KOI-314c: Newfound planet is Earth-mass but gassy

KOI-314c, shown in this artist's conception, is the lightest planet to have both its mass and physical size measured. 

Surprisingly, although the planet weighs the same as Earth, it is 60 percent larger in diameter, meaning that it must have a very thick, gaseous atmosphere. 

It orbits a dim, red dwarf star (shown at left) about 200 light-years from Earth. 

KOI-314c interacts gravitationally with another planet, KOI-314b (shown in the background), causing transit timing variations that allow astronomers to measure the masses of both worlds. 

This serendipitous discovery resulted from analysis as part of the Hunt for Exomoons with Kepler (HEK) project. 

Credit: C. Pulliam & D. Aguilar (CfA)

An international team of astronomers has discovered the first Earth-mass planet that transits, or crosses in front of, its host star.

KOI-314c is the lightest planet to have both its mass and physical size measured. Surprisingly, although the planet weighs the same as Earth, it is 60 percent larger in diameter, meaning that it must have a very thick, gaseous atmosphere.

"This planet might have the same mass as Earth, but it is certainly not Earth-like," says David Kipping of the Harvard-Smithsonian Center for Astrophysics (CfA), lead author of the discovery.

"It proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants."

Kipping presented this discovery today in a press conference at the 223rd meeting of the American Astronomical Society.

The team gleaned the planet's characteristics using data from NASA's Kepler spacecraft. KOI-314c orbits a dim, red dwarf star located approximately 200 light-years away.

It circles its star every 23 days. The team estimates its temperature to be 220 degrees Fahrenheit, too hot for life as we know it.

KOI-314c is only 30 percent denser than water. This suggests that the planet is enveloped by a significant atmosphere of hydrogen and helium hundreds of miles thick.

It might have begun life as a mini-Neptune and lost some of its atmospheric gases over time, boiled off by the intense radiation of its star.

Weighing such a small planet was a challenge. Conventionally, astronomers measure the mass of an exoplanet by measuring the tiny wobbles of the parent star induced by the planet's gravity.

This radial velocity method is extremely difficult for a planet with Earth's mass. The previous record holder for a planet with a measured mass (Kepler-78b) weighed 70 percent more than Earth.

To weigh KOI-314c, the team relied on a different technique known as transit timing variations (TTV). This method can only be used when more than one planet orbits a star.

The two planets tug on each other, slightly changing the times that they transit their star.

David Nesvorny

"Rather than looking for a wobbling star, we essentially look for a wobbling planet," explains second author David Nesvorny of the Southwest Research Institute (SwRI).

"Kepler saw two planets transiting in front of the same star over and over again. By measuring the times at which these transits occurred very carefully, we were able to discover that the two planets are locked in an intricate dance of tiny wobbles giving away their masses."

The second planet in the system, KOI-314b, is about the same size as KOI-314c but significantly denser, weighing about 4 times as much as Earth.

It orbits the star every 13 days, meaning it is in a 5-to-3 resonance with the outer planet.

TTV is a very young method of finding and studying exoplanets, first used successfully in 2010. This new measurement shows the potential power of TTV, particularly when it comes to low-mass planets difficult to study using traditional techniques.

"We are bringing transit timing variations to maturity," adds Kipping.

The planet was discovered by chance by the team as they scoured the Kepler data not for exoplanets, but for exomoons.

The Hunt for Exomoons with Kepler (HEK) project, led by Kipping, scans through Kepler's planet haul looking for TTV, which can also be a signature of an exomoon.

"When we noticed this planet showed transit timing variations, the signature was clearly due to the other planet in the system and not a moon. At first we were disappointed it wasn't a moon but then we soon realized it was an extraordinary measurement," says Kipping.

Planets Found by Kepler Spacecraft Likely Larger Than Thought

The artist's concept depicts Kepler-62f, a super-Earth planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra. 

CREDIT: NASA/Ames/JPL-Caltech

A large number of worlds found by NASA's Kepler alien planet-hunting space telescope are probably significantly larger than scientists previously estimated, a new study suggests.

The Kepler Space Telescope has spotted more than 2,700 potential exoplanets since its launch in 2009, and scientists using the Kitt Peak National Observatory Mayall 4-meter telescope have categorized the home stars of many of those planet candidates for the past three years.

In particular, the researchers made detailed follow-up observations of 300 of the stars Kepler found likely to be harboring exoplanets.

"One of the main findings of this initial work is that our observations indicate that most of the stars we observed are slightly larger than previously thought and one quarter of them are at least 35 percent larger," astronomer and leader of the study Mark Everett said in a statement.

"Therefore, any planets orbiting these stars must be larger and hotter as well. By implication, these new results reduce the number of candidate Earth-size planet analogues detected by Kepler."

NASA Chandra Image: Was Kepler's supernova unusually powerful?

This composite image of Kepler's supernova remnant shows different colors ranging from lower to higher energies: red, yellow, green, blue and purple.

An optical image from the Digitized Sky Survey (pale yellow and blue) shows stars in the field. 

The Kepler supernova was a Type Ia event, the thermonuclear explosion of a white dwarf. 

New analysis suggests that the supernova explosion was not only more powerful, but might have also occurred at a greater distance, than previously thought. 

Credit: X-ray: NASA/CXC/SAO/D.Patnaude, Optical: DSS

Astronomers have long studied the Kepler supernova remnant and tried to determine exactly what happened when the star exploded to create it.

New analysis of a long observation from NASA's Chandra X-ray Observatory is providing more clues.

This analysis suggests that the supernova explosion was not only more powerful, but might have also occurred at a greater distance, than previously thought.

This image shows the Chandra data derived from more than 8 days worth of observing time. The X-rays are shown in five colours from lower to higher energies: red, yellow, green, blue, and purple.

These various X-ray slices were then combined with an optical image from the Digitized Sky Survey, showing stars in the field.

Previous analysis of this Chandra image has determined that the stellar explosion that created Kepler was what astronomers call a "Type Ia" supernova.

Illustration: NASA/CXC/M.Weiss

This class of supernovas occurs when a white dwarf gains mass, either by pulling gas off a companion star or merging with another white dwarf, until it becomes unstable and is destroyed by a thermonuclear explosion.

Unlike other well-known Type Ia supernovas and their remnants, Kepler's debris field is being strongly shaped by what it is running into.

More specifically, most Type Ia supernova remnants are very symmetrical, but the Kepler remnant is asymmetrical with a bright arc of X-ray emission in its northern region.

This indicates the expanding ball of debris from the supernova explosion is plowing into the gas and dust around the now-dead star.

Read more in the AstroPhysical Journal

NASA: First sublime planet foreshadows Mercury's fate

Now rocky planets can do this too (Image: NASA, European Space Agency, Alfred Vidal-Madjar (Institut d'Astrophysique de Paris, CNRS))

A rocky exoplanet about the size of Mercury appears to be evaporating before our eyes.

If confirmed, this would be the first time a rocky planet has been found turning to gas, demonstrating just how wacky alien planets can be.

The provocative suggestion may also foreshadow the fate of Mercury.

"My first reaction was disbelief," says Dan Fabrycky of the University of California, Santa Cruz, who was not involved in the new analysis. 

After playing with the data himself, however, he has come around – though he is still cautious. "After turning it over in my mind a few days, I cannot come up with a more natural theoretical explanation," he says.

The evaporation was inferred from observations by NASA's Kepler space telescope. These show that a star called KIC 12557548, which is slightly smaller than the sun, is dimming every 15.685 hours precisely. 

That suggests an orbiting companion is transiting, or passing in front of the star. Unlike other transits seen by Kepler, though, the dimming in this system varies wildly from one pass to another.

The best explanation is a rocky planet about the size of Mercury that is subliming – turning directly to a gas - due to the intense radiation from its star, conclude a team led by Saul Rappaport of Massachusetts Institute of Technology.

Hot rocks

The planet's orbital period suggests it is just 1 per cent of Earth's distance from the sun, where it should attain a temperature of 2000 kelvin. 

"That's well above what you would need to vaporise pyroxene and olivine – common minerals that make up rocky planets," says team member Eugene Chiang of the University of California, Berkeley.

As a result, the subliming planet is leaking rock vapour and dust into space, the team say, forming a large cloud around the planet that blocks starlight when it passes in front of the star. 

This is similar to the way sunlight vaporises ice from comets, producing a dusty cloud called a coma. The planet may even have a comet-like tail, the team say.

The cloud fluctuates in size over time, explaining why the amount of dimming varies from one event to another, they say.

No rocky planets have been seen evaporating before, although gas giants have.

Kepler discovery establishes new class of planetary systems

Using data from NASA's Kepler Mission, astronomers announced the discovery of two new transiting "circumbinary" planet systems - planets that orbit two stars.

This work establishes that such "two sun" planets are not rare exceptions, but are in fact common with many millions existing in our Galaxy.

The work was published on-line in the journal Nature and was presented by Dr. William Welsh of San Diego State University at the American Astronomical Society meeting in Austin, TX on behalf of the Kepler Science Team.

The two new planets, named Kepler-34 b and Kepler-35 b, are both gaseous Saturn-size planets.

Kepler-34 b orbits its two Sun-like stars every 289 days, and the stars themselves orbit and eclipse each other every 28 days.

The eclipses allow a very precise determination of the stars' sizes. Kepler-35 b revolves about a pair of smaller stars (80 and 89 percent of the Sun's mass) every 131 days, and the stars orbit and eclipse one another every 21 days.

Both systems reside in the constellation Cygnus, with Kepler-34 at 4900 light-years from Earth, and Kepler-35 at 5400 light-years, making these among the most distant planets discovered.

While long anticipated in both science and science fiction, the existence of a circumbinary planet orbiting a pair of normal stars was not definitively established until the discovery of Kepler-16 b, announced by the Kepler Team last September. Like Kepler-16 b, these new planets also transit (eclipse) their host stars, making their existence unambiguous.

When only Kepler-16 b was known, many questions remained about the nature of circumbinary planets - what kinds of orbits, masses, radii, temperatures, etc., could they have? And most of all, was Kepler-16 b just a fluke? With the discovery of Kepler-34 b and 35 b, astronomers can now answer many of those questions and begin to study an entirely new class of planets.

"It was once believed that the environment around a pair of stars would be too chaotic for a circumbinary planet to form, but now that we have confirmed three such planets, we know that it is possible, if not probable, that there are at least millions in the Galaxy," said Welsh, who led the team of 46 investigators involved in this research.

Dr. Laurance Doyle of the SETI Institute, co-author of this paper and lead-author of the Kepler-16 discovery, further stated, "With this paper, the new field of comparative circumbinary planetology is now established."

The discovery was made possible by the three unique capabilities of the Kepler space telescope: its ultra-high precision, its ability to simultaneously observe roughly 160,000 stars, and its long-duration near-continuous measurements of the brightness of stars. Additional work using ground-based telescopes provided velocity measurements of the stars needed to confirm that these candidates are really planets.

"The search is on for more circumbinary planets," said co-author Dr. Joshua Carter of the Harvard-Smithsonian Center for Astrophysics, "and we hope to use Kepler for years to come."

A circumbinary planet has two suns, not just one. The distances between the planet and stars are continually changing due to their orbital motion, so the amount of sunlight the planet receives varies dramatically.

"These planets can have really crazy climates that no other type of planet could have," said Dr. Jerome Orosz, a co-author from San Diego State University. "It would be like cycling through all four seasons many times per year, with huge temperature changes."

Welsh adds, "The effects of these climate swings on the atmospheric dynamics, and ultimately on the evolution of life on habitable circumbinary planets, is a fascinating topic that we are just beginning to explore."

NASA’s Kepler Spacecraft Discovers 2 Earth-Size Planets

NASA's Kepler mission announces that it's found two planets circling another star, the first ever that are Earth's size or smaller. In this artist's conception, the planet Kepler-20f, which could have an atmosphere of water vapour, is compared to Earth. (Courtesy Tim Pyle via Nature)

In what amounts to a kind of holiday gift to the cosmos, astronomers from NASA’s Kepler spacecraft announced Tuesday that they had discovered a pair of planets the size of Earth orbiting a distant star.

The new planets, one about as big as Earth, the other slightly smaller than Venus, are the smallest planets yet found beyond the solar system. Unfortunately, they are not in the 'Goldilocks' zone.

Astronomers said the discovery showed that Kepler could indeed find planets as small as our own and was an encouraging sign that planet hunters would someday succeed in the goal of finding Earth-like abodes in the heavens.

Since the first Jupiter-size exoplanets, as they are known, were discovered nearly 15 years ago astronomers have been chipping away at the sky, finding smaller and smaller planets.

“We are finally there,” said David Charbonneau, an astronomer at the Harvard-Smithsonian Center for Astrophysics, who was a member of the team that made the observations, led by his colleague Francois Fressin.

The team reported its results in an online news conference Tuesday and in a paper being published in the journal Nature.

The announcement doubled the number of known Earth-size planets in the galaxy to four from two — Earth and Venus.

The next major goal in the planetary hunt, astronomers say, is to find an Earth-size planet in the so-called Goldilocks zone of a star, where conditions are temperate for water and thus life.

The two new planets, called Kepler 20e and Kepler 20f, are far outside the Goldilocks zone — so close to the star, termed Kepler 20, that one of them is roasting at up to 1,400 degrees Fahrenheit — and are thus unlivable.

Although the milestone of an Earth-size planet had long been anticipated, astronomers on and off the Kepler team were jubilant.

Geoffrey Marcy of the University of California, Berkeley, another Kepler team member, called the new result “a watershed moment in human history.”

Debra Fischer, a planet hunter from Yale, who was not part of the team, said, “This technological feat is incredibly important because it means that the detection of Earth-sized planets at larger distances is technically possible


Read more here

SETI: Astronomers Resume Search for Intelligent Alien Life

Allen Telescope Array

CREDIT: SETI.org

Astronomers have rebooted their search for intelligent life on alien planets, and they've got thousands of targets to scan.

After hibernating for more than seven months, a set of radio telescopes run by the SETI (Search for Extraterrestrial Intelligence) Institute has once again begun listening for signals from the many alien planet candidates discovered by NASA's Kepler space telescope, researchers announced Monday (Dec. 5).

"This morning, at 6:18, we began re-observing the Kepler worlds," Jill Tarter, director of the Center for SETI Research at the SETI Institute, said Monday during the Kepler Science Conference here at NASA's Ames Research Center. "We're just extremely excited to be back on the air today."

SETI's Allen Telescope Array (ATA) is a set of 42 radio dishes located about 300 miles (500 kilometers) northeast of San Francisco. It began scanning the heavens for "technosignatures" — electromagnetic signals that could betray the presence of an intelligent alien civilization — in 2007.

SETI researchers recently started using Kepler's discoveries to guide the ATA's activities. Kepler launched in March 2009 on a mission to hunt for Earth-size planets in their parent stars' habitable zone, that just-right range of distances where liquid water — and perhaps life as we know it — could exist.

In January of this year, Tarter said, the SETI team started training the Allen array on the 54 planet candidates Kepler had detected in the habitable zone to date.

The work didn't last long, however. SETI had to shut the ATA down in April after budget problems forced the Institute's former partner, the University of California, Berkeley, to withdraw from the project.

SETI launched a crowdfunding site, www.setistars.org, in an attempt to get the array back up and running. And the public came through, donating enough money to take the ATA out of mothballs. As of Monday, citizens had chipped in more than $230,000.

Some funding help has also come from the United States Air Force, which is interested in using the array to track satellites and space debris, SETI officials said.

Many new worlds to scan
On Monday, the Kepler team announced the discovery of 1,094 new exoplanet candidates, bringing to 2,326 the total number of potential alien worlds the instrument has detected in its first 16 months of operation.

Researchers have confirmed only about 30 of these candidate planets to date, but Kepler scientists have estimated that at least 80 percent of them will end up being the real deal.

The ATA will take special interest in Kepler's candidates in the habitable zone, Tarter said. But SETI researchers hope to scan every last one of the potential planets to minimize the chances that we're blinded by our assumptions about where life "should" be.

"What we think we know actually might be a barrier to finding what is actually out there," Tarter said. "We intend to systematically explore all of these candidates."

The search of the Kepler candidates will involve scanning 9 billion different channels in a broad window of microwave frequencies. It should take two to three years, at $1.2 million per year, to search for signals from every potential alien world from the study, Tarter said.

It's exciting to focus the ATA on likely alien solar systems rather than just point the dishes toward stars and hope for the best, she added.

"We now know where to look for planets," Tarter said. "We're going to take the public's quest for technosignatures to the next level."

NASA Kepler: Planet orbits 2 Suns

This image provided by NASA shows an artist's depiction showing a discovery by NASA's Kepler mission of a world where two suns set over the horizon instead of just one.

The planet, called Kepler-16b, is the most "Tatooine-like" planet yet found in our galaxy and is depicted here with its two stars.

Tatooine is the name of Luke Skywalker's home world in the science fiction movie Star Wars.

In this case, the planet it not thought to be habitable.

It is a cold world, with a gaseous surface, but like Tatooine, it circles two stars. The largest of the two stars, a K dwarf, is about 69 percent the mass of our sun, and the smallest, a red dwarf, is about 20 percent the sun's mass.

(AP photo/NASA)

NASA Kepler Mission: Data Collection Restored

After a safe mode event that lasted 144 hours, NASA’s Kepler spacecraft returned to science data collection at 2:45 a.m. EDT Sunday, March 20.

A safe mode is a self-protective measure that the spacecraft takes when something unexpected occurs.

During safe mode, the spacecraft points the solar panels directly at the sun and begins to slowly rotate along a sun-aligned axis.

This safe mode orientation provides the vehicle with the maximum power and limits the buildup of momentum from solar wind.

The spacecraft also swapped to its backup subsystem interface box (SIB), an electronics component that provides thermal and power distribution control to all spacecraft subsystems, and powered off the photometer, the instrument used to measure light intensity to detect planets.

This is a normal procedure when the spacecraft enters safe mode.

The anomaly occurred on March 14, immediately after the spacecraft issued a network interface card (NIC) reset command to implement a computer program update. The NIC is a key component of the SIB and supports its functions.

The NIC also interfaces between the spacecraft's flight software, attitude determination, and its control subsystems and sensors. During the reset, the NIC sent invalid reaction wheel data to the flight software, which caused the spacecraft to enter safe mode.

During the spacecraft’s recovery from the safe mode event, the project team performed the spring quarterly roll and downloaded science data collected since Feb. 4 from the spacecraft's solid-state recorder.

That data will be sent to the Kepler Science Operations Center at NASA's Ames Research Center, Moffett Field, Calif., where the science team will evaluate it.

An anomaly response team will continue to evaluate the spacecraft data to determine the cause of the safe mode event.

Kepler. A Search for Habitable Planets.

Kepler. A Search for Habitable Planets.

Chandra shows when 2 Black Holes Collide

This image of NGC 6240 contains new X-ray data from Chandra (shown in red, orange, and yellow) that has been combined with an optical image from the Hubble Space Telescope originally released in 2008.

In 2002, Chandra data led to the discovery of two merging black holes, which are a mere 3,000 light years apart. They are seen as the bright point-like sources in the middle of the image.

Scientists think these black holes are in such close proximity because they are in the midst of spiraling toward each other -- a process that began about 30 million years ago. It is estimated that they holes will eventually drift together and merge into a larger black hole some tens or hundreds of millions of years from now.

Finding and studying merging black holes has become a very active field of research in astrophysics. Since 2002, there has been intense interest in follow-up observations of NGC 6240, as well as a search for similar systems. Understanding what happens when these exotic objects interact with one another remains an intriguing question for scientists.

The formation of multiple systems of supermassive black holes should be common in the universe, since many galaxies undergo collisions and mergers with other galaxies, most of which contain supermassive black holes. It is thought that pairs of massive black holes can explain some of the unusual behavior seen by rapidly growing supermassive black holes, such as the distortion and bending seen in the powerful jets they produce. Also, pairs of massive black holes in the process of merging are expected to be the most powerful sources of gravitational waves in the Universe.

The wraps are off Kepler

NASA's planet hunting Kepler telescope launched March 6. Before it can find planets, its protective dust cover had to be jettisoned. that has been done, NASA announced yesterday.

"The cover released and flew away exactly as we designed it to do," said Kepler Project Manager James Fanson of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This is a critical step toward answering a question that has come down to us across 100 generations of human history â€" are there other planets like Earth, or are we alone in the galaxy?"

Kepler's mission is to spend more than three years gazing at more than 100,000 stars in our Milky Way galaxy for signs of Earth-size planets. Some of the planets are expected to orbit in a star's "habitable zone," a warm region where water could pool on the surface.

The mission's science instrument, called a photometer, contains the largest camera ever flown in space. Its 42 charge-coupled devices (CCDs) will detect slight dips in starlight, which occur when planets passing in front of their stars partially block the light from Kepler's view.