Contributed Talk - Splinter Exoplanets

Thursday, 16 September 2021, 16:45   (virtual Exo)

Deciphering Jupiter’s atmospheric chemistry as a benchmark for extrasolar gas giants using Herschel/PACS

Cyril Gapp, Miriam Rengel, Paul Hartogh, Hideo Sagawa, Helmut Feuchtgruber, Emmanuel Lellouch, Geronimo Villanueva
Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany & Georg-August-Universität Göttingen, Germany; Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany; Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany; Kyoto Sangyo University, Japan; Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany; LESIA-Observatoire de Paris, France; NASA Goddard Space Flight Center, Greenbelt, USA

On October 31, 2009, the Photodetector Array Camera and Spectrometer (PACS) onboard the Herschel Space Observatory observed far infrared (FIR) spectra of Jupiter between 55 and 200 microns at a spectral resolution ranging from 950 to 5500 depending on wavelength and grating order. These spectra included spectral lines caused by ammonia (NH3), methane (CH4), phosphine (PH3), water (H2O) and hydrogen deuteride (HD). We will present an analysis of the PACS data that contributes to a more complete understanding of the chemical composition of the Jovian atmosphere with a focus on implications for exploring extrasolar planetary systems. The analysis of the PACS data was carried out using the online radiative transfer tool Planetary Spectrum Generator (PSG) and the least squares fitting technique to infer the abundances of the trace constituents in Jupiter. The PACS data suggest high accumulations of heavy elements, such as nitrogen, phosphine and carbon in Jupiter’s deep atmosphere compared to their abundances in the Sun. This finding points towards the core accretion model applying to the formation of Jupiter, supporting the use of this broadly accepted theory for Jupiter-like planets in extrasolar planetary systems. Additionally, we obtained a new value of Jupiter’s D/H ratio as D/H = (1.5+/-0.6)x10^(-5). This ratio is consistent with previous measurements of the Jovian and the protosolar D/H ratio, supporting the scenario that accretion of icy planetesimals did not play a major role during Jupiter’s formation. Therefore, this result promotes Jupiter’s D/H ratio as a valid approximation of the protosolar one and yields further insight into the formation of the Solar System. Isotopic ratios are key diagnostic tools for the planet formation process in the solar system but also in extrasolar planetary systems. In this talk, we will present the methods and results of our data analysis and will point out implications for extrasolar research. One of our goals is to promote synergies between Solar System research and extrasolar research to stimulate interdisciplinary approaches.