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Author: ktj

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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First paper of the PEPSI Exoplanet Transit Survey (PETS) publication series ?>

First paper of the PEPSI Exoplanet Transit Survey (PETS) publication series

Our group is in a collaboration with other groups from Germany, Italy and the US to perform the PEPSI Exoplanet Transit Survey (PETS), which investigates exoplanet atmospheres in transmission and reflection observations. The first paper of the paper series is now published, and it’s an investigation of the nature of 55 Cnc e, a small rocky exoplanet, performed by my postdoc Engin Keles. The PEPSI exoplanet transit survey (PETS) I: investigating the presence of a silicate atmosphere on the super-earth…

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Paper on tidal star-planet interaction ?>

Paper on tidal star-planet interaction

One of the major research questions in my group has reached a milestone – my PhD student Nikoleta Ilic led an investigation of the magnetic activity of planet-hosting stars that are located in wide multiple system with one or more other stars. Such systems allow us to test for an overactivity of the planet host star due to star-planet interaction (SPI) by using the other star(s) in the system as a negative, same-age control. Nikoleta found a significant correlation of…

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Paper on AU Mic’s space weather ?>

Paper on AU Mic’s space weather

A new study by our Schwarzschild Fellow Dr. Julián Alvarado-Gomez shows that the space weather of AU Mic makes the survival of exoplanet atmospheres very challenging. Simulating the Space Weather in the AU Mic System: Stellar Winds and Extreme Coronal Mass Ejections Alvarado-Gómez, Julián D.; Cohen, Ofer; Drake, Jeremy J.; Fraschetti, Federico; Poppenhaeger, Katja; Garraffo, Cecilia; Chebly, Judy; Ilin, Ekaterina; Harbach, Laura; Kochukhov, Oleg Two close-in planets have been recently found around the M-dwarf flare star AU Microscopii (AU Mic)….

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Paper on solar H alpha emission ?>

Paper on solar H alpha emission

My group recently collaborated with the solar physics group and in particular Dr. Andrea Dierke for an investigation of solar H alpha emission. The paper is now published! Solar H alpha excess during Solar Cycle 24 from full-disk filtergrams of the Chromospheric Telescope Diercke, A.; Kuckein, C.; Cauley, P. W.; Poppenhäger, K.; Alvarado-Gómez, J. D.; Dineva, E.; Denker, C. The chromospheric H-alpha spectral line is a strong line in the spectrum of the Sun and other stars. In the stellar…

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Paper on helium transits of exoplanets ?>

Paper on helium transits of exoplanets

During the first Covid lockdown I started what I call my little pandemic project. But then all the real-life consequences of living through a worldwide pandemic set in, and it took until early this year to wrap up my project. It is finally done! And it is the first single-author paper I have ever written. Here’s some information on the paper: Helium absorption in exoplanet atmospheres is connected to stellar coronal abundances Poppenhaeger, K. Transit observations in the helium triplet…

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