely Composed of Water (News Release - December 15)

Researchers have found evidence for the existence of a new type of planet they have called a “water world,” where water makes up a large fraction of the entire planet. These worlds, discovered in a planetary system 218 light-years away, are unlike any planets in our solar system.

The team, led by Caroline Piaulet of the Institute for Research on Exoplanets (iREx) at the University of Montreal, published a detailed study of a planetary system known as Kepler-138 in the journal Nature Astronomy on 15 December.

Piaulet, who is a member of Björn Benneke’s research team at the University of Montreal, observed the exoplanets Kepler-138 c and Kepler-138 d with both the NASA/ESA Hubble Space Telescope and NASA’s Spitzer Space Telescope. She found that the planets could be composed largely of water.

Water wasn’t directly detected, but by comparing the sizes and masses of the planets to models, they conclude that a significant fraction of their volume — up to half of it — should be made of materials that are lighter than rock but heavier than hydrogen or helium (which constitute the bulk of gas-giant planets like Jupiter). The most common candidate material is water.

“We previously thought that planets that were a bit larger than Earth were big balls of metal and rock, like scaled-up versions of Earth, and that’s why we called them super-Earths,” explained Benneke. "However, we have now shown that these two planets, Kepler-138 c and d, are quite different in nature and that a large fraction of their entire volume is likely composed of water. It is the best evidence yet for water worlds, a type of planet that was theorised by astronomers to exist for a long time.”

With volumes more than three times that of Earth and masses twice as big, planets c and d have much lower densities than Earth. This is surprising because most of the planets just slightly bigger than Earth that have been studied in detail so far all seemed to be rocky worlds like ours.

The closest comparison, say researchers, would be some of the icy moons in the outer solar system that are also largely composed of water surrounding a rocky core.

“Imagine larger versions of Europa or Enceladus, the water-rich moons orbiting Jupiter and Saturn, but brought much closer to their star,” explained Piaulet. “Instead of an icy surface, they would harbour large water-vapour envelopes."

“The secure identification of an object with the density of the icy moons of the solar system, but significantly larger and more massive, clearly demonstrates the great diversity of exoplanets,” added team member Jose-Manuel Almenara of Grenoble Alpes University in France. “This is expected to be the outcome of a variety of formation and evolution processes.”

Researchers caution that the planets may not have oceans like those on Earth directly at the planet’s surface. “The temperature in Kepler-138 d’s atmosphere is likely above the boiling point of water, and we expect a thick dense atmosphere made of steam on this planet. Only under that steam atmosphere could there potentially be liquid water at high pressure, or even water in another phase that occurs at high pressures, called a supercritical fluid," Piaulet said.

The NASA/ESA/CSA James Webb Space Telescope will also facilitate valuable follow-up research. “Now that we have securely identified the ‘water-world’ Kepler-138 d, the James Webb Space Telescope is the key to unveiling the atmospheric composition of such an exotic object,” shared team member Daria Kubyshkina of the Austrian Academy of Sciences. “It will give us critical information enabling us to compare the composition of the icy moons of the solar system with that of their larger and heavier extrasolar counterparts.

Recently, another team at the University of Montreal found a planet called TOI-1452b that could potentially be covered with a liquid-water ocean, but Webb will be needed to also confirm this.

In 2014 data from the NASA Kepler Space Telescope allowed astronomers to announce the detection of three planets orbiting Kepler-138, a red dwarf star in the constellation Lyra. This was based on a measurable dip in starlight as each planet momentarily passed in front of the star.

Benneke and his colleague Diana Dragomir, from the University of New Mexico, came up with the idea of re-observing the planetary system with the Hubble and Spitzer space telescopes between 2014 and 2016 to catch more transits of Kepler-138 d, the third planet in the system, in order to study its atmosphere.

The secure identification of an object with the density of the icy moons of the solar system, but significantly larger and more massive, clearly demonstrates the great diversity of exoplanets, which is expected to be the outcome of a variety of formation and evolution processes.

A New Exoplanet in the System

While the earlier Kepler space telescope observations only showed transits of three small planets around Kepler-138, Piaulet and her team were surprised to find that the Hubble and Spitzer observations required the presence of a fourth planet in the system, Kepler-138 e.

This newly-found planet is small and farther from its star than the three others, taking 38 days to complete an orbit. The planet is in the habitable zone of its star, a temperate region where it receives just the right amount of heat from its cool star to be neither too hot nor too cold to allow the presence of liquid water.

The nature of this additional, newly-found planet, however, remains an open question because it does not seem to transit its host star. Observing the exoplanet’s transit would have allowed astronomers to determine its size.

With Kepler-138 e now in the picture, the masses of the previously-known planets were measured again via the transit timing-variation method, which involves tracking small variations in the precise moments of the planets’ transits in front of their star caused by the gravitational pull of other nearby planets. The researchers had another surprise: they found that the two water worlds Kepler-138 c and d are “twin” planets, with virtually the same size and mass, while they were previously thought to be drastically different.

The closer-in planet, Kepler-138 b, on the other hand, is confirmed to be a small Mars-mass planet, one of the smallest exoplanets known to date.

“As our instruments and techniques become sensitive enough to find and study planets that are farther from their stars, we might start finding a lot more of these water worlds," Benneke concluded.

Source: European Space Agency

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Hubble helped find evidence of two exoplanets (planets that orbit stars beyond our Sun) where water makes up a large fraction of the entire planet.

Located 218 light-years away, these exoplanets are unlike any planets in our own solar system: https://t.co/4wlPFzmSlW pic.twitter.com/wWfO9VeWDh

— Hubble (@NASAHubble) December 15, 2022

The Tally of Alien Worlds in Our Galaxy Has Reached a New Record Today...

NASA / JPL - Caltech

Cosmic Milestone: NASA Confirms 5,000 Exoplanets (News Release)

The count of confirmed exoplanets just ticked past the 5,000 mark, representing a 30-year journey of discovery led by NASA space telescopes.

Not so long ago, we lived in a universe with only a small number of known planets, all of them orbiting our Sun. But a new raft of discoveries marks a scientific high point: More than 5,000 planets are now confirmed to exist beyond our solar system.

The planetary odometer turned on March 21, with the latest batch of 65 exoplanets – planets outside our immediate solar family – added to the NASA Exoplanet Archive. The archive records exoplanet discoveries that appear in peer-reviewed, scientific papers, and that have been confirmed using multiple detection methods or by analytical techniques.

The 5,000-plus planets found so far include small, rocky worlds like Earth, gas giants many times larger than Jupiter, and “hot Jupiters” in scorchingly close orbits around their stars. There are “super-Earths,” which are possible rocky worlds bigger than our own, and “mini-Neptunes,” smaller versions of our system’s Neptune. Add to the mix planets orbiting two stars at once and planets stubbornly orbiting the collapsed remnants of dead stars.

“It’s not just a number,” said Jessie Christiansen, science lead for the archive and a research scientist with the NASA Exoplanet Science Institute at Caltech in Pasadena. “Each one of them is a new world, a brand-new planet. I get excited about every one because we don’t know anything about them.”

We do know this: Our galaxy likely holds hundreds of billions of such planets. The steady drumbeat of discovery began in 1992 with strange new worlds orbiting an even stranger star. It was a type of neutron star known as a pulsar, a rapidly-spinning stellar corpse that pulses with millisecond bursts of searing radiation. Measuring slight changes in the timing of the pulses allowed scientists to reveal planets in orbit around the pulsar.

Finding just three planets around this spinning star essentially opened the floodgates, said Alexander Wolszczan, the lead author on the paper that, 30 years ago, unveiled the first planets to be confirmed outside our solar system.

“If you can find planets around a neutron star, planets have to be basically everywhere,” Wolszczan said. “The planet-production process has to be very robust.”

Wolszczan, who still searches for exoplanets as a professor at Penn State, says we’re opening an era of discovery that will go beyond simply adding new planets to the list. The Transiting Exoplanet Survey Satellite (TESS), launched in 2018, continues to make new exoplanet discoveries. But soon powerful next-generation telescopes and their highly-sensitive instruments, starting with the recently-launched James Webb Space Telescope, will capture light from the atmospheres of exoplanets, reading which gases are present to potentially identify tell-tale signs of habitable conditions.

The Nancy Grace Roman Space Telescope, expected to launch in 2027, will make new exoplanet discoveries using a variety of methods. The ESA (European Space Agency) mission ARIEL, launching in 2029, will observe exoplanet atmospheres; a piece of NASA technology aboard, called CASE, will help zero in on exoplanet clouds and hazes.

“To my thinking, it is inevitable that we’ll find some kind of life somewhere – most likely of some primitive kind,” Wolszczan said. The close connection between the chemistry of life on Earth and chemistry found throughout the universe, as well as the detection of widespread organic molecules, suggests detection of life itself is only a matter of time, he added.

How to Find Other Worlds

The picture didn’t always look so bright. The first planet detected around a Sun-like star, in 1995, turned out to be a hot Jupiter: a gas giant about half the mass of our own Jupiter in an extremely close, four-day orbit around its star. A year on this planet, in other words, lasts only four days.

More such planets appeared in the data from ground-based telescopes once astronomers learned to recognize them – first dozens, then hundreds. They were found using the “wobble” method: tracking slight back-and-forth motions of a star, caused by gravitational tugs from orbiting planets. But still, nothing looked likely to be habitable.

Finding small, rocky worlds more like our own required the next big leap in exoplanet-hunting technology: the “transit” method. Astronomer William Borucki came up with the idea of attaching extremely sensitive light detectors to a telescope, then launching it into space. The telescope would stare for years at a field of more than 170,000 stars, searching for tiny dips in starlight when a planet crossed a star’s face.

That idea was realized in the Kepler Space Telescope.

Borucki, principal investigator of the now-retired Kepler mission, says its launch in 2009 opened a new window on the universe.

“I get a real feeling of satisfaction, and really of awe at what’s out there,” he said. “None of us expected this enormous variety of planetary systems and stars. It’s just amazing.”

Source: Jet Propulsion Laboratory

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Photo of the Day: The Delta 2 Is Now Immortalized at the Rocket Garden in Florida...

United Launch Alliance

Just thought I'd share this image of the Delta 2 rocket that is now on display in the 'Rocket Garden' at the Kennedy Space Center Visitor Complex in Florida! This retired launch vehicle was officially unveiled to the public two days ago...and now joins space shuttle Atlantis on my list of historic vehicles that I want to see when I make another trip to NASA's Kennedy Space Center (KSC) in Florida.

I was planning to re-visit KSC this year to see the Space Launch System (SLS) stand tall at Launch Complex 39B, but 1.) The COVID-19 pandemic gave me second thoughts about flying to Florida—a Republican-run coronavirus hotspot—this year (even when I hopefully get vaccinated next month), 2.) The first launch of SLS on Artemis 1 will most likely be postponed to early 2022 after it took two attempts to conduct a successful Green Run hot fire test at Stennis Space Center in Mississippi, and 3.) I just put the finishing touches on paying off a major credit card debt using my $1,400 stimulus payment last week. (Thank you, President Biden!) But I might change my mind.

So why am I fond of the Delta 2, you ask? It was responsible for launching Mars Pathfinder, the Phoenix Mars lander, the Kepler telescope and the Dawn spacecraft to the cosmos over the past 25 years. Click on this page to know why these missions—among many, many more—mean so much to me! Happy Thursday.

A good old fashioned Rocket Raising. #DeltaII assembled at @ExploreSpaceKSC. This actual rocket, with replica solid rocket boosters, stands 13 stories tall & now serves as a tribute to its foundational & reliable service to the U.S. space program. #ThankYouDeltaII #ToryTimelapse pic.twitter.com/qNWjPTdOtD

— Tory Bruno (@torybruno) March 23, 2021

An Exoplanet Discovery Made by the Kepler Space Telescope Has Been Confirmed by TESS...

Caltech / R. Hurt (IPAC)

Discovery Alert: A Forgotten Planet Found in a Triple-Star System (News Release - January 12)

Shortly after NASA's Kepler mission began operations back in 2009, the space telescope spotted what was thought to be a planet about half the size of Saturn in a multiple-star system. KOI-5Ab was only the second planet candidate to be found by the mission, and exciting as it was at the time, it was ultimately set aside as Kepler racked up more and more planet discoveries.

By the end of the spacecraft’s operations in 2018, Kepler had discovered a whopping 2,394 exoplanets, or planets orbiting stars beyond our sun, and an additional 2,366 exoplanet candidates that would still need confirmation.

“KOI-5Ab got abandoned because it was complicated, and we had thousands of candidates,” said David Ciardi, chief scientist of NASA's Exoplanet Science Institute. “There were easier pickings than KOI-5Ab, and we were learning something new from Kepler every day, so that KOI-5 was mostly forgotten.”

Now, after a lengthy hunt that spanned many years and many telescopes, Ciardi said he has "resurrected KOI-5Ab from the dead." Thanks to new observations from NASA’s second planet-hunting mission, the Transiting Exoplanet Survey Satellite, or TESS, and a number of ground-based telescopes, Ciardi was finally able to untangle all the evidence surrounding KOI-5Ab and prove its existence. There are some intriguing details about it to mull over.

Most likely a gas giant planet like Jupiter or Saturn in our solar system given its size, KOI-5Ab is unusual in that it orbits a star in a system with two other companion stars, circling on a plane that’s out of alignment with at least one of the stars. The arrangement calls into question how each member in this system formed out of the same swirling clouds of gas and dust. Ciardi, who is located at Caltech in Pasadena, California presented the findings at a virtual meeting of the American Astronomical Society.

Picking up the trail

After its initial detection by Kepler, Ciardi and other researchers picked up the trail on KOI-5Ab as part of a cache of planet candidates they were following up on. Using data from the W. M. Keck Observatory in Hawaii, Caltech's Palomar Observatory near San Diego, and Gemini North in Hawaii, Ciardi and other astronomers determined that KOI-5b appeared to be circling one star in a triple-star system. However, they still couldn’t tease out whether the planet signal was actually an erroneous glitch from one of the two other stars, or, if the planet was real, which of the stars it orbited.

Then, in 2018, TESS came along. Like Kepler, TESS looks for the blinking of starlight that comes when a planet crosses in front of, or transits, a star. TESS observed a portion of Kepler's field of view, including the KOI-5 system. Sure enough, TESS also identified KOI-5Ab as a candidate planet, though TESS calls it TOI-1241b. As Kepler had observed previously, TESS found that the planet orbited its star roughly every five days.

"I thought to myself, 'I remember this target,'" said Ciardi, after seeing the TESS data. “But we still couldn’t determine definitively if the planet was real or if the blip in the data came from another star in the system – it could have been a fourth star.”

Clues in the wobbles

He then went back and re-analyzed all the data, and then searched for new clues from ground-based telescopes. Deploying an alternate technique to Kepler and TESS, the Keck Observatory is often used for follow-up searches of exoplanets by measuring the slight wobble in a star as a planet circles around it and exerts a gravitational tug. Ciardi, teaming up with other scientists through an exoplanet collaboration group called the California Planet Search, looked for any wobbles in Keck’s data on the KOI-5 system. They were able to tease out a wobble produced by the inner companion star orbiting the primary star from the wobble of the apparent planet as it orbits the primary star. Together, the different collections of data from the space- and ground-based telescopes helped confirm that KOI-5Ab is, indeed, a planet orbiting the primary star.

“Bingo – it was there! If it weren't for TESS looking at the planet again, I would never have gone back and done all this detective work," he said. “But it truly did take a lot of sleuthing within data collected from many different telescopes to finally nail down this planet.”

KOI-5Ab orbits Star A, which has a relatively close companion, Star B. Star A and Star B orbit each other every 30 years. A third gravitationally bound star, Star C, orbits stars A and B every 400 years.

A skewed orbit

The combined data set also reveals that the orbital plane of the planet is not aligned with the orbital plane of Star B, the second inner star as might be expected if the stars and planet all formed from the same disk of swirling material. Astronomers are not sure what caused the misalignment of KOI-5Ab but believe that the second star gravitationally kicked the planet during its development, skewing its orbit and causing it to migrate inward. Triple-star systems make up about 10% of all star systems.

This is not the first evidence of planets in double- and triple-star systems. One striking case involves the triple-star system GW Orionis, in which a planet-forming disk has been torn into distinct, misaligned rings, where planets may be forming. Yet despite hundreds of discoveries of planets in multiple-star system, far fewer planets have been observed than in single-star systems. This could be due to an observational bias (single-star planets are easier to detect), or because planet formation is in fact less common in multiple-star systems.

“This research emphasizes the importance of NASA’s full fleet of space telescopes and their synergy with ground-based systems," said Jessie Dotson, the project scientist for the Kepler space telescope at NASA’s Ames Research Center in California’s Silicon Valley. "Discoveries like this one can be a long haul.”

New and future instruments, such as the Palomar Radial Velocity Instrument at the 200-inch Hale Telescope at Palomar, the NASA and National Science Foundation’s NEID instrument in southern Arizona, and the Keck Planet Finder will open up new avenues for learning about exoplanets.

Source: NASA.Gov

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Caltech / R. Hurt (IPAC)

Kepler Update: The Exoplanet Hunter Is Still Making Discoveries Almost 2 Years After It Fell Silent in Space...

NASA / Ames Research Center / Daniel Rutter

Earth-Size, Habitable Zone Planet Found Hidden in Early NASA Kepler Data (News Release - April 15)

A team of transatlantic scientists, using reanalyzed data from NASA’s Kepler space telescope, has discovered an Earth-size exoplanet orbiting in its star's habitable zone, the area around a star where a rocky planet could support liquid water.

Scientists discovered this planet, called Kepler-1649c, when looking through old observations from Kepler, which the agency retired in 2018. While previous searches with a computer algorithm misidentified it, researchers reviewing Kepler data took a second look at the signature and recognized it as a planet. Out of all the exoplanets found by Kepler, this distant world – located 300 light-years from Earth – is most similar to Earth in size and estimated temperature.

This newly revealed world is only 1.06 times larger than our own planet. Also, the amount of starlight it receives from its host star is 75% of the amount of light Earth receives from our Sun – meaning the exoplanet's temperature may be similar to our planet’s, as well. But unlike Earth, it orbits a red dwarf. Though none have been observed in this system, this type of star is known for stellar flare-ups that may make a planet's environment challenging for any potential life.

"This intriguing, distant world gives us even greater hope that a second Earth lies among the stars, waiting to be found,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington. “The data gathered by missions like Kepler and our Transiting Exoplanet Survey Satellite (TESS) will continue to yield amazing discoveries as the science community refines its abilities to look for promising planets year after year."

There is still much that is unknown about Kepler-1649c, including its atmosphere, which could affect the planet's temperature. Current calculations of the planet's size have significant margins of error, as do all values in astronomy when studying objects so far away. But based on what is known, Kepler-1649c is especially intriguing for scientists looking for worlds with potentially habitable conditions.

There are other exoplanets estimated to be closer to Earth in size, such as TRAPPIST-1f and, by some calculations, Teegarden c. Others may be closer to Earth in temperature, such as TRAPPIST-1d and TOI 700d. But there is no other exoplanet that is considered to be closer to Earth in both of these values that also lies in the habitable zone of its system.

"Out of all the mislabeled planets we've recovered, this one's particularly exciting – not just because it's in the habitable zone and Earth-size, but because of how it might interact with this neighboring planet," said Andrew Vanderburg, a researcher at the University of Texas at Austin and first author on the paper released today in The Astrophysical Journal Letters. "If we hadn't looked over the algorithm's work by hand, we would have missed it."

Kepler-1649c orbits its small red dwarf star so closely that a year on Kepler-1649c is equivalent to only 19.5 Earth days. The system has another rocky planet of about the same size, but it orbits the star at about half the distance of Kepler-1649c, similar to how Venus orbits our Sun at about half the distance that Earth does. Red dwarf stars are among the most common in the galaxy, meaning planets like this one could be more common that we previously thought.

Looking for False Positives

Previously, scientists on the Kepler mission developed an algorithm called Robovetter to help sort through the massive amounts of data produced by the Kepler spacecraft, managed by NASA's Ames Research Center in California's Silicon Valley. Kepler searched for planets using the transit method, staring at stars, looking for dips in brightness as planets passed in front of their host stars.

Most of the time, those dips come from phenomena other than planets – ranging from natural changes in a star's brightness to other cosmic objects passing by – making it look like a planet is there when it's not. Robovetter's job was to distinguish the 12% of dips that were real planets from the rest. Those signatures Robovetter determined to be from other sources were labeled "false positives," the term for a test result mistakenly classified as positive.

With an enormous number of tricky signals, astronomers knew the algorithm would make mistakes and would need to be double-checked – a perfect job for the Kepler False Positive Working Group. That team reviews Robovetter's work, going through each false positive to ensure they are truly errors and not exoplanets, ensuring fewer potential discoveries are overlooked. As it turns out, Robovetter had mislabeled Kepler-1649c.

Even as scientists work to further automate analysis processes to get the most science as possible out of any given dataset, this discovery shows the value of double-checking automated work. Even six years after Kepler stopped collecting data from the original Kepler field – a patch of sky it stared at from 2009 to 2013, before going on to study many more regions – this rigorous analysis uncovered one of the most unique Earth-analogs discovered yet.

A Possible Third Planet

Kepler-1649c not only is one of the best matches to Earth in terms of size and energy received from its star, but it provides an entirely new look at its home system. For every nine times the outer planet in the system orbits the host star, the inner planet orbits almost exactly four times. The fact that their orbits match up in such a stable ratio indicates the system itself is extremely stable, and likely to survive for a long time.

Nearly perfect period ratios are often caused by a phenomenon called orbital resonance, but a nine-to-four ratio is relatively unique among planetary systems. Usually resonances take the form of ratios such as two-to-one or three-to-two. Though unconfirmed, the rarity of this ratio could hint to the presence of a middle planet with which both the inner and outer planets revolve in synchronicity, creating a pair of three-to-two resonances.

The team looked for evidence of such a mystery third planet, with no results. However, that could be because the planet is too small to see or at an orbital tilt that makes it impossible to find using Kepler's transit method.

Either way, this system provides yet another example of an Earth-size planet in the habitable zone of a red dwarf star. These small and dim stars require planets to orbit extremely close to be within that zone – not too warm and not too cold – for life as we know it to potentially exist. Though this single example is only one among many, there is increasing evidence that such planets are common around red dwarfs.

"The more data we get, the more signs we see pointing to the notion that potentially habitable and Earth-size exoplanets are common around these kinds of stars," said Vanderburg. "With red dwarfs almost everywhere around our galaxy, and these small, potentially habitable and rocky planets around them, the chance one of them isn't too different than our Earth looks a bit brighter."

Source: NASA.Gov

TESS Update #2: Kepler's Successor Finds Its First Potentially-Habitable Exoplanet...

NASA's Goddard Space Flight Center / Chris Smith

NASA Planet Hunter Finds its 1st Earth-size Habitable-zone World (News Release - January 6)

NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star’s habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface. Scientists confirmed the find, called TOI 700 d, using NASA’s Spitzer Space Telescope and have modeled the planet’s potential environments to help inform future observations.

TOI 700 d is one of only a few Earth-size planets discovered in a star's habitable zone so far. Others include several planets in the TRAPPIST-1 system and other worlds discovered by NASA’s Kepler Space Telescope.

“TESS was designed and launched specifically to find Earth-sized planets orbiting nearby stars,” said Paul Hertz, astrophysics division director at NASA Headquarters in Washington. “Planets around nearby stars are easiest to follow-up with larger telescopes in space and on Earth. Discovering TOI 700 d is a key science finding for TESS. Confirming the planet’s size and habitable zone status with Spitzer is another win for Spitzer as it approaches the end of science operations this January."

TESS monitors large swaths of the sky, called sectors, for 27 days at a time. This long stare allows the satellite to track changes in stellar brightness caused by an orbiting planet crossing in front of its star from our perspective, an event called a transit.

TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It’s roughly 40% of the Sun’s mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission’s first year, and scientists caught multiple transits by its three planets.

The star was originally misclassified in the TESS database as being more similar to our Sun, which meant the planets appeared larger and hotter than they really are. Several researchers, including Alton Spencer, a high school student working with members of the TESS team, identified the error.

“When we corrected the star’s parameters, the sizes of its planets dropped, and we realized the outermost one was about the size of Earth and in the habitable zone,” said Emily Gilbert, a graduate student at the University of Chicago. “Additionally, in 11 months of data we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions.”

Gilbert and other researchers presented the findings at the 235th meeting of the American Astronomical Society in Honolulu, and three papers — one of which Gilbert led — have been submitted to scientific journals.

The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth — between the sizes of Earth and Neptune — orbits every 16 days and is likely a gas-dominated world. TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20% larger than Earth, orbits every 37 days and receives from its star 86% of the energy that the Sun provides to Earth. All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed in daylight.

A team of scientists led by Joseph Rodriguez, an astronomer at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts, requested follow-up observations with Spitzer to confirm TOI 700 d.

“Given the impact of this discovery — that it is TESS’s first habitable-zone Earth-size planet — we really wanted our understanding of this system to be as concrete as possible,” Rodriguez said. “Spitzer saw TOI 700 d transit exactly when we expected it to. It’s a great addition to the legacy of a mission that helped confirm two of the TRAPPIST-1 planets and identify five more.”

The Spitzer data increased scientists’ confidence that TOI 700 d is a real planet and sharpened their measurements of its orbital period by 56% and its size by 38%. It also ruled out other possible astrophysical causes of the transit signal, such as the presence of a smaller, dimmer companion star in the system.

Rodriguez and his colleagues also used follow-up observations from a 1-meter ground-based telescope in the global Las Cumbres Observatory network to improve scientists’ confidence in the orbital period and size of TOI 700 c by 30% and 36%, respectively.

Because TOI 700 is bright, nearby, and shows no sign of stellar flares, the system is a prime candidate for precise mass measurements by current ground-based observatories. These measurements could confirm scientists’ estimates that the inner and outer planets are rocky and the middle planet is made of gas.

Future missions may be able to identify whether the planets have atmospheres and, if so, even determine their compositions.

While the exact conditions on TOI 700 d are unknown, scientists can use current information, like the planet’s size and the type of star it orbits, to generate computer models and make predictions. Researchers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, modeled 20 potential environments of TOI 700 d to gauge if any version would result in surface temperatures and pressures suitable for habitability.

Their 3D climate models examined a variety of surface types and atmospheric compositions typically associated with what scientists regard to be potentially habitable worlds. Because TOI 700 d is tidally locked to its star, the planet’s cloud formations and wind patterns may be strikingly different from Earth’s.

One simulation included an ocean-covered TOI 700 d with a dense, carbon-dioxide-dominated atmosphere similar to what scientists suspect surrounded Mars when it was young. The model atmosphere contains a deep layer of clouds on the star-facing side. Another model depicts TOI 700 d as a cloudless, all-land version of modern Earth, where winds flow away from the night side of the planet and converge on the point directly facing the star.

When starlight passes through a planet’s atmosphere, it interacts with molecules like carbon dioxide and nitrogen to produce distinct signals, called spectral lines. The modeling team, led by Gabrielle Engelmann-Suissa, a Universities Space Research Association visiting research assistant at Goddard, produced simulated spectra for the 20 modeled versions of TOI 700 d.

“Someday, when we have real spectra from TOI 700 d, we can backtrack, match them to the closest simulated spectrum, and then match that to a model,” Engelmann-Suissa said. “It’s exciting because no matter what we find out about the planet, it’s going to look completely different from what we have here on Earth.”

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT’s Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.

The Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Space operations are based at Lockheed Martin Space in Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.

The modeling work was funded through the Sellers Exoplanet Environments Collaboration at Goddard, a multidisciplinary collaboration that brings together experts to build comprehensive and sophisticated computer models to better analyze current and future exoplanet observations.

Source: NASA.Gov

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TESS Update: 2020 Begins with an Amazing Discovery Made by Kepler's Successor...

NASA's Goddard Space Flight Center / Chris Smith

NASA’s TESS Mission Uncovers Its 1st World With Two Stars (News Release)

In 2019, when Wolf Cukier finished his junior year at Scarsdale High School in New York, he joined NASA’s Goddard Space Flight Center in Greenbelt, Maryland, as a summer intern. His job was to examine variations in star brightness captured by NASA’s Transiting Exoplanet Survey Satellite (TESS) and uploaded to the Planet Hunters TESS citizen science project.

“I was looking through the data for everything the volunteers had flagged as an eclipsing binary, a system where two stars circle around each other and from our view eclipse each other every orbit,” Cukier said. “About three days into my internship, I saw a signal from a system called TOI 1338. At first I thought it was a stellar eclipse, but the timing was wrong. It turned out to be a planet.”

TOI 1338 b, as it is now called, is TESS’s first circumbinary planet, a world orbiting two stars. The discovery was featured in a panel discussion on Monday, Jan. 6, at the 235th American Astronomical Society meeting in Honolulu. A paper, which Cukier co-authored along with scientists from Goddard, San Diego State University, the University of Chicago and other institutions, has been submitted to a scientific journal.

The TOI 1338 system lies 1,300 light-years away in the constellation Pictor. The two stars orbit each other every 15 days. One is about 10% more massive than our Sun, while the other is cooler, dimmer and only one-third the Sun’s mass.

TOI 1338 b is the only known planet in the system. It’s around 6.9 times larger than Earth, or between the sizes of Neptune and Saturn. The planet orbits in almost exactly the same plane as the stars, so it experiences regular stellar eclipses.

TESS has four cameras, which each take a full-frame image of a patch of the sky every 30 minutes for 27 days. Scientists use the observations to generate graphs of how the brightness of stars change over time. When a planet crosses in front of its star from our perspective, an event called a transit, its passage causes a distinct dip in the star’s brightness.

But planets orbiting two stars are more difficult to detect than those orbiting one. TOI 1338 b’s transits are irregular, between every 93 and 95 days, and vary in depth and duration thanks to the orbital motion of its stars. TESS only sees the transits crossing the larger star; the transits of the smaller star are too faint to detect.

“These are the types of signals that algorithms really struggle with,” said lead author Veselin Kostov, a research scientist at the SETI Institute and Goddard. “The human eye is extremely good at finding patterns in data, especially non-periodic patterns like those we see in transits from these systems.”

This explains why Cukier had to visually examine each potential transit. For example, he initially thought TOI 1338 b’s transit was a result of the smaller star in the system passing in front of the larger one — both cause similar dips in brightness. But the timing was wrong for an eclipse.

After identifying TOI 1338 b, the research team used a software package called eleanor, named after Eleanor Arroway, the central character in Carl Sagan’s novel “Contact,” to confirm the transits were real and not a result of instrumental artifacts.

“Throughout all of its images, TESS is monitoring millions of stars,” said co-author Adina Feinstein, a graduate student at the University of Chicago. “That’s why our team created eleanor. It’s an accessible way to download, analyze and visualize transit data. We designed it with planets in mind, but other members of the community use it to study stars, asteroids and even galaxies.”

TOI 1338 had already been studied from the ground by radial velocity surveys, which measure motion along our line of sight. Kostov’s team used this archival data to analyze the system and confirm the planet. Its orbit is stable for at least the next 10 million years. The orbit’s angle to us, however, changes enough that the planet transit will cease after November 2023 and resume eight years later.

NASA’s Kepler and K2 missions previously discovered 12 circumbinary planets in 10 systems, all similar to TOI 1338 b. Observations of binary systems are biased toward finding larger planets, Kostov said. Transits of smaller bodies don’t have as big an effect on the stars’ brightness. TESS is expected to observe hundreds of thousands of eclipsing binaries during its initial two-year mission, so many more of these circumbinary planets should be waiting for discovery.

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT’s Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.

Source: NASA.Gov

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TESS Update: A New Exoplanet Has Been Found by Kepler's Successor...

NASA's Goddard Space Flight Center

NASA’s TESS Discovers its First Earth-size Planet (News Release)

NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size world. The planet, HD 21749c, is about 89% Earth’s diameter. It orbits HD 21749, a K-type star with about 70% of the Sun’s mass located 53 light-years away in the southern constellation Reticulum, and is the second planet TESS has identified in the system. The new world is likely rocky and circles very close to its star, completing one orbit in just under eight days. The planet is likely very hot, with surface temperatures perhaps as high as 800 degrees F (427 degrees C).

This is the 10th confirmed planet discovered by TESS, and hundreds of additional candidates are now being studied.

Scientists at the Massachusetts Institute of Technology and the Carnegie Institution for Science analyzed TESS transit data from the first four sectors of TESS observations to detect 11 periodic dips in the star’s brightness. From this, they determined that the star’s light was being partially blocked by a planet about the size of Earth.

The star that HD 21749c orbits is bright and relatively nearby, and therefore well suited to more detailed follow-up studies, which could provide critical information about the planet’s properties, including potentially the first mass measurement of an Earth-size planet found by TESS.

Source: NASA.Gov

Kepler's Final Exoplanet Discovery Was Actually Made a Decade Ago...

Gabriel Perez Diaz / Instituto de Astrofísica de Canarias

Discovery Alert! Kepler's First Planet Candidate Confirmed, 10 Years Later (News Release - March 5)

Despite being the very first planet candidate discovered by NASA’s Kepler space telescope, Kepler-1658b had a rocky road to confirmation. The initial estimate of the planet’s host star was off, so the sizes of both the star and Kepler-1658b were vastly underestimated. It was later marked as a false positive — that is, scientists thought the data did not really point to a planet — when the numbers didn’t quite add up for the effects seen on its star for a body of that size. Kepler-1658b moved from planet candidate to false positive and back until new software was used to refine the data and reclassify it, changing it from a data anomaly to possible planet.

Fortuitously, a team at the University of Hawaii was poised to step in at just the right time. As part of her first year research project, lead author Ashley Chontos, a graduate student with the university’s Institute for Astronomy, went back through Kepler data looking for targets to reanalyze in 2017.

“Our new analysis, which uses stellar sound waves observed in the Kepler data to characterize the star, demonstrated that the star is in fact three times larger than previously thought. This in turn means that the planet is three times larger, revealing that Kepler-1658b is actually a hot Jupiter,” Chontos said. With this refined analysis, everything pointed to it being a real planet. Next came confirmation.

“We alerted Dave Latham (a senior astronomer at the Smithsonian Astrophysical Observatory, and co-author on the paper) and his team collected the necessary spectroscopic data to unambiguously show that Kepler-1658b is a planet,” said Dan Huber, co-author and astronomer at the University of Hawaii. “As one of the pioneers of exoplanet science and a key figure behind the Kepler mission, it was particularly fitting to have Dave be part of this confirmation.”

Source: NASA.Gov

Photo of the Day: Kepler's Final Glimpse of the Cosmos...

NASA / Ames Research Center

Kepler’s Final Image Shows A Galaxy Full Of Possibilities (News Release)

NASA’s Kepler space telescope may be retired, but the discoveries continue to rack up for this historic planet-hunting mission. Kepler rang in the new year with several new planet discoveries, including a previously overlooked planet of an unusual size, as well as a super Earth and a Saturn-sized world orbiting a Sun-like star.

In the meantime, the Kepler mission has released its final record of the spacecraft’s full field of view before the depletion of fuel permanently ended its work. NASA retired the spacecraft on Oct. 30, 2018, to a safe orbit.

The “last light” image taken on Sept. 25 represents the final page of the final chapter of Kepler’s remarkable journey of data collection. It bookends the moment of intense excitement nine and a half years earlier when the spacecraft first opened its eye to the skies and captured its “first light” image. Kepler went on to discover more than 2,600 worlds beyond our solar system and statistically proved that our galaxy has even more planets than stars.

The blackened gaps in the center and along the top of the image are the result of earlier random part failures in the camera. Due to the modular design, the losses did not impact the rest of the instrument.

For this final field of view, Kepler’s last observation campaign in its extended mission, the telescope was pointed in the direction of the constellation Aquarius. It caught a glimpse of the renowned TRAPPIST-1 system with its seven rocky planets, at least three of them believed to be temperate worlds. Another target was the GJ 9827 system, a nearby bright star that hosts a planet that is considered an excellent opportunity for follow up observations with other telescopes to study an atmosphere of a faraway world.

Fortuitously, Kepler’s field of view also slightly overlapped with NASA’s new planet-hunter, the Transiting Exoplanet Survey Satellite, or TESS, affording astronomers the chance to compare and improve their understanding of the data received from the two spacecraft. Although Kepler’s transmitters have been turned off and it is no longer collecting science, its data will be mined for many years to come.

NASA's Ames Research Center in California’s Silicon Valley manages the Kepler and K2 missions for NASA’s Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation operated the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

Source: NASA.Gov

Kepler Update: Exoplanets Continue to be Discovered by the Space Telescope Even After It Has Fallen Silent...

NASA's Goddard Space Flight Center / Francis Reddy

Citizen Scientists Find New World with NASA Telescope (News Release)

Using data from NASA's Kepler space telescope, citizen scientists have discovered a planet roughly twice the size of Earth located within its star's habitable zone, the range of orbital distances where liquid water may exist on the planet's surface. The new world, known as K2-288Bb, could be rocky or could be a gas-rich planet similar to Neptune. Its size is rare among exoplanets - planets beyond our solar system.

"It's a very exciting discovery due to how it was found, its temperate orbit and because planets of this size seem to be relatively uncommon," said Adina Feinstein, a University of Chicago graduate student who discussed the discovery on Monday, Jan. 7, at the 233rd meeting of the American Astronomical Society in Seattle. She is also the lead author of a paper describing the new planet accepted for publication by The Astronomical Journal.

Located 226 light-years away in the constellation Taurus, the planet lies in a stellar system known as K2-288, which contains a pair of dim, cool M-type stars separated by about 5.1 billion miles (8.2 billion kilometers) - roughly six times the distance between Saturn and the Sun. The brighter star is about half as massive and large as the Sun, while its companion is about one-third the Sun's mass and size. The new planet, K2-288Bb, orbits the smaller, dimmer star every 31.3 days.

In 2017, Feinstein and Makennah Bristow, an undergraduate student at the University of North Carolina Asheville, worked as interns with Joshua Schlieder, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. They searched Kepler data for evidence of transits, the regular dimming of a star when an orbiting planet moves across the star's face.

Examining data from the fourth observing campaign of Kepler's K2 mission, the team noticed two likely planetary transits in the system. But scientists require a third transit before claiming the discovery of a candidate planet, and there wasn't a third signal in the observations they reviewed.

As it turned out, though, the team wasn't actually analyzing all of the data.

In Kepler's K2 mode, which ran from 2014 to 2018, the spacecraft repositioned itself to point at a new patch of sky at the start of each three-month observing campaign. Astronomers were initially concerned that this repositioning would cause systematic errors in measurements.

"Re-orienting Kepler relative to the Sun caused miniscule changes in the shape of the telescope and the temperature of the electronics, which inevitably affected Kepler's sensitive measurements in the first days of each campaign," said co-author Geert Barentsen, an astrophysicist at NASA's Ames Research Center in California's Silicon Valley and the director of the guest observer office for the Kepler and K2 missions.

To deal with this, early versions of the software that was used to prepare the data for planet-finding analysis simply ignored the first few days of observations - and that's where the third transit was hiding.

As scientists learned how to correct for these systematic errors, this trimming step was eliminated - but the early K2 data Barstow studied had been clipped.

"We eventually re-ran all data from the early campaigns through the modified software and then re-ran the planet search to get a list of candidates, but these candidates were never fully visually inspected," explained Schlieder, a co-author of the paper. "Inspecting, or vetting, transits with the human eye is crucial because noise and other astrophysical events can mimic transits."

Instead, the re-processed data were posted directly to Exoplanet Explorers, a project where the public searches Kepler's K2 observations to locate new transiting planets. In May 2017, volunteers noticed the third transit and began an excited discussion about what was then thought to be an Earth-sized candidate in the system, which caught the attention of Feinstein and her colleagues.

"That's how we missed it - and it took the keen eyes of citizen scientists to make this extremely valuable find and point us to it," Feinstein said.

The team began follow-up observations using NASA's Spitzer Space Telescope, the Keck II telescope at the W. M. Keck Observatory and NASA's Infrared Telescope Facility (the latter two in Hawaii), and also examined data from ESA's (the European Space Agency's) Gaia mission.

Estimated to be about 1.9 times Earth's size, K2-288Bb is half the size of Neptune. This places the planet within a recently discovered category called the Fulton gap, or radius gap. Among planets that orbit close to their stars, there's a curious dearth of worlds between about 1.5 and two times Earth's size. This is likely the result of intense starlight breaking up atmospheric molecules and eroding away the atmospheres of some planets over time, leaving behind two populations. Since K2-288Bb's radius places it in this gap, it may provide a case study of planetary evolution within this size range.

On Oct. 30, 2018, Kepler ran out of fuel and ended its mission after nine years, during which it discovered 2,600 confirmed planets around other stars - the bulk of those now known - along with thousands of additional candidates astronomers are working to confirm. And while NASA's Transiting Exoplanet Survey Satellite is the newest space-based planet hunter, this new finding shows that more discoveries await scientists in Kepler data.

Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation operated the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

Source: Jet Propulsion Laboratory

Farewell, Kepler, and We Thank You...

NASA / Wendy Stenzel / Daniel Rutter

NASA Retires Kepler Space Telescope, Passes Planet-Hunting Torch (Press Release)

After nine years in deep space collecting data that indicate our sky to be filled with billions of hidden planets – more planets even than stars – NASA’s Kepler space telescope has run out of fuel needed for further science operations. NASA has decided to retire the spacecraft within its current, safe orbit, away from Earth. Kepler leaves a legacy of more than 2,600 planet discoveries from outside our solar system, many of which could be promising places for life.

"As NASA's first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond," said Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington. "Not only did it show us how many planets could be out there, it sparked an entirely new and robust field of research that has taken the science community by storm. Its discoveries have shed a new light on our place in the universe, and illuminated the tantalizing mysteries and possibilities among the stars.”

Kepler has opened our eyes to the diversity of planets that exist in our galaxy. The most recent analysis of Kepler’s discoveries concludes that 20 to 50 percent of the stars visible in the night sky are likely to have small, possibly rocky, planets similar in size to Earth, and located within the habitable zone of their parent stars. That means they’re located at distances from their parent stars where liquid water – a vital ingredient to life as we know it – might pool on the planet surface.

The most common size of planet Kepler found doesn’t exist in our solar system – a world between the size of Earth and Neptune – and we have much to learn about these planets. Kepler also found nature often produces jam-packed planetary systems, in some cases with so many planets orbiting close to their parent stars that our own inner solar system looks sparse by comparison.

"When we started conceiving this mission 35 years ago we didn't know of a single planet outside our solar system," said the Kepler mission's founding principal investigator, William Borucki, now retired from NASA’s Ames Research Center in California’s Silicon Valley. "Now that we know planets are everywhere, Kepler has set us on a new course that's full of promise for future generations to explore our galaxy."

Launched on March 6, 2009, the Kepler space telescope combined cutting-edge techniques in measuring stellar brightness with the largest digital camera outfitted for outer space observations at that time. Originally positioned to stare continuously at 150,000 stars in one star-studded patch of the sky in the constellation Cygnus, Kepler took the first survey of planets in our galaxy and became the agency's first mission to detect Earth-size planets in the habitable zones of their stars.

"The Kepler mission was based on a very innovative design. It was an extremely clever approach to doing this kind of science," said Leslie Livesay, director for astronomy and physics at NASA’s Jet Propulsion Laboratory, who served as Kepler project manager during mission development. "There were definitely challenges, but Kepler had an extremely talented team of scientists and engineers who overcame them.”

Four years into the mission, after the primary mission objectives had been met, mechanical failures temporarily halted observations. The mission team was able to devise a fix, switching the spacecraft’s field of view roughly every three months. This enabled an extended mission for the spacecraft, dubbed K2, which lasted as long as the first mission and bumped Kepler's count of surveyed stars up to more than 500,000.

The observation of so many stars has allowed scientists to better understand stellar behaviors and properties, which is critical information in studying the planets that orbit them. New research into stars with Kepler data also is furthering other areas of astronomy, such as the history of our Milky Way galaxy and the beginning stages of exploding stars called supernovae that are used to study how fast the universe is expanding. The data from the extended mission were also made available to the public and science community immediately, allowing discoveries to be made at an incredible pace and setting a high bar for other missions. Scientists are expected to spend a decade or more in search of new discoveries in the treasure trove of data Kepler provided.

"We know the spacecraft's retirement isn't the end of Kepler's discoveries," said Jessie Dotson, Kepler's project scientist at NASA’s Ames Research Center in California’s Silicon Valley. "I'm excited about the diverse discoveries that are yet to come from our data and how future missions will build upon Kepler's results."

Before retiring the spacecraft, scientists pushed Kepler to its full potential, successfully completing multiple observation campaigns and downloading valuable science data even after initial warnings of low fuel. The latest data, from Campaign 19, will complement the data from NASA’s newest planet hunter, the Transiting Exoplanet Survey Satellite, launched in April. TESS builds on Kepler's foundation with fresh batches of data in its search of planets orbiting some 200,000 of the brightest and nearest stars to the Earth, worlds that can later be explored for signs of life by missions, such as NASA’s James Webb Space Telescope.

NASA's Ames Research Center in California's Silicon Valley manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation in Boulder, Colorado, operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

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Ball Aerospace & Technologies Corp.

Awesome Space News of the Day: Is an Exoplanet Being Orbited by a Moon the Size of Neptune?

NASA / ESA / L. Hustak

Astronomers Find First Evidence of Possible Moon Outside Our Solar System (Press Release - October 3)

Using NASA’s Hubble and Kepler space telescopes, astronomers have uncovered tantalizing evidence of what could be the first discovery of a moon orbiting a planet outside our solar system.

This moon candidate, which is 8,000 light-years from Earth in the Cygnus constellation, orbits a gas-giant planet that, in turn, orbits a star called Kepler-1625. Researchers caution that the moon hypothesis is tentative and must be confirmed by follow-up Hubble observations.

“This intriguing finding shows how NASA’s missions work together to uncover incredible mysteries in our cosmos,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate at Headquarters, Washington. “If confirmed, this finding could completely shake up our understanding of how moons are formed and what they can be made of.”

Since moons outside our solar system – known as exomoons – cannot be imaged directly, their presence is inferred when they pass in front of a star, momentarily dimming its light. Such an event is called a transit, and has been used to detect many of the exoplanets cataloged to date.

However, exomoons are harder to detect than exoplanets because they are smaller than their companion planet, and so their transit signal is weaker when plotted on a light curve that measures the duration of the planet crossing and the amount of momentary dimming. Exomoons also shift position with each transit because the moon is orbiting the planet.

In search of exomoons, Alex Teachey and David Kipping, astronomers at Columbia University in New York, analyzed data from 284 Kepler-discovered planets that were in comparatively wide orbits, longer than 30 days, around their host star. The researchers found one instance in planet Kepler-1625b, of a transit signature with intriguing anomalies, suggesting the presence of a moon.

“We saw little deviations and wobbles in the light curve that caught our attention,” Kipping said.

Based upon their findings, the team spent 40 hours making observations with Hubble to study the planet intensively – also using the transit method – obtaining more precise data on the dips of light. Scientists monitored the planet before and during its 19-hour transit across the face of the star. After the transit ended, Hubble detected a second, and much smaller, decrease in the star’s brightness approximately 3.5 hours later. This small decrease is consistent with a gravitationally-bound moon trailing the planet, much like a dog following after its owner. Unfortunately, the scheduled Hubble observations ended before the complete transit of the candidate moon could be measured and its existence confirmed.

In addition to this dip in light, Hubble provided supporting evidence for the moon hypothesis by finding the planet transit occurring more than an hour earlier than predicted. This is consistent with a planet and moon orbiting a common center of gravity that would cause the planet to wobble from its predicted location, much the way Earth wobbles as our Moon orbits it.

The researchers note the planetary wobble could be caused by the gravitational pull of a hypothetical second planet in the system, rather than a moon. While Kepler has not detected a second planet in the system, it could be that the planet is there, but not detectable using Kepler’s techniques.

“A companion moon is the simplest and most natural explanation for the second dip in the light curve and the orbit-timing deviation,” Kipping explained. “It was definitely a shocking moment to see that Hubble light curve, my heart started beating a little faster as I kept looking at that signature. But we knew our job was to keep a level head and essentially assume it was bogus, testing every conceivable way in which the data could be tricking us.”

In a paper published in the journal Science Advances, the scientists report the candidate moon is unusually large – potentially comparable to Neptune. Such large moons do not exist in our own solar system. The researchers say this may yield new insights into the development of planetary systems and may cause experts to revisit theories of how moons form around planets.

The moon candidate is estimated to be only 1.5 percent the mass of its companion planet, and the planet is estimated to be several times the mass of Jupiter. This mass-ratio is similar to the one between Earth and the Moon. In the case of the Earth-Moon system and the Pluto-Charon system, the moons are thought to be created through dust leftover after rocky planetary collisions. However, Kepler-1625b and its possible satellite are gaseous and not rocky, so the moon may have formed through a different process.

Researchers note that if this is indeed a moon, both it and its host planet lie within their star’s habitable zone, where moderate temperatures allow for the existence of liquid water on any solid planetary surface. However, both bodies are considered to be gaseous and, therefore, unsuitable for life as we know it.

Future searches for exomoons, in general, will target Jupiter-size planets that are farther from their star than Earth is from the Sun. The ideal candidate planets hosting moons are in wide orbits, with long and infrequent transit times. In this search, a moon would have been among the easiest to detect because of its large size. Currently, there are just a handful of such planets in the Kepler database. Whether future observations confirm the existence of the Kepler-1625b moon, NASA’s James Webb Space Telescope will be used to find candidate moons around other planets, with much greater detail than Kepler.

“We can expect to see really tiny moons with Webb,” Teachey said.

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