Title

Thermal emission at 4.5 and 8 mu m of WASP-17b, an extremely large planet in a slightly eccentric orbit

Authors

Authors

D. R. Anderson; A. M. S. Smith; A. A. Lanotte; T. S. Barman; A. C. Cameron; C. J. Campo; M. Gillon; J. Harrington; C. Hellier; P. F. L. Maxted; D. Queloz; Ahmj Triaud;P. J. Wheatley

Comments

Authors: contact us about adding a copy of your work at STARS@ucf.edu

Abbreviated Journal Title

Mon. Not. Roy. Astron. Soc.

Keywords

methods: data analysis; techniques: photometric; occultations; planets; and satellites: atmospheres; planets and satellites: individual:; WASP-17b; stars: individual: WASP-17; TRANSITING GIANT PLANETS; SPITZER-SPACE-TELESCOPE; INFRARED ARRAY; CAMERA; EXTRASOLAR PLANETS; HOT JUPITERS; HD 189733B; RETROGRADE ORBIT; DECONVOLUTION; ATMOSPHERES; EVOLUTION; Astronomy & Astrophysics

Abstract

We report the detection of thermal emission at 4.5 and 8 mu m from the planet WASP-17b. We used Spitzer to measure the system brightness at each wavelength during two occultations of the planet by its host star. By combining the resulting light curves with existing transit light curves and radial-velocity measurements in a simultaneous analysis, we find the radius of WASP-17b to be 2.0R(Jup), which is 0.2R(Jup) larger than any other known planet and 0.7R(Jup) larger than predicted by the standard cooling theory of irradiated gas giant planets. We find the retrograde orbit of WASP-17b to be slightly eccentric, with 0.0012 < e < 0.070 (3 sigma). Such a low eccentricity suggests that, under current models, tidal heating alone could not have bloated the planet to its current size, so the radius of WASP-17b is currently unexplained. From the measured planet-star flux-density ratios we infer 4.5 and 8 mu m brightness temperatures of 1881 +/- 50 and 1580 +/- 150 K, respectively, consistent with a low-albedo planet that efficiently redistributes heat from its day side to its night side.

Journal Title

Monthly Notices of the Royal Astronomical Society

Volume

416

Issue/Number

3

Publication Date

1-1-2011

Document Type

Article

Language

English

First Page

2108

Last Page

2122

WOS Identifier

WOS:000295378100037

ISSN

0035-8711

Share

COinS