Institute of Astronomy

Elemental abundances in exoplanetary atmospheres and lessons across the HR diagram

SpeakerTalk DateTalk Series
Nikku Madhusudhan1 August 2014Across HR 2014 Talks


Spectroscopic observations of extrasolar planets in the past few years have led to the possibility of determining elemental abundance ratios in their atmospheres. Nominal constraints on atmospheric C/O ratios have already been reported for a few hot Jupiters. In the present work, we combine existing data from the Spitzer Space Telescope with new data obtained using the Hubble Space Telescope and ground-based facilities to place stringent constraints on the atmospheric elemental abundances for six transiting exoplanets. These planets are representative of the range of the irradiated exoplanet population in sizes and temperatures. We use our estimates of these elemental abundance ratios to place the first rigorous constraints on the formation and evolutionary conditions of close-in exoplanets, and study the correlations of their formation histories with their stellar and orbital parameters. We also compare the elemental abundances we derive for exoplanets around main sequence stars to those derived for young directly-imaged exoplanets and protoplanetary disks, as well as to those inferred from debris disks and pollution signatures in white dwarf spectra. Based on these comparisons, we discuss some insights into planetary compositions across the HR diagram.