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Doppler shifted transient sodium detection by KECK/HIRES

Unni, Athira ; Oza, Apurva V. ; Hoeijmakers, H. Jens LU orcid ; Seidel, Julia V. ; Sivarani, Thirupathi ; Schmidt, Carl A. ; Kesseli, Aurora Y. ; de Kleer, Katherine ; Baker, Ashley D. and Gebek, Andrea , et al. (2025) In Monthly Notices of the Royal Astronomical Society: Letters 540(1). p.48-53
Abstract

We carried out the first high-resolution transit observations of the exoplanet WASP-49 Ab with Keck/HIRES. Upon custom wavelength calibration we achieve a Doppler RV precision of < 60 m s−1. . This is an improvement in RV stability of roughly 240 m s−1 with respect to the instrument standard. We report an average sodium flux residual of (Formula presented) per cent t (8.0σ) comparable to previous studies. Interestingly, an average Doppler shift of −6.2 ± 0.5 km s−1 (12.4 σ) is identified offset from the exoplanet rest frame. The velocity residuals in time trace a blueshift (Formula presented) to redshift (Formula presented) suggesting the origin of the observed sodium is unlikely from the atmosphere... (More)

We carried out the first high-resolution transit observations of the exoplanet WASP-49 Ab with Keck/HIRES. Upon custom wavelength calibration we achieve a Doppler RV precision of < 60 m s−1. . This is an improvement in RV stability of roughly 240 m s−1 with respect to the instrument standard. We report an average sodium flux residual of (Formula presented) per cent t (8.0σ) comparable to previous studies. Interestingly, an average Doppler shift of −6.2 ± 0.5 km s−1 (12.4 σ) is identified offset from the exoplanet rest frame. The velocity residuals in time trace a blueshift (Formula presented) to redshift (Formula presented) suggesting the origin of the observed sodium is unlikely from the atmosphere of the planet. The average Na light curves indicate a depth of (Formula presented) per cent(11.7 σ) enduring ≲90 min with a half-max duration of $/sim$ 40.1 min. Frequent high-resolution spectroscopic observations will be able to characterize the periodicity of the observed Doppler shifts. Considering the origin of the transient sodium gas is of unknown geometry, a co-orbiting natural satellite may be a likely source.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
exoplanets, planets and satellites: atmospheres, planets and satellites: composition, planets and satellites: gaseous planets, techniques: spectroscopic
in
Monthly Notices of the Royal Astronomical Society: Letters
volume
540
issue
1
pages
48 - 53
publisher
Oxford University Press
external identifiers
  • scopus:105003840245
ISSN
1745-3933
DOI
10.1093/mnrasl/slaf031
language
English
LU publication?
yes
id
78301b9c-f562-4da9-bbc8-9427576deefc
date added to LUP
2025-07-29 09:20:52
date last changed
2025-07-29 09:21:12
@article{78301b9c-f562-4da9-bbc8-9427576deefc,
  abstract     = {{<p>We carried out the first high-resolution transit observations of the exoplanet WASP-49 Ab with Keck/HIRES. Upon custom wavelength calibration we achieve a Doppler RV precision of &lt; 60 m s<sup>−1</sup>. . This is an improvement in RV stability of roughly 240 m s<sup>−1</sup> with respect to the instrument standard. We report an average sodium flux residual of (Formula presented) per cent t (8.0σ) comparable to previous studies. Interestingly, an average Doppler shift of −6.2 ± 0.5 km s<sup>−1</sup> (12.4 σ) is identified offset from the exoplanet rest frame. The velocity residuals in time trace a blueshift (Formula presented) to redshift (Formula presented) suggesting the origin of the observed sodium is unlikely from the atmosphere of the planet. The average Na light curves indicate a depth of (Formula presented) per cent(11.7 σ) enduring ≲90 min with a half-max duration of $/sim$ 40.1 min. Frequent high-resolution spectroscopic observations will be able to characterize the periodicity of the observed Doppler shifts. Considering the origin of the transient sodium gas is of unknown geometry, a co-orbiting natural satellite may be a likely source.</p>}},
  author       = {{Unni, Athira and Oza, Apurva V. and Hoeijmakers, H. Jens and Seidel, Julia V. and Sivarani, Thirupathi and Schmidt, Carl A. and Kesseli, Aurora Y. and de Kleer, Katherine and Baker, Ashley D. and Gebek, Andrea and Westram, Moritz Meyer zu and Fisher, Chloe and Sallum, Steph and Bestha, Manjunath and Bello-Arufe, Aaron}},
  issn         = {{1745-3933}},
  keywords     = {{exoplanets; planets and satellites: atmospheres; planets and satellites: composition; planets and satellites: gaseous planets; techniques: spectroscopic}},
  language     = {{eng}},
  number       = {{1}},
  pages        = {{48--53}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society: Letters}},
  title        = {{Doppler shifted transient sodium detection by KECK/HIRES}},
  url          = {{http://dx.doi.org/10.1093/mnrasl/slaf031}},
  doi          = {{10.1093/mnrasl/slaf031}},
  volume       = {{540}},
  year         = {{2025}},
}