Baptiste Klein

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?!

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

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*pre-print!

arxiv.org/abs/2508.18964

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

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!

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!

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!

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!

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... 🔭🪐🧪