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Author: ktj

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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Code published: AltaiPony ?>

Code published: AltaiPony

My PhD student Ekaterina Ilin investigates stellar flares in various space-based observations, and has developed a flare-finding code names AltaiPony already a while ago. We used this in several of her papers, for example for the flare census in open clusters (Ilin et al. 2019, Ilin et al. 2021) and the high latitude flares on M dwarfs (Ilin et al. 2021, blog post). After having it available on github already for a good while, Ekaterina has now also published her…

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New group members and completed Master’s theses ?>

New group members and completed Master’s theses

We have two new group members who joined us this fall: Prachi Rahate, who is a Master student and works with Dr. Eliana Amazo-Gomez on stellar rotation, and Dr. Andy Gallagher, who is a postdoc and works with Dr. Matthias Steffen on 3D NLTE stellar atmospheres. Welcome! We also had two students successfully complete their Master theses over the summer: Marzie Hosseini completed her thesis on “Transits in the young system PTFO 8-8695, is there a planet?”, as well as…

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Paper on polar flares on fast-rotating M dwarfs ?>

Paper on polar flares on fast-rotating M dwarfs

My PhD student Ekaterina Ilin has discovered a new method to localize flares on fast-rotating stars, using the rotational modulation of flares that last longer than the stellar rotation. With her new method she found that flares on fast-rotating M dwarfs occur close to the poles of the star, instead of neat to the equator like on our own Sun. This could be good news for exoplanets and their habitability, because particles expelled by the star during flares may miss…

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