Characterization of the hot Neptune GJ 436 b with Spitzer and ground-based observations

Free access article

Issue		A&A Volume 475, Number 3, December I 2007


Page(s)		1125 - 1129
Section		Planets and planetary systems
DOI		http://dx.doi.org/10.1051/0004-6361:20078354

A&A 475, 1125-1129 (2007)
DOI: 10.1051/0004-6361:20078354

Characterization of the hot Neptune GJ 436 b with Spitzer and ground-based observations

B.-O. Demory^{1, 2}, M. Gillon^{1, 3}, T. Barman⁴, X. Bonfils⁵, M. Mayor¹, T. Mazeh⁶, D. Queloz¹, S. Udry¹, F. Bouchy⁷, X. Delfosse⁸, T. Forveille⁸, F. Mallmann², F. Pepe¹, and C. Perrier⁸

¹ Observatoire de Genève, Université de Genève, 1290 Sauverny, Switzerland
e-mail: brice-olivier.demory@obs.unige.ch
² Observatoire François-Xavier Bagnoud - OFXB, 3961 Saint-Luc, Switzerland
³ Institut d'Astrophysique et de Géophysique, Université de Liège, 4000 Liège, Belgium
⁴ Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA
⁵ Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
⁶ School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
⁷ Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis Bd. Arago, 75014 Paris, France
⁸ Laboratoire d'Astrophysique de Grenoble, Observatoire de Grenoble, UMR5571 de l'Université J.Fourier et du CNRS, BP 53, 38041 Grenoble, France

(Received 25 July 2007 / Accepted 11 September 2007 )

Abstract
We present Spitzer Space Telescope infrared photometry of a secondary eclipse of the hot Neptune GJ 436 b. The observations were obtained using the 8- $\mu$ m band of the InfraRed Array Camera (IRAC). The data spanning the predicted time of secondary eclipse show a clear flux decrement with the expected shape and duration. The observed eclipse depth of 0.58 mmag allows us to estimate a blackbody brightness temperature of $T_{\rm p}$ = 717 $\pm$ 35 K at 8 $\mu$ m. We compare this infrared flux measurement to a model of the planetary thermal emission, and show that this model reproduces properly the observed flux decrement. The timing of the secondary eclipse confirms the non-zero orbital eccentricity of the planet, while also increasing its precision (e = 0.14 $\pm$ 0.01). Additional new spectroscopic and photometric observations allow us to estimate the rotational period of the star and to assess the potential presence of another planet.

Key words: techniques: photometric -- techniques: spectroscopic -- eclipses -- stars: individual: GJ 436 -- planetary systems -- infrared: general

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.