期刊
ASTROPHYSICAL JOURNAL
卷 723, 期 2, 页码 1436-1446出版社
IOP Publishing Ltd
DOI: 10.1088/0004-637X/723/2/1436
关键词
infrared: planetary systems; planetary systems; planets and satellites: individual (upsilon And b); stars: individual (upsilon And b); techniques: photometric
资金
- NASA through JPL/Caltech
- NSF [PHY05-51164]
We report the detection of 24 mu m variations from the planet-hosting upsilon Andromedae system consistent with the orbital periodicity of the system's innermost planet, upsilon And b. We find a peak-to-valley phase curve amplitude of 0.00130 times the mean system flux. Using a simple model with two hemispheres of constant surface brightness and assuming a planetary radius of 1.3 R-J give a planetary temperature contrast of greater than or similar to 900 K and an orbital inclination of greater than or similar to 28 degrees. We further report the largest phase offset yet observed for an extrasolar planet: the flux maximum occurs similar to 80 degrees before phase 0.5. Such a large phase offset is difficult to reconcile with most current atmospheric circulation models. We improve on earlier observations of this system in several important ways: (1) observations of a flux calibrator star demonstrate the MIPS detector is stable to 10(-4) on long timescales, (2) we note that the background light varies systematically due to spacecraft operations, precluding use of this background as a flux calibrator (stellar flux measured above the background is not similarly affected), and (3) we calibrate for flux variability correlated with motion of the star on the MIPS detector. A reanalysis of our earlier observations of this system is consistent with our new result.
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