Volume 471, Number 3, September I 2007
|Page(s)||L51 - L54|
|Published online||30 July 2007|
Letter to the Editor
Accurate Spitzer infrared radius measurement for the hot Neptune GJ 436b*
Observatoire de l'Université de Genève, 1290 Sauverny, Switzerland e-mail: firstname.lastname@example.org
2 Institut d'Astrophysique et de Géophysique, Université de Liège, 4000 Liège, Belgium
3 Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA
4 Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
5 School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
Accepted: 21 July 2007
We present Spitzer Space Telescope infrared photometry of a primary transit of the hot Neptune GJ 436b. The observations were obtained using the 8 μm band of the InfraRed Array Camera (IRAC). The high accuracy of the transit data and the weak limb-darkening in the 8 μm IRAC band allow us to derive (assuming M = 0.44 ± 0.04 for the primary) a precise value for the planetary radius (4.19 ), the stellar radius (0.463 ), the orbital inclination (85.90°) and transit timing (2454280.78186 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.
Key words: techniques: photometric / eclipses / stars: individual: GJ 436 / planetary systems / infrared: general
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.