Title

A NEW24 mu m PHASE CURVE FOR upsilon ANDROMEDAE b

Authors

Authors

I. J. M. Crossfield; B. M. S. Hansen; J. Harrington; J. Y. K. Cho; D. Deming; K. Menou;S. Seager

Comments

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Abbreviated Journal Title

Astrophys. J.

Keywords

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

Abstract

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.

Journal Title

Astrophysical Journal

Volume

723

Issue/Number

2

Publication Date

1-1-2010

Document Type

Article

Language

English

First Page

1436

Last Page

1446

WOS Identifier

WOS:000284093700039

ISSN

0004-637X

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