Abbreviated Journal Title
infrared: planetary systems; planetary systems; planets and satellites:; individual (upsilon And b); stars: individual (upsilon And b); techniques: photometric; PLANET HD 209458B; EXTRASOLAR GIANT PLANETS; HOT JUPITERS; ATMOSPHERIC; CIRCULATION; ABSOLUTE CALIBRATION; EMISSION-SPECTRUM; SPACE-TELESCOPE; NEARBY STARS; HOST STARS; COOL STARS; Astronomy & Astrophysics
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.
Crossfield, Ian J. M.; Hansen, Brad M. S.; Harrington, Joseph; Cho, James Y. -K.; Deming, Drake; Menou, Kristen; and Seager, Sara, "A New24 Mu M Phase Curve for Upsilon Andromedae B" (2010). Faculty Bibliography 2010s. 71.