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National Aeronautics and Space
Administration
Recent Results from the Kepler Mission
Ron Gilliland - STScI - 9 June 2010
Mission Goal, Outline and Science Team
Acknowledgements
Kepler’s five year mission
is to go where no mission has gone
before
and discover strange new worlds like our own orbiting distant stars.
1.
Mission profile -- field and stars observed, data acquired.
2.
Asteroseismology.
•
3.
Context, Solar-like stars, red giants.
Other Astrophysics.
• OrbitingBill
White
Dwarfs,
Doppler
Boosting,
and
Microlensing.
Co-investigators:
Borucki
(SPI),
Dave Koch
(DSPI,
retired),
Natalie Batalha
(DSPI),
Gibor Basri, Tim Brown, Doug Caldwell, Jørgen Christensen-Dalsgaard, Bill Cochran,
Edna DeVore, Ted Dunham, John Geary, Nick Gautier, Ron Gilliland, Alan Gould, Jon
Jenkins, Yoji Kondo, Dave Latham, Jack Lissauer, Geoff Marcy, Dave Monet, &
Dimitar Sasselov.
Science Working Group: Alan Boss, John Caldwell, Andrea Dupree, Steve Howell,
Hans Kjeldsen, Søren Meibom, David Morrison, & Jill Tarter.
Participating Scientists: Derek Buzasi, Dave Charbonneau, Laurance Doyle, Eric
Ford, Jonathan Fortney, Matt Holman, Sara Seager, Jason Steffen, & Bill Welsh.
Significant others: Jason Rowe, Lars Buchhave, Howard Isaacson, Michael Endl,
Phillip MacQueen, Debra Fischer, Guillermo Torres, Steve Bryson, Mike Haas, Jessie
Dotson.
The Kepler focal plane projection
Same field is viewed throughout mission,
essentially forming a 3.5 yr movie with 30
minute
frame interval for 150,000 stars, 1 minute for
512.
Module at top center lost 9 months into
mission.
Pixels to Time Series
FOV here is 1x1 degree.
We only keep ~5% of pixels -- ‘postage-stamps’ on stars.
Prime technical driver is high duty cycle, high Signal to
Noise.
l =2, n = 20 mode
Asteroseismology of a solar-like Star.
From Time Series to Asteroseismology Inferences -- HAT-P-7
Based on Christensen-Dalsgaard et al. 2010, ApJL. Time domain processing this
page.
1: Aperture Photometry data from SOC.
3: Time series ready for
asteroseismology.
2: Detrend, fit transit, then subtract.
From Time Series to Asteroseismology Inferences -- HAT-P-7
Based on Christensen-Dalsgaard et al. 2010, ApJ, 713, L164. Frequency domain and
inferences.
A mean stellar density of
0.271 +/- 0.003 g/cm^3
results.
A fit of the stellar density,
Teff and [Fe/H] are then
made to Yonsei-Yale
evolutionary tracks arriving
at (using Brown ApJ 2010
approach):
R = 1.991 +/- 0.018 solar
M = 1.520 +/- 0.036 solar
age = 2.14 +/- 0.26 Gyr
More Solar-like stars.
Three 9th magnitude G V-IV stars with clear
oscillations.
By design these all have Teff within ~100 K of solar.
Each has an estimated mass of 1.05 to 1.1 solar with
0.1 errors.
From the top gravities range over: 4.56, 4.32, 3.84
with corresponding radii of
1.18, 1.31 and 2.1 solar.
---------------------------------Kepler has now provided 100s of detections of this
quality, theoretical interpretation is well underway, but
a large task.
Chaplin et al. 2010,
ApJL.
Oscillations in Red
Figure to right shows progression of peak power in
Giants.
oscillations for large red giants at the top at ~15
microHz to small red giants at the bottom near 240 microHz.
Oscillations are now being analyzed in detail for
~2,000
red giants allowing study of physical properties over
RGB.
PR version of Stello et al. 2010, ApJl.
Bedding, et al. 2010, ApJL.
Other Astrophysics -- Eclipsing White Dwarfs.
Doppler beaming predicted by Loeb and
Gaudi, 2003, ApJ (in Kepler context).
delta mag =
New interpretation by van Kerkwijk et al,
2010 ApJ invoking Doppler Boosting
arrives at 0.22 solar mass for secondary
(Maxted et al 2000 possible detection).
Rowe et al. 2010 ApJL -- discovery
paper of KOI-74 interpreted as 9400 K
host A star with 5.2 day orbiting WD of
13000 K, M = .02-.11, R = .04 solar.
DiStefano arXiv: 1002.3009 predicts
order 500 orbiting WDs, neutron stars,
etc will be detected by Kepler, often
relying on microlensing (Sahu &
Gilliland, 2003, ApJ).
Kepler’s view of KPD 1946+4340, a relativistic
binary star. Steven Bloemen, et al. 2010, sub.
Inferred system is a sub-dwarf B star in a
shell He burning star with a Teff of 35000 K,
mass 0.47, and radius 0.2 solar, orbited by a
16000 K, mass 0.59, radius 0.01 solar White
Dwarf. The orbital period is 0.4 days.
------------------Here a very strong Doppler beaming effect
is clearly present at the 0.1% level.
This is the first time near-field gravitational
lensing has been made use of to my
knowledge.
Star is at V = 14.28.
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Summary
Kepler is now
at end of and
year 1Look
of 3.5,Forward.
hope for 2.5 year
extension.
Planet detection and validation is in full swing -- challenging
work remains, especially in area of confirming terrestrial
candidates, and in assessing matters of completeness and
selection effects. More announcements next week.
Asteroseismology is producing spectacular results, field will be
enriched with orders of magnitude more targets with good
solutions.
Astrophysical effects such as Doppler boosting, and near-field
microlensing are being seen for the first time.
First 45 days of data become public on June 15 for 99.5% of
targets, the other 0.5% are KOIs to be released February 2011.
Cycle 2 of GO program starts ~ June 20th with 36 proposals
approved on wide range of science topics.