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Baptiste Klein

@astroklein

Postdoc on Exoplanets and Stellar activity at Oxford

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16.07.2025
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Latest posts by Baptiste Klein @astroklein

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VLT/CRIRES+ observations of warm Neptune WASP-107 b: Molecular detections and challenges in ground-based transmission spectroscopy of cooler and cloudy exoplanets Atmospheres of transiting exoplanets can be studied spectroscopically using space-based or ground-based observations. Each has its own strengths and weaknesses, so there are benefits to both approache...

Do you love WASP-107 b? Do you love making use of *both* ground VLT + space JWST obs to detect molecules in a "warm" (Teq<800K) #exoplanet in transmission, even in a crazy confusing cloudy atmosphere?!

๐Ÿšจ It's PAPER* DAY! Which means #scicomm thread!

๐Ÿงตโฌ‡๏ธ๐Ÿ”ญ๐Ÿช๐Ÿงช

*pre-print!

arxiv.org/abs/2508.18964

27.08.2025 10:37 ๐Ÿ‘ 36 ๐Ÿ” 9 ๐Ÿ’ฌ 3 ๐Ÿ“Œ 2

Big thanks to HARPS-N solar team and science team, and to TNG staff for processing the data and maintaining the solar telescope!!

28.08.2025 14:01 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

Could Doppler Imaging be a reliable alternative to radial-velocity-based activity modelling techniques? Maybe.. but we will have a develop an operational version of the code! Please contact me if you want to collaborate on this!

28.08.2025 14:01 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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We inject exoplanet signatures into the HARPS-N solar spectra, and use Doppler Imaging to retrieve these whilst modelling stellar activity. We show that, in the case of a super Earth on a 100-day orbit, the mass is retrieved with an accuracy at least as good as 2D Gaussian Processes!

28.08.2025 14:01 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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Our code pick up quite well the large structures of disc-resolved Dopplergrams of the Sun with SDO/HMI! Understanding what exact physical is picked up will need more work though!

28.08.2025 14:01 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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In Doppler Imaging, we model the distortions of a star's spectral lines caused by magnetically-active regions at the stellar surface. We invert them into a full low-resolution map of the stellar surface brightness. We bypass the radial velocity computation!

28.08.2025 14:01 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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Very excited to share that my new paper has been accepted for publication in MNRAS!
We are applying Doppler Imaging to model the activity signals from the HARPS-N Sun-as-a-star spectra! We show that injected planets can be retrieved with great accuracy!
ui.adsabs.harvard.edu/abs/2025MNRA... ๐Ÿ”ญ๐Ÿช๐Ÿงช

28.08.2025 14:01 ๐Ÿ‘ 19 ๐Ÿ” 6 ๐Ÿ’ฌ 2 ๐Ÿ“Œ 1