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Published April 2020 | Published + Submitted
Journal Article Open

Solar Contamination in Extreme-precision Radial-velocity Measurements: Deleterious Effects and Prospects for Mitigation

Abstract

Solar contamination, due to moonlight and atmospheric scattering of sunlight, can cause systematic errors in stellar radial velocity (RV) measurements that significantly detract from the ~10 cm s−1 sensitivity required for the detection and characterization of terrestrial exoplanets in or near habitable zones of Sun-like stars. The addition of low-level spectral contamination at variable effective velocity offsets introduces systematic noise when measuring velocities using classical mask-based or template-based cross-correlation techniques. Here we present simulations estimating the range of RV measurement error induced by uncorrected scattered sunlight contamination. We explore potential correction techniques, using both simultaneous spectrometer sky fibers and broadband imaging via coherent fiber imaging bundles, that could reliably reduce this source of error to below the photon-noise limit of typical stellar observations. We discuss the limitations of these simulations, the underlying assumptions, and mitigation mechanisms. We also present and discuss the components designed and built into the NEID (NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy) precision RV instrument for the WIYN 3.5 m telescope, to serve as an ongoing resource for the community to explore and evaluate correction techniques. We emphasize that while "bright time" has been traditionally adequate for RV science, the goal of 10 cm s−1 precision on the most interesting exoplanetary systems may necessitate access to darker skies for these next-generation instruments.

Additional Information

© 2020 The American Astronomical Society. Received 2019 October 29; revised 2020 February 3; accepted 2020 February 18; published 2020 March 18. On-sky tests were conducted with the Planewave CDK 24'' Telescope operated by the Penn State Department of Astronomy & Astrophysics at Davey Lab Observatory. NEID is funded by NASA through JPL by contract 1547612. This work was partially supported by funding from the Center for Exoplanets and Habitable Worlds. The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. This work was performed by S.P.H. (in part) under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. This work was supported by NASA Headquarters under the NASA Earth and Space Science Fellowship Program through grant NNX16AO28H. This research has made use of NASA's Astrophysics Data System Bibliographic Services. Facility: DAVEY:0.6m. -

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Published - Roy_2020_AJ_159_161.pdf

Submitted - 2002.09468.pdf

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Created:
August 22, 2023
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October 19, 2023