[en] We present Spitzer Space Telescope infrared photometry of a primary transit of the hot Neptune GJ 436b. The observations were obtained using the 8 mum band of the InfraRed Array Camera (IRAC). The high accuracy of the transit data and the weak limb-darkening in the 8 mum IRAC band allow us to derive (assuming M = 0.44 ± 0.04 M_o for the primary) a precise value for the planetary radius (4.19[SUP]+0.21[/SUP][SUB]-0.16[/SUB] R_â ), the stellar radius (0.463[SUP]+0.022[/SUP][SUB]-0.017[/SUB] R_o), the orbital inclination (85.90°[SUP]+0.19°[/SUP][SUB]-0.18°[/SUB]) and transit timing (2454280.78186[SUP]+0.00015[/SUP][SUB]-0.00008[/SUB] HJD). Assuming current planet models, an internal structure similar to that of Neptune with a small H/He envelope is necessary to account for the measured radius of GJ 436b. The photometric data are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/471/L51
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Gillon, Michaël ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Demory, B*-O; Observatoire de l'Université de Genève, 1290 Sauverny, Switzerland
Barman, T.; Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA
Bonfils, X.; Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
Mazeh, T.; School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
Pont, F.; Observatoire de l'Université de Genève, 1290 Sauverny, Switzerland
Udry, S.; Observatoire de l'Université de Genève, 1290 Sauverny, Switzerland
Mayor, M.; Observatoire de l'Université de Genève, 1290 Sauverny, Switzerland
Queloz, D.; Observatoire de l'Université de Genève, 1290 Sauverny, Switzerland
Language :
English
Title :
Accurate Spitzer infrared radius measurement for the hot Neptune GJ 436b
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