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Author: ktj

Conference: Heraeus-Seminar on the heliosphere, astrospheres and exoplanets ?>

Conference: Heraeus-Seminar on the heliosphere, astrospheres and exoplanets

Last week a huge delegation from my group attended the international Heraeus-Seminar “From the Heliosphere to Astrospheres – Lessons for Exoplanets and their Habitability” in Bad Honnef, Germany (conference website). We had contributed talks given by my group members Judy Chebly and Nikoleta Ilic, plus contributed talks by my group’s guests Yu Xu and Florian Rünger; posters given by Eliana Amazo-Gomez and Joana Wokittel; and three (!) invited talks by Ekaterina Ilin, Julian Alvarado-Gomez and myself. Unfortunately I became sick…

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Paper on host star activity and the exoplanet radius gap ?>

Paper on host star activity and the exoplanet radius gap

Laura Ketzer, one of my PhD students, recently published a detailed study on the fate of small exoplanets – super-Earths and mini-Neptunes – under different time evolutions of the magnetic activity of the host star. The so-called radius gap manisfests itself differently for stars that experience an early versus a late spin-down. Also in samples of mixed stellar spin-down histories the features of the gap as a whole change with age, so that uniform age samples, such as open stellar…

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Paper on tidal star-planet interactions ?>

Paper on tidal star-planet interactions

My PhD student Nikoleta Ilic has published a project we have been working on for the past two years: the identification of tidal star-planet interaction in a sample of planet-hosting stars. The tidal interaction leads to a spin-up of the host stars, which we identified through comparisons with co-eval companion stars in wide orbits around the star-planet systems. The paper was also featured in a joint press release of the AIP and the Harvard-Smithsonian Center for Astrophysics: https://chandra.harvard.edu/press/22_releases/press_110222.html Ilic, N….

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Instrumentation projects presented at SPIE ?>

Instrumentation projects presented at SPIE

My group is involved in two instrumentation projects that presented updates at the recent SPIE conference: the ANDES spectrograph for the ELT, where we at the AIP are responsible for the design and the construction of its UBV arm; and ARCUS, a concept for a high spectral resolution X-ray space telescope, where I am involved in the exoplanet science goals. The SPIE proceedings for both projects can be found here: Marconi et al., “ANDES, the high resolution spectrograph for the…

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Completed PhD theses ?>

Completed PhD theses

Two PhD students successfully defended their PhD theses after the summer break: Dr. Grace Foster completed her thesis and defense on “X-ray studies of exoplanet systems” in August 2022; Dr. Ekaterina Ilin completed her thesis and defense on “High lights: stellar flares as probes of magnetism in stars and star-planet systems” in September 2022.   Congratulations! Grace has started a job as a data scientist in the US, and Ekaterina will begin a postdoc position in my group on her…

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Cool Stars 21 conference in Toulouse ?>

Cool Stars 21 conference in Toulouse

This year the Cool Stars conference – the most important conference for the stellar half of my group’s research – took place in person again, for the first time since the pandemic started. Toulouse hosted the meeting this year, and it was a really good conference, lots of new scientific insights. A pretty big delegation from my group attended: PhD students Laura Ketzer, Ekaterina Ilin, Nikoleta Ilic, Judy Chebly, and guest student Yu Xu; postdocs Eliana Amazo-Gomez and Julián Alvarado-Gomez;…

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PETS paper II: Thermal Inversion Agents in KELT-20 b/MASCARA-2 b ?>

PETS paper II: Thermal Inversion Agents in KELT-20 b/MASCARA-2 b

The second paper of the PEPSI Exoplanet Transit Survey (PETS) performs a search for possible atomic and molecular species that may drive the thermal inversion in the atmospheres of ultrahot Jupiters, and it rules out several species in the case of KELT-20 b/MASCARA-2 b: Title: “The PEPSI-LBT Exoplanet Transit Survey (PETS). II. A Deep Search for Thermal Inversion Agents in KELT-20 b/MASCARA-2 b with Emission and Transmission Spectroscopy” Johnson, Marshall C.; Wang, Ji; Pai Asnodkar, Anusha; Bonomo, Aldo S.; Gaudi,…

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Paper on AU Mic and planet-triggered flares ?>

Paper on AU Mic and planet-triggered flares

One possible manifestation of (magnetic) star-planet interactions is flare triggering by a planet passing by some active region of the star and disturbing the magnetic field structure of the active region enough that a flare is triggered earlier than it usually would have occurred. My PhD student Ekaterina Ilin recently studied the many TESS-observed flares of the young planet-hosting star AU Mic to test whether there is any significant correlation of flare timing with the orbit of the exoplanet or…

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New and old group members ?>

New and old group members

We have a few new students in the group this spring (welcome to all of you!): – Julia Schötzig, a bachelor student from TH Wildau, working on exoplanet orbital obliquities from PEPSI data (mentored by Dr. Engin Keles) – Desmond Dsouza, a master student from Potsdam University, working on X-ray activity of wide binary stars (mentored by Nikoleta Ilic) – Joana Wokittel, a master student from Humboldt University, working on telluric corrections for exoplanet transmission spectra (working directly with me)…

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ELT instrumentation: the ANDES-UBV spectrograph a AIP ?>

ELT instrumentation: the ANDES-UBV spectrograph a AIP

The AIP is part of the ANDES consortium, with ANDES being the planned high-resolution, wide wavelength coverage spectrograph for the Extremely Large Telescope (ELT). The AIP is in charge of developing and building the UBV spectrograph of ANDES, and I am leading the UBV development as the PI. The whole ANDES spectrograph will have at least three individual spectrographs, one covering the UBV bands, one covering RIZ, and one covering YJH. An additional K-band spectrogrpah is still under discussion. ANDES…

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