Physics
Today: NASA's
Kepler space telescope,
which was launched in March, has detected the atmosphere of a
known giant gas planet, demonstrating that it is ready to look
for new exoplanets.
The find is based on a relatively short 10 days of test data
collected before the official start of science operations.
Typically months or years of observations need to be made to
detect exoplanets."As NASA's first exoplanets mission, Kepler
has made a dramatic entrance on the planet-hunting scene," said
Jon Morse, director of the
Science
Mission Directorate's Astrophysics Division at NASA
headquarters in Washington.The results were published in
Science
magazine.Kepler team members say these new data indicate
the mission is indeed capable of finding Earth-like planets, if
they exist. Kepler will spend the next three and a half years
searching for planets.The telescope will do this by looking for
periodic dips in the brightness of stars, which occur when
orbiting planets transit, or cross in front of, the stars."When
the light curves from tens of thousands of stars were shown to
the Kepler science team, everyone was awed; no one had ever
seen such exquisitely detailed measurements of the light
variations of so many different types of stars," said
William
Borucki, the principal science investigator and lead author
of the paper.The observations were collected from a planet
called
HAT-P-7,
known to transit a star located about 1,000 light-years from
Earth. The planet orbits the star in just 2.2 days and is 26
times closer than Earth is to the Sun. Its orbit, combined with
a mass somewhat larger than the planet Jupiter, classifies this
planet as a "hot Jupiter." It is so close to its star, the
planet is as hot as the glowing red heating element on a stove.
The Kepler measurements show the transit from the previously
detected HAT-P-7. However, these new measurements are so
precise, they also show a smooth rise and fall of the light
between transits caused by the changing phases of the planet
(see right image), similar to those of our Moon. This is a
combination of both the light emitted from the planet and the
light reflected off the planet. The smooth rise and fall of
light is also punctuated by a small drop in light, called an
occultation, exactly halfway between each transit. An
occultation happens when a planet passes behind a star.The new
Kepler data can be used to study this hot Jupiter in
unprecedented detail. The depth of the occultation and the
shape and amplitude of the light curve show the planet has an
atmosphere with a day-side temperature of about 2376
°Celsius. Little of this heat is carried to the cool night
side. The occultation time compared to the main transit time
shows the planet has a circular orbit. The discovery of light
from this planet confirms the predictions by researchers and
theoretical models that the emission would be detectable by
Kepler.The observed brightness variation is just one and a half
times what is expected for a transit caused by an Earth-sized
planet. Although this is already the highest precision ever
obtained for an observation of this star, Kepler will be even
more precise after analysis software being developed for the
mission is completed."This early result shows the Kepler
detection system is performing right on the mark," said David
Koch, deputy principal investigator of NASA's Ames Research
Center at Moffett Field, California. "It bodes well for
Kepler's prospects to be able to detect Earth-size planets."
Related Link
Kepler's
Optical Phase Curve of the Exoplanet HAT-P-7b
The find is based on a relatively short 10 days of test data
collected before the official start of science operations.
Typically months or years of observations need to be made to
detect exoplanets."As NASA's first exoplanets mission, Kepler
has made a dramatic entrance on the planet-hunting scene," said
Jon Morse, director of the
Science
Mission Directorate's Astrophysics Division at NASA
headquarters in Washington.The results were published in
Science
magazine.Kepler team members say these new data indicate
the mission is indeed capable of finding Earth-like planets, if
they exist. Kepler will spend the next three and a half years
searching for planets.The telescope will do this by looking for
periodic dips in the brightness of stars, which occur when
orbiting planets transit, or cross in front of, the stars."When
the light curves from tens of thousands of stars were shown to
the Kepler science team, everyone was awed; no one had ever
seen such exquisitely detailed measurements of the light
variations of so many different types of stars," said
William
Borucki, the principal science investigator and lead author
of the paper.The observations were collected from a planet
called
HAT-P-7,
known to transit a star located about 1,000 light-years from
Earth. The planet orbits the star in just 2.2 days and is 26
times closer than Earth is to the Sun. Its orbit, combined with
a mass somewhat larger than the planet Jupiter, classifies this
planet as a "hot Jupiter." It is so close to its star, the
planet is as hot as the glowing red heating element on a stove.
The Kepler measurements show the transit from the previously
detected HAT-P-7. However, these new measurements are so
precise, they also show a smooth rise and fall of the light
between transits caused by the changing phases of the planet
(see right image), similar to those of our Moon. This is a
combination of both the light emitted from the planet and the
light reflected off the planet. The smooth rise and fall of
light is also punctuated by a small drop in light, called an
occultation, exactly halfway between each transit. An
occultation happens when a planet passes behind a star.The new
Kepler data can be used to study this hot Jupiter in
unprecedented detail. The depth of the occultation and the
shape and amplitude of the light curve show the planet has an
atmosphere with a day-side temperature of about 2376
°Celsius. Little of this heat is carried to the cool night
side. The occultation time compared to the main transit time
shows the planet has a circular orbit. The discovery of light
from this planet confirms the predictions by researchers and
theoretical models that the emission would be detectable by
Kepler.The observed brightness variation is just one and a half
times what is expected for a transit caused by an Earth-sized
planet. Although this is already the highest precision ever
obtained for an observation of this star, Kepler will be even
more precise after analysis software being developed for the
mission is completed."This early result shows the Kepler
detection system is performing right on the mark," said David
Koch, deputy principal investigator of NASA's Ames Research
Center at Moffett Field, California. "It bodes well for
Kepler's prospects to be able to detect Earth-size planets."
Related Link
Kepler's
Optical Phase Curve of the Exoplanet HAT-P-7b
