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Doppler tomography as a tool for detecting exoplanet atmospheres
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Watson, C. A., de Mooij, E. J. W., Steeghs, D., Marsh, Tom, Brogi, Matteo, Gibson, N. P. and Matthews, S. (2019) Doppler tomography as a tool for detecting exoplanet atmospheres. Monthly Notices of the Royal Astronomical Society, 490 (2). pp. 1991-2006. doi:10.1093/mnras/stz2679 ISSN 0035-8711.
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Official URL: https://doi.org/10.1093/mnras/stz2679
Abstract
High-resolution Doppler spectroscopy is a powerful tool for identifying molecular species in the atmospheres of both transiting and non-transiting exoplanets. Currently, such data is analysed using cross-correlation techniques to detect the Doppler shifting signal from the orbiting planet. In this paper we demonstrate that, compared to cross-correlation methods currently used, the technique of Doppler tomography has improved sensitivity in detecting the subtle signatures expected from exoplanet atmospheres. This is partly due to the use of a regularizing statistic, which acts to suppress noise, coupled to the fact that all the data is fit simultaneously. In addition, we show that the technique can also effectively suppress contanimating spectral features that may arise due to overlapping lines, repeating line patterns, or the use of incorrect linelists. These issues can confuse conventional cross-correlation approaches, primarily due to aliasing issues inherent in such techniques, whereas Doppler tomography is less susceptible to such effects. In particular, Doppler tomography shows exceptional promise for simultaneously detecting multiple line species (e.g. isotopologues), even when there are high contrasts between such species – and far outperforms current CCF analyses in this respect. Finally, we demonstrate that Doppler tomography is capable of recovering molecular signals from exoplanets using real data, by confirming the strong detection of CO in the atmosphere of τ Boo b. We recover a signal with a planetary radial velocity semi-amplitude Kp = 109.6 ± 2.2 km s−1, in excellent agreement with the previously reported value of 110.0 ± 3.2 km s−1.
Item Type: | Journal Article | |||||||||
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Subjects: | Q Science > QB Astronomy T Technology > TK Electrical engineering. Electronics Nuclear engineering |
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | |||||||||
SWORD Depositor: | Library Publications Router | |||||||||
Library of Congress Subject Headings (LCSH): | Doppler radar, Astronomical spectroscopy , Extrasolar planets , Extrasolar planets -- Detection, Extrasolar planets -- Atmospheres | |||||||||
Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society | |||||||||
Publisher: | Oxford University Press | |||||||||
ISSN: | 0035-8711 | |||||||||
Official Date: | December 2019 | |||||||||
Dates: |
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Volume: | 490 | |||||||||
Number: | 2 | |||||||||
Page Range: | pp. 1991-2006 | |||||||||
DOI: | 10.1093/mnras/stz2679 | |||||||||
Status: | Peer Reviewed | |||||||||
Publication Status: | Published | |||||||||
Access rights to Published version: | Restricted or Subscription Access | |||||||||
Date of first compliant deposit: | 29 October 2019 | |||||||||
Date of first compliant Open Access: | 29 October 2019 | |||||||||
RIOXX Funder/Project Grant: |
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