Exoplanets

NASA Kepler Visionary Honored By American Association for the Advancement of Science

William J. Borucki, principal investigator for NASA's Kepler mission at the agency's Ames Research Center in Silicon Valley, California, has been named a Fellow by the American Association for the Advancement of Science (AAAS).

Borucki is recognized for distinguished contributions to the field of astrophysics, with his leadership of the Kepler Mission leading to the discovery of thousands of exoplanets.

"This is a worthy acknowledgment of Bill Borucki's vision and the commitment of the Kepler mission team," said Michael Bicay, director for science at Ames. “Kepler has re-written the narrative in contemporary astronomy by proving what scientists long suspected—that planets are common in our Milky Way galaxy. This essential leap in knowledge allows us to take the next important steps in ascertaining whether life could exist elsewhere."

Click to see large imageKepler is the first NASA mission to find Earth-size planets in the habitable zone--the region in a planetary system where liquid water might pool on the surface of an orbiting planet. To date, Kepler has identified more than 5,100 planet candidates, of which more than 2,500 have been verified as bona fide planets confirming that planets are everywhere.

Beginning in 1992, with the first proposal for the Kepler mission to NASA Headquarters, Borucki led a determined team through a decade of tackling questions about technology that had not been flown in space yet. With the final concerns addressed, the mission once deemed impossible was approved for flight in 2000. 

"I am truly honored to be named a fellow by an organization that has a proud history of promoting advances in the sciences," said Borucki. 

Borucki will be presented with an official certificate and a gold and blue (representing science and engineering, respectively) rosette pin at a ceremony Feb. 18, 2017 at the 2017 AAAS Annual Meeting in Boston, Massachussetts.

Previous honors Borucki has received include the 2016 Franklin Institute Bower Award and Prize; the 2015 Shaw Prize; the 2013 Samuel J. Heyman Service to America Medals presented by United States President Obama; and the 2013 Henry Draper Medal.

Borucki earned a Master of Science degree in physics from the University of Wisconsin at Madison in 1962 and joined Ames as a space scientist that same year. The results of Borucki's early work developing spectroscopic instrumentation to determine the plasma properties of hypervelocity shock waves was used in the design of the heat shields for the Apollo mission. In July 2015, Borucki retired from NASA after 52 years of service at the agency. 

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

For more information about the Kepler and K2 missions, visit:

http://www.nasa.gov/kepler

For more information on the AAAS Fellows program, visit:

https://www.aaas.org/program/aaas-fellows

AWARDS FOR EXOPLANET RESEARCH

MOUNTAIN VIEW – Three SETI Institute scientists have received NASA’s most prestigious honors for their work in the burgeoning field of exoplanet research.

Jeff Coughlin is the recipient of the space agency’s Exceptional Engineering Achievement medal. Jason Rowe and Christopher Burke are being awarded the Exceptional Scientific Achievement Medal.

All three are team members for the Kepler Mission, one of the most successful science experiments of recent times.  Kepler has discovered thousands of exoplanets – worlds orbiting other stars.  These researchers were as important to its success as the shipwrights building the Nina, Pinta and Santa Maria were to the European discovery of America.


NASA's Kepler mission has verified 1,284 new planets – the single largest finding of planets to date.

Coughlin led the group that developed a technique for fully automating the extraction of planetary candidates from Kepler data. During the first six years of the mission, these candidates were manually selected from the roughly 20,000 observed transit-like signals.  But because human judgment varies among individuals, the catalog was both non-uniform and compromised by errors. 

“We turned candidate recognition into a task for computers,” says Coughlin.  “We were able to teach the computer to do what the humans did, but without the bias or the variability.”

Using synthetic data, Coughlin’s team was able to verify the performance of his digital analyzer, and found that it had an accuracy of 97 – 99 percent, something that was unimaginable with humans in the loop.

Jason Rowe’s work focused on deciding which of the exoplanet candidates found by Kepler were indeed actual planets.  In the past, this generally involved measuring stellar radial velocities with large, ground-based telescopes.  The one-by-one scheme was a bottleneck that limited confirmations to no more than 200 per year, world-wide.  Rowe developed a statistical analysis called validation by multiplicity which allows bulk checking of planets by the hundreds.  In 2014, his work resulted in the validation of 715 new exoplanets, doubling the number that were known.

“The validation of candidates via multiplicity allowed us to shift planet discovery into high gear,” notes Rowe.  “It’s the difference between building something in your garage and industrial production.”

While Kepler has discovered thousands of planets, it’s a very biased sample, favoring large planets, tight orbits, and small host stars.  Christopher Burke developed a method to remove and correct for these biases in order to ascertain what is the actual distribution of planets – and in particular, what fraction of Sun-like stars are orbited by Earth-size worlds in the habitable zone. 


Since Kepler launched in 2009, 21 planets less than twice the size of Earth have been discovered in the habitable zones of their stars. The orange spheres represent the nine newly validated planets announcement on May 10, 2016. The blue disks represent the 12 previous known planets. These planets are plotted relative to the temperature of their star and with respect to the amount of energy received from their star in their orbit in Earth units. The sizes of the exoplanets indicate the sizes relative to one another. The images of Earth, Venus and Mars are placed on this diagram for reference. The light and dark green shaded regions indicate the conservative and optimistic habitable zone. Credits: NASA Ames/N. Batalha and W. Stenzel

“Unlike our Solar System, with its inner rocky worlds and outer giants, Kepler has found that the galaxy teems with a rich diversity of planets,” Burke says.  “Rocky planets mingle with giant planets on short orbital periods, and planets of in-between size are common.”

At present, his analysis suggests a large population of planets like Earth, although more work is still needed to confirm this result.

A century from now, the present decade will be celebrated as the one in which researchers finally made an inventory of the planets that fill the cosmos.  It is a very special time for astronomy, and these awards are a tribute to some of the key scientists who made it happen.

Research Thrust: 

Exiled exoplanet possibly kicked out of star's local neighborhood

Berkeley — A planet discovered last year sitting at an unusually large distance from its star – 16 times farther than Pluto is from the sun – may have been kicked out of its birthplace close to the star in a process similar to what may have happened early in our own solar system’s history. 

Images from the Gemini Planet Imager (GPI) in the Chilean Andes and the Hubble Space Telescope show that the star has a lopsided comet belt indicative of a very disturbed solar system, and hinting that the planet interactions that roiled the comets closer to the star might have sent the exoplanet into exile as well.

The planet may even have its own ring of debris it dragged along with it when it was expelled.

“We think that the planet itself could have captured material from the comet belt, and that the planet is surrounded by a large dust ring or dust shroud,” said Paul Kalas, an adjunct professor of astronomy at UC Berkeley. “We conducted three tests and found tentative evidence for a dust cloud, but the jury is still out.”

“The measurements we made on the planet suggest it may be dustier than comparison objects, and we are making follow-up observations to check if the planet is really encircled by a disk – an exciting possibility,” said Abhi Rajan, a graduate student at Arizona State University who analyzed the planet images.

Such planets are of interest because in its youth, our own solar system may have had planets that were kicked out of the local neighborhood and are no longer among of the eight planets we see today.

“Is this a picture of our solar system when it was 13 million years old?” asks Kalas. “We know that our own belt of comets, the Kuiper belt, lost a large fraction of its mass as it evolved, but we don’t have a time machine to go back and see how it was decimated. One of the ways, though, is to study these violent episodes of gravitational disturbance around other young stars that kick out many objects, including planets.”

The disturbance could have been caused by a passing star that perturbed the inner planets, or a second massive planet in the system. The GPI team also looked for another large planet closer to the star that may have interacted with the exoplanet, but found nothing outside of a Uranus-sized orbit.
 
Kalas and Rajan will discuss the observations during a Google+ Hangout On Air at 7 a.m. Hawaii time (noon EST) on Dec. 1 during Extreme Solar Systems III, the third in a series of international meetings on exoplanets that this year takes place on the 20 anniversary of the discovery of the first exoplanet in 1995. Viewers without Google+ accounts may participate via YouTube.

A paper about the results, with Kalas as lead author, was published in the The Astrophysical Journal on November 20, 2015.

Young, 13-million-year-old star

The star, HD 106906, is located 300 light years away in the direction of the constellation Crux and is similar to the sun, but much younger: about 13 million years old, compared to our sun’s 4.5 billion years. Planets are thought to form early in a stars history, however, and in 2014 a team led by Vanessa Bailey at the University of Arizona discovered a planet HD 106906 b around the star weighing a hefty 11 times Jupiter’s mass and located in the star’s distant suburbs, an astounding 650 AU from the star (one AU is the average distance between Earth and the sun, or 93 million miles).

Planets were not thought to form so far from their star and its surrounding protoplanetary disk, so some suggested that the planet formed much like a star, by condensing from its own swirling cloud of gas and dust. The GPI and Hubble discovery of a lopsided comet belt and possible ring around the planet points instead to a normal formation within the debris disk around the star, but a violent episode that forced it into a more distant orbit.

Kalas and a multi-institutional team using GPI first targeted the star in search of other planets in May 2015 and discovered that it was surrounded by a ring of dusty material very close to the size of our own solar system’s Kuiper Belt. The emptiness of the central region – an area about 50 AU in radius, slightly larger than the region occupied by planets in our solar system – indicates that a planetary system has formed there, Kalas said. 

He immediately reanalyzed existing images of the star taken earlier by the Hubble Space Telescope and discovered that the ring of dusty material extended much farther away and was extremely lopsided. On the side facing the planet, the dusty material was vertically thin and spanned nearly the huge distance to the known planet, but on the opposite side the dusty material was vertically thick and truncated.

“These discoveries suggest that the entire planetary system has been recently jostled by an unknown perturbation to its current asymmetric state,” he said. The planet is also unusual in that its orbit is possibly tilted 21 degrees away from the plane of the inner planetary system, whereas most planets typically lie close to a common plane.

Kalas and collaborators hypothesized that the planet may have originated from a position closer to the comet belt, and may have captured dusty material that still orbits the planet. To test the hypothesis, they carefully analyzed the GPI and Hubble observations, revealing three properties about the planet consistent with a large dusty ring or shroud surrounding it. However, for each of the three properties, alternate explanations are possible.

The investigators will be pursuing more sensitive observations with the Hubble Space Telescope to determine if HD 106906b is in fact one of the first exoplanets that resembles Saturn and its ring system.

The inner belt of dust around the star has been confirmed by an independent team using the planet-finding instrument SPHERE on the ESO’s Very Large Telescope in Chile. The lopsided nature of the debris disk was not evident, however, until Kalas called up archival images from Hubble’s Advanced Camera for Surveys.

The GPI Exoplanet Survey, operated by a team of astronomers at UC Berkeley and 23 other institutions, is targeting 600 young stars, all less than approximately 100 million years old, to understand how planetary systems evolve over time and what planetary dynamics could shape the final arrangement of planets like we see in our solar system today.

Among Kalas’s coauthors are UC Berkeley graduate student Jason Wang and ASU graduate student Abhijath Rajan. The research was supported by the NSF and NASA’s Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA’s Science Mission Directorate.

Research Thrust: 

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