Journal article
A weak spectral signature of water vapour in the atmosphere of HD 179949 b at high spectral resolution in the L band
- Abstract:
- High-resolution spectroscopy (R⩾20000) is currently the only known method to constrain the orbital solution and atmospheric properties of non-transiting hot Jupiters. It does so by resolving the spectral features of the planet into a forest of spectral lines and directly observing its Doppler shift while orbiting the host star. In this study, we analyse VLT/CRIRES (R=100000) L-band observations of the non-transiting giant planet HD 179949 b centred around 3.5 μm. We observe a weak (3.0σ, or S/N = 4.8) spectral signature of H2O in absorption contained within the radial velocity of the planet at superior-conjunction, with a mild dependence on the choice of line list used for the modelling. Combining this data with previous observations in the K band, we measure a detection significance of 8.4 σ for an atmosphere that is most consistent with a shallow lapse-rate, solar C/O ratio, and with CO and H2O being the only major sources of opacity in this wavelength range. As the two sets of data were taken 3 yr apart, this points to the absence of strong radial-velocity anomalies due, e.g. to variability in atmospheric circulation. We measure a projected orbital velocity for the planet of KP = (145.2 ± 2.0) km s−1 (1σ) and improve the error bars on this parameter by ∼70 per cent. However, we only marginally tighten constraints on orbital inclination (66.2+3.7−3.1 deg) and planet mass (0.963+0.036−0.031 Jupiter masses), due to the dominant uncertainties of stellar mass and semimajor axis. Follow ups of radial-velocity planets are thus crucial to fully enable their accurate characterization via high-resolution spectroscopy.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, 7.9MB, Terms of use)
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- Publisher copy:
- 10.1093/mnras/staa715
Authors
- Publisher:
- Oxford University Press
- Journal:
- Monthly Notices of the Royal Astronomical Society More from this journal
- Volume:
- 494
- Issue:
- 1
- Pages:
- 108-119
- Publication date:
- 2020-03-14
- Acceptance date:
- 2020-03-07
- DOI:
- EISSN:
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1365-2966
- ISSN:
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0035-8711
- Language:
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English
- Keywords:
- Pubs id:
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1137441
- Local pid:
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pubs:1137441
- Deposit date:
-
2020-10-13
Terms of use
- Copyright holder:
- Webb, RK et al.
- Copyright date:
- 2020
- Rights statement:
- © 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model.
- Notes:
- This is the publisher's version of the article. The final version is available online from Oxford University Press at: https://doi.org/10.1093/mnras/staa715
- Licence:
- Other
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