NASA's Kepler Confirms 100+ Exoplanets During Its K2 Mission

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NASA's Kepler Confirms 100+ Exoplanets During Its K2 Mission
Jet Propulsion Laboratory
July 18, 2016

An international team of astronomers has discovered and confirmed a treasure
trove of new worlds using NASA's Kepler spacecraft on its K2 mission.
Out of 197 initial planet candidates, scientists have confirmed 104 planets
outside our solar system. Among the confirmed is a planetary system comprising
four promising planets that could be rocky.

These four planets, all between 20 and 50 percent larger than Earth by
diameter, are orbiting the M dwarf star K2-72, found 181 light-years away
in the direction of the Aquarius constellation. The host star is less
than half the size of the sun and less bright. The planets' orbital periods
range from five-and-a-half to 24 days, and two of them may experience
irradiation levels from their star comparable to those on Earth. Despite
their tight orbits -- closer than Mercury's orbit around our sun -- the
possibility that life could arise on a planet around such a star cannot
be ruled out, according to lead author Ian Crossfield, a Sagan Fellow
at the University of Arizona's Lunar and Planetary Laboratory in Tucson.

The researchers achieved this extraordinary "roundup" of exoplanets by
combining data with follow-up observations by Earth-based telescopes including
the North Gemini telescope and the W. M. Keck Observatory in Hawaii, the
Automated Planet Finder of the University of California Observatories,
and the Large Binocular Telescope operated by the University of Arizona.
The discoveries are published online in the Astrophysical Journal Supplement
Series.

Both Kepler and its K2 mission discover new planets by measuring the subtle
dip in a star's brightness caused by a planet passing in front of its
star. In its initial mission, Kepler surveyed just one patch of sky in
the northern hemisphere, determining the frequency of planets whose size
and temperature might be similar to Earth orbiting stars similar to our
sun. In the spacecraft's extended mission in 2013, it lost its ability
to precisely stare at its original target area, but a brilliant fix. created
a second life for the telescope that is proving scientifically fruitful.

After the fix, Kepler started its K2 mission, which has provided an ecliptic
field of view with greater opportunities for Earth-based observatories
in both the northern and southern hemispheres. Additionally, the K2 mission
is entirely community-driven with all targets proposed by the scientific
community.

Because it covers more of the sky, the K2 mission is capable of observing
a larger fraction of cooler, smaller, red-dwarf type stars, and because
such stars are much more common in the Milky Way than sun-like stars,
nearby stars will predominantly be red dwarfs.

"An analogy would be to say that Kepler performed a demographic study,
while the K2 mission focuses on the bright and nearby stars with different
types of planets," said Crossfield. "The K2 mission allows us to increase
the number of small, red stars by a factor of 20, significantly increasing
the number of astronomical 'movie stars' that make the best systems for
further study."

To validate candidate planets identified by K2, the researchers obtained
high-resolution images of the planet-hosting stars as well as high-resolution
optical spectroscopy. By dispersing the starlight as through a prism,
the spectrographs allowed the researchers to infer the physical properties
of a star -- such as mass, radius and temperature -- from which the properties
of any planets orbiting it can be inferred.

These observations represent a natural stepping stone from the K2 mission
to NASA's other upcoming exoplanet missions, such as the Transiting Exoplanet
Survey Satellite and James Webb Space Telescope.

"This bountiful list of validated exoplanets from the K2 mission highlights
the fact that the targeted examination of bright stars and nearby stars
along the ecliptic is providing many interesting new planets," said Steve
Howell, project scientist for the K2 mission at NASA's Ames Research Center
in Moffett Field, California. "These targets allow the astronomical community
ease of follow-up and characterization, providing a few gems for first
study by the James Webb Space Telescope, which could perhaps tell us about
the planets' atmospheres."

This work was performed in part under contract with the Jet Propulsion
Laboratory funded by NASA through the Sagan Fellowship Program executed
by the NASA Exoplanet Science Institute.

NASA Ames manages the Kepler and K2 missions for NASA's Science Mission
Directorate. JPL in Pasadena, California, 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 at Boulder.

For more information on the Kepler and the K2 mission, visit:

http://www.nasa.gov/kepler

For more information about exoplanets, visit:

https://exoplanets.nasa.gov/

News Media Contact
Elizabeth Landau Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425
elizabet...@jpl.nasa.gov

Michele Johnson
Ames Research Center, Moffett Field, Calif.
? 650-604-6982
michele...@nasa.gov
2016-191