Trent J. Perrotto
Headquarters, Washington
202-358-0321
trent.j.perrotto@nasa.gov
Michele Johnson
Ames Research Center, Moffett Field, Calif.
650-604-6982
michele.johnson@nasa.gov
RELEASE: 12-032
NASA'S KEPLER ANNOUNCES 11 PLANETARY SYSTEMS HOSTING 26 PLANETS
MOFFET FIELD, Calif. -- NASA's Kepler mission has discovered 11 new
planetary systems hosting 26 confirmed planets. These discoveries
nearly double the number of verified planets and triple the number of
stars known to have more than one planet that transits, or passes in
front of, the star. Such systems will help astronomers better
understand how planets form.
The planets orbit close to their host stars and range in size from 1.5
times the radius of Earth to larger than Jupiter. Fifteen are between
Earth and Neptune in size. Further observations will be required to
determine which are rocky like Earth and which have thick gaseous
atmospheres like Neptune. The planets orbit their host star once
every six to 143 days. All are closer to their host star than Venus
is to our sun.
"Prior to the Kepler mission, we knew of perhaps 500 exoplanets across
the whole sky," said Doug Hudgins, Kepler program scientist at NASA
Headquarters in Washington. "Now, in just two years staring at a
patch of sky not much bigger than your fist, Kepler has discovered
more than 60 planets and more than 2,300 planet candidates. This
tells us that our galaxy is positively loaded with planets of all
sizes and orbits."
Kepler identifies planet candidates by repeatedly measuring the change
in brightness of more than 150,000 stars to detect when a planet
passes in front of the star. That passage casts a small shadow toward
Earth and the Kepler spacecraft.
Each of the new confirmed planetary systems contains two to five
closely spaced transiting planets. In tightly packed planetary
systems, the gravitational pull of the planets on each other causes
some planets to accelerate and some to decelerate along their orbits.
The acceleration causes the orbital period of each planet to change.
Kepler detects this effect by measuring the changes, or so-called
Transit Timing Variations (TTVs
Planetary systems with TTVs can be verified without requiring
extensive ground-based observations, accelerating confirmation of
planet candidates. The TTV detection technique also increases
Kepler's ability to confirm planetary systems around fainter and more
distant stars.
Five of the systems (Kepler-25, Kepler-27, Kepler-30, Kepler-31 and
Kepler-33) contain a pair of planets where the inner planet orbits
the star twice during each orbit of the outer planet. Four of the
systems (Kepler-23, Kepler-24, Kepler-28 and Kepler-32) contain a
pairing where the outer planet circles the star twice for every three
times the inner planet orbits its star.
"These configurations help to amplify the gravitational interactions
between the planets, similar to how my sons kick their legs on a
swing at the right time to go higher," said Jason Steffen, the
Brinson postdoctoral fellow at Fermilab Center for Particle
Astrophysics in Batavia, Ill., and lead author of a paper confirming
four of the systems.
Kepler-33, a star that is older and more massive than our sun, had the
most planets. The system hosts five planets, ranging in size from 1.5
to 5 times that of Earth. All of the planets are located closer to
their star than any planet is to our sun.
The properties of a star provide clues for planet detection. The
decrease in the star's brightness and duration of a planet transit,
combined with the properties of its host star, present a recognizable
signature. When astronomers detect planet candidates that exhibit
similar signatures around the same star, the likelihood of any of
these planet candidates being a false positive is very low.
"The approach used to verify the Kepler-33 planets shows the overall
reliability is quite high," said Jack Lissauer, planetary scientist
at NASA Ames Research Center at Moffett Field, Calif., and lead
author of the paper on Kepler-33. "This is a validation by
multiplicity."
These discoveries are published in four different papers in the
Astrophysical Journal and the Monthly Notices of the Royal
Astronomical Society.
Ames manages Kepler's ground system development, mission operations
and science data analysis. NASA's Jet Propulsion Laboratory,
Pasadena, Calif., managed the Kepler mission's development.
For more information about the Kepler mission and to view the digital
press kit, visit:
-end-
To subscribe to the list, send a message to:
hqnews-subscribe@mediaservices.nasa.gov
To remove your address from the list, send a message to:
hqnews-unsubscribe@mediaservices.nasa.gov
No comments:
Post a Comment