High-resolution spectroscopic search for the thermal emission of the extrasolar planet HD 217107 b

摘要

We analyzed the combined near-infrared spectrum of a star-planet system withthermal emission atmospheric models, based on the composition and physicalparameters of the system. The main objective of this work is to obtain theinclination of the orbit, the mass of the exoplanet, and the planet-to-starflux ratio. We present the results of our routines on the planetary system HD217107, which was observed with the high-resolution spectrograph Phoenix at2.14 microns. We revisited and tuned a correlation method to directly searchfor the high-resolution signature of a known non-transiting extrasolar planet.We could not detect the planet with our current data, but we presentsensitivity estimates of our method and the respective constraints on theplanetary parameters. With a confidence level of 3--$\sigma$ we constrain theHD 217107 b planet-to-star flux ratio to be less than $5 \times 10^{-3}$. Wealso carried out simulations on other planet candidates to assess thedetectability limit of atmospheric water on realistically simulated data setsfor this instrument, and we outline an optimized observational and selectionstrategy to increase future probabilities of success by considering the optimalobserving conditions and the most suitable candidates.