Alex Santerne
@alexsanterne
Astronomer at Aix-Marseille University / France visiting IPAG/Grenoble. Also delegated city councilor at Gières (38) Toot a lot about Climate Change and Climate. Boycott planes, travel by train only. Opinions are my own.
Ready for the #totalsolareclipse, near León. Weather is cloud free, the spot is not so crowded. Looks gorgeous. Stay tuned for the pics 📸 #astronomy #Eclipse #eclipse2026
Si la photo a bien été prise dans les alentours du Pyla ou Arcachon, disons qu'ils ne sont pas vraiment en sécurité... contrairement à nous. On revient donc toujours sur ce déni du "ça n'arrive qu'aux autres"
Présentation aujourd'hui à la CPCN (conf des PdT·es du Comité national du CNRS) sur la transition environnementale de la recherche. Nous avons proposé une sensibilisation des sections @cnrs.fr à la transition, via Ma Terre en 180' pour une meilleure prise en compte dans l'évaluation de la recherche.
Together with the iconic system TRAPPIST-1 (@mgillon.bsky.social), this is one of the richest transiting planetary system we know so far, but with much longer orbital periods. For instance, the orbit of HIP41378 f is equivalent to Mars, while transiting its host star ! (5/6)
The last paper is by myself et al., Characterising transiting exoplanets at long orbital period: lessons learned for #PLATO from 10 years of monitoring the HIP41378 system It summaries the lessons we learned that will be important for the follow-up of PLATO planets ➡️ arxiv.org/abs/2606.22996 4/6
The second paper is by Leonardi et al., Observing a 542-day transiting giant with large TTVs: The 2025 transit of HIP 41378 f and new constraints on the outer system It reports the last transit of this unique planet using both ground- and space-based observatories ➡️ arxiv.org/abs/2606.23551 3/6
The first paper is by @sgrouffal.bsky.social et al., A decade of monitoring the HIP 41378's planetary system: Masses and orbital periods of six planets and a planet candidate This study is a result of 10 years of observation, especially with @eso.org spectrographs ➡️ arxiv.org/abs/2606.23103 2/6
Élu à la @villedegieres.bsky.social depuis quelques mois, j’ai eu l’honneur d’être officier d’état civil pour deux mariages (mes premiers) en remplacement de Mickael Guiheneuf, le maire. Ils se sont dits oui ! 👏
Proud to announce that our home is no longer using fossil fuels, at all, in our direct uses (heating, hot water, and transportation).
This last time lapse is at Sunrise, and accelerated x20 times. (4/4)
Research in astronomy in the metropolitan France is performing like a charm. (3/4)
I was astonished by the dynamism of this observatory: new domes, new instruments, new projects and new buildings. (Ok, I used to go there a lot, but that was 13 years ago, so many stuff changed) (2/4)
This week, I had the opportunity to stay 2 nights at the Pic du Midi #Observatory, in the french Pyrénées. I captured some #timelapse from this site, which is still magical. I fully support its application to the @unesco.bsky.social ! (1/4)
Je n'ai pas été très présent, ni actif ici ces dernières semaines, et ça risque de continuer. J'ai toutefois une excellente raison : je suis maintenant conseiller municipal à @villedegieres.bsky.social (1/2)
#Apero #Science Quand tu tombes sur cette question #apericube et que tu t’énerves par ce que c’est FAUX ! Cc @astropierre.com
Quand tu ouvres les fenêtres de la salle après 4h de TP d’optique, dans le noir 🤩 Le campus @ugrenoblealpes.bsky.social est vraiment splendide! 🌳🏔️
Première bonne rando @chamrousse.bsky.social sous un soleil radieux et une neige bien dure. 600m de dénivelé en un peu moins de 3h, hors pause (déjeuner à la croix de Chamrousse). 🏔️
📷 For #Christmas, even trees are wearing their most beautiful earrings #photography #blackandwhite #winter #snow See on my #flickr gallery: www.flickr.com/photos/sante...
This is an amazing app that allows you to see (almost) live all the satellites and debris (in LEO*) that are in orbit above our heads. You can pick one satellite and get many info, including its orbit. yeah, it's completely crowded, but we keep 🚀 like 📈 leolabs.space
Si vous êtes incapable d’appeler votre correspondant sans votre répertoire téléphonique 📱, n’oubliez pas qu’avant, on utilisait ça : (Retrouvé dans mes combles)
Today starts the transit of the iconic planet HIP41378 f. It occurs only once every one and half year. Here is an artist view of what the system might look like 🎃Maybe this feature could explain its unique properties ? 👻 [1/2] #Halloween #Science
Excellente soirée hier à @villedegieres.bsky.social pour le #jourdelanuit. La salle de conférence etait comble et le public nombreux pour les observations 🔭 ensuite. On a même pu faire des photos de la 🌖 au téléphone posé sur l’occulaire pour les plus téméraires à la fin. À refaire 🪐
While spin-orbit misalignments have already been observed for planet very close to their stars, this is surprising for such a long-period planet in a multi-planetary system with resonances. Hypothesis like planet-planet scattering can be ruled out here to explain planet's f obliquity. [6/8]
The Rossiter-McLaughlin effect is measuring the planet's orbital obliquity, i.e. the angle between the orbital plane and the spin axis of the star. While this angle is ~0º in the solar system, for HIP41378 it reaches Ψ=~52º. [5/8]
To overcome this issue, we set up (in 2022) a collaboration of almost all high-resolution radial-velocity spectrographs across the globe. Over the same night, all the instruments observed the target HIP41378 at the time of planet'f transit, allowing us to detect the Rossiter-McLaughlin effect. [4/8]