Ground-based transit observations of the super-Earth GJ 1214 b

Caceres, C; Kabath, P; Hoyer, S; Ivanov, VD; Rojo, P; Girard, JH; Kempton, EMR; Fortney, JJ; Minniti, D


Context: GJ 1214 b is one of the few known transiting super-Earth-sized exoplanets with a measured mass and radius. It orbits an M-dwarf, only 14.55 pc away, making it a favorable candidate for follow-up studies. However, the composition of GJ 1214 b's mysterious atmosphere has yet to be fully unveiled. Aims: Our goal is to distinguish between the various proposed atmospheric models to explain the properties of GJ 1214 b: hydrogen-rich or hydrogen-He mix, or a heavy molecular weight atmosphere with reflecting high clouds, as latest studies have suggested. Methods: Wavelength-dependent planetary radii measurements from the transit depths in the optical/NIR are the best tool to investigate the atmosphere of GJ 1214 b. We present here (i) photometric transit observations with a narrow-band filter centered on 2.14 mu m and a broad-band I-Bessel filter centered on 0.8665 mu m, and (ii) transmission spectroscopy in the H and K atmospheric windows that cover three transits. The obtained photometric and spectrophotometric time series were analyzed with MCMC simulations to measure the planetary radii as a function of wavelength. We determined radii ratios of 0.1173(-0.0024)(+0.0022) for I-Bessel and 0.11735(-0.00076)(+0.00072) at 2.14 mu m. Results: Our measurements indicate a flat transmission spectrum, in agreement with last atmospheric models that favor featureless spectra with clouds and high molecular weight compositions.

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Título según WOS: Ground-based transit observations of the super-Earth GJ 1214 b
Título según SCOPUS: Ground-based transit observations of the super-Earth GJ 1214 b
Título de la Revista: ASTRONOMY & ASTROPHYSICS
Volumen: 565
Fecha de publicación: 2014
Idioma: English