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

B. O. Demory, M. Gillon, T. Barman, X. Bonfils, M. Mayor, T. Mazeh, D. Queloz, S. Udry, F. Bouchy, X. Delfosse, T. Forveille, F. Mallmann, F. Pepe, C. Perrier

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


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-μm 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 TP = 717 ± 35 K at 8 μm. 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 ± 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.

Original languageEnglish (US)
Pages (from-to)1125-1129
Number of pages5
JournalAstronomy and astrophysics
Issue number3
StatePublished - Dec 2007


  • Eclipses
  • Infrared: general
  • Planetary systems
  • Stars: individual: GJ 436
  • Techniques: photometric
  • Techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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