Webb, RK;
Brogi, M;
Gandhi, S;
Line, MR;
Birkby, JL;
Chubb, K;
Snellen, IAG;
(2020)
A weak spectral signature of water vapour in the atmosphere of HD 179949 b at high spectral resolution in the L band.
Monthly Notices of the Royal Astronomical Society
, 494
(1)
pp. 108-119.
10.1093/mnras/staa715.
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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.
| Type: | Article |
|---|---|
| Title: | A weak spectral signature of water vapour in the atmosphere of HD 179949 b at high spectral resolution in the L band |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/staa715 |
| Publisher version: | https://doi.org/10.1093/mnras/staa715 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, techniques: spectroscopic, planets and satellites: atmospheres, planets and satellites: fundamental parameters, planets and satellites: individual: HD 179949b, ORBITAL MOTION, NEARBY STARS, PLANET, SPECTROSCOPY, CANDIDATE, EVOLUTION, RATIO |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10100506 |
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