Year: 2010
Type: article
Abstract: The newly discovered planet GJ 1214b is the first known transiting super-Earth requiring a significant atmosphere to explain its observed mass and radius. Models for the structure of this planet predict that it likely possesses an H–He envelope of at least 0.05% of the total mass of the planet. However, models without a significant H–He atmosphere are not entirely ruled out by the available data. Here, we explore a range of possible atmospheres for the planet, ranging from solar composition gas, to pure CO 2 or water (steam). We present transmission and emission spectra for each of these cases. We find that, if GJ 1214b possesses a hydrogen-rich atmosphere as expected, then the primary transit depth for such an atmosphere would vary at a level of up to 0.3% as a function of wavelength, relative to the background light of its M-dwarf host star. Observations at this level of precision are potentially obtainable with current space-based instrumentation. Successful detection of the transmission signature of this planet at the ∼0.1% level would therefore provide confirmation of the hydrogen-rich nature of the planetary atmosphere. It follows that transmission spectroscopy at this level of precision could provide a first glimpse into answering the question of whether planets in the super-Earth mass regime (1–10 M ⊕ ) more closely resemble large terrestrial planets or small gas giant planets.
Authors: Eliza Miller-Ricci, Jonathan J. Fortney
Institution: University of California, Santa Cruz
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2075826795