Direct characterization of young giant exoplanets at high spectral resolution by coupling SPHERE and CRIRES+
Year: 2021
Type: article
Abstract: Studies of atmospheres of directly imaged extrasolar planets with high-resolution spectrographs have shown that their characterization is predominantly limited by noise on the stellar halo at the location of the studied exoplanet. An instrumental combination of high-contrast imaging and high spectral resolution that suppresses this noise and resolves the spectral lines can therefore yield higher quality spectra. We study the performance of the proposed HiRISE fiber coupling between the direct imager SPHERE and the spectrograph CRIRES+ at the Very Large Telescope for spectral characterization of directly imaged planets. Using end-to-end simulations of HiRISE we determine the signal-to-noise ratio (S/N) of the detection of molecular species for known extrasolar planets inHandKbands, and compare them to CRIRES+. We investigate the ultimate detection limits of HiRISE as a function of stellar magnitude, and we quantify the impact of different coronagraphs and of the system transmission. We find that HiRISE largely outperforms CRIRES+ for companions around bright hosts likeβPictoris or 51 Eridani. For anH = 3.5 host, we observe a gain of a factor of up to 16 in observing time with HiRISE to reach the same S/N on a companion at 200 mas. More generally, HiRISE provides better performance than CRIRES+ in 2 h integration times between 50 and 350 mas for hosts withH < 8.5 and between 50 and 700 mas forH < 7. For fainter hosts like PDS 70 and HIP 65426, no significant improvements are observed. We find that using no coronagraph yields the best S/N when characterizing known exoplanets due to higher transmission and fiber-based starlight suppression. We demonstrate that the overall transmission of the system is in fact the main driver of performance. Finally, we show that HiRISE outperforms the best detection limits of SPHERE for bright stars, opening major possibilities for the characterization of future planetary companions detected by other techniques.
Source: Astronomy and Astrophysics
Institutions: Centre National de la Recherche Scientifique, Aix-Marseille Université, Kazan State Technical University named after A. N. Tupolev, Université Côte d'Azur, Lagrange Laboratory, Observatoire de la Côte d’Azur, University of Göttingen, University of Exeter, European Southern Observatory, University of Bern
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,550
Funders: National Science Foundation, National Aeronautics and Space Administration, California Institute of Technology, European Commission, Eidgenössische Technische Hochschule Zürich, Centre National de la Recherche Scientifique, Max-Planck-Institut für Astronomie, European Research Council, Office National d'études et de Recherches Aérospatiales
OpenAlex ID: W3083162671