EDP Sciences

CO and H2O in the atmosphere of HD179949 b (Brogi et al.)

Vol. 565
In section 10. Planets and planetary systems

Carbon monoxide and water vapor in the atmosphere of the non-transiting exoplanet HD 179949 b

by M. Brogi, R. J. de Kok, J. L. Birkby, H. Schwarz, and I. A. G. Snellen, A&A 565, A124


alt

The authors have discovered two major molecules, CO and H2O, in the atmosphere of HD 179949 b, a non-transiting hot Jupiter on a three-day orbit around a warm F8 star. The detection was done with Doppler spectroscopy using CRIRES on the VLT: the planet's emission was detected Doppler-shifted with a frequency depending on the planet's orbital phase. Because the lines of these molecules were detected in absorption, this means that the atmospheric temperature profile is not inverted (i.e. warmer at higher altitudes) in this region in spite of the strong stellar irradiation. The planet's inclination and therefore its mass (0.98 Mjup) are derived, as well as a preliminary constraint on the C/O ratio which seems to be smaller than unity. Last but not least, the possibility of performing these measurements in non-transiting planets means that this is a very promising technique for studying the atmospheres of hot, close-in planets.