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Category: research

Paper on the atmospheric evaporation of four very young exoplanets ?>

Paper on the atmospheric evaporation of four very young exoplanets

Together with my PhD student Laura Ketzer and postdoc Matthias Mallonn, we have published a new paper on the atmospheric evaporation of the four very young planets around the star V1298 Tau. We measured the star’s X-ray spectrum by combining ROSAT and Chandra observations, and found that the star is highly active with an X-ray luminosity above 10^30 erg/s. Laura developed a numerical code to estimate the planetary evaporation as the star ages and becomes less X-ray bright. Depending on…

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Paper on the magnetic activity of old sunlike stars ?>

Paper on the magnetic activity of old sunlike stars

My freshly graduated PhD student, Dr. Rachel Booth, has published the final paper from her PhD thesis together with me and a few coworkers. We have analysed how the magnetic activity of sun-like stars decays as they age, and have used a sample of stars that all have well-determined asteroseismic ages. We find that even at old stellar ages on the main sequence the spin down and therefore the decay of stellar activity continues. For a read go here: “Chromospheric…

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Paper on alkali metals in an exoplanet’s atmosphere ?>

Paper on alkali metals in an exoplanet’s atmosphere

Together with my colleagues at AIP, and led by Engin Keles, a PhD student in my Star-Planet Systems group, we have published a paper on the detection of potassium in the atmosphere of a Hot Jupiter using high-resolution transmission spectroscopy. The potassium absorption on HD189733b and HD209458b, Keles, E.; Mallonn, M.; von Essen, C.; Carroll, T. A.; Alexoudi, X.; Pino, L.; Ilyin, I.; Poppenhäger, K.; Kitzmann, D.; Nascimbeni, V.; Turner, J. D.; Strassmeier, K. G. The Large Binocular Telescope (LBT)…

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White paper on X-ray interferometry ?>

White paper on X-ray interferometry

Together with many colleagues, I have contributed to a White Paper on a possible X-ray Interferometry mission. This project is led by Phil Uttley from the University of Amsterdam, and we hope to be considered for ESA’s Vision 2050 mission slot. X-ray interferometry can yield amazing spatial resolution for bright X-ray sources, even though there is still quite some technology to be developed. For stars and exoplanets, we could spatially resolve transits in front of the stellar corona – see…

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Exostar19 research program in Santa Barbara ?>

Exostar19 research program in Santa Barbara

This summer I organized a 3-month research program called Exostar19 (https://www.kitp.ucsb.edu/activities/exostar19) at the Kavli Institute for Theoretical Physics (KITP) in Santa Barbara, together with Bekki Dawson, Dan Huber, and Jim Fuller. Victor Silva Aguirre was the one who brought us all together with his idea to come up with a program that focuses on all the new insights that the stellar and planetary field can gain from TESS and Gaia data. It’s now the last week of the program, and…

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New paper: a small planet in the temperate zone of K2-133 ?>

New paper: a small planet in the temperate zone of K2-133

A new paper by my PhD student Rob Wells is now accepted for publication: “Validation of a temperate fourth planet in the K2-133 multiplanet system“, Wells, R.; Poppenhaeger, K.; Watson, C. A. Abstract: We present follow-up observations of the K2-133 multiplanet system. Previously, we announced that K2-133 contained three super-Earths orbiting an M1.5V host star – with tentative evidence of a fourth outer-planet orbiting at the edge of the temperate zone. Here, we report on the validation of the presence…

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Review on star-planet systems ?>

Review on star-planet systems

My review talk on interactions in star-planet systems I gave at the XMM-Newton science workshop in summer 2018 is now published in a peer-reviewed article: “How stars and planets interact: A look through the high-energy window“, Poppenhaeger, Katja Abstract: The architecture of exoplanetary systems is often different from the solar system, with some exoplanets being in close orbits around their host stars and having orbital periods of only a few days. In analogy to interactions between stars in close binary…

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New papers: exoplanets and stellar results from NGTS ?>

New papers: exoplanets and stellar results from NGTS

The Next Generation Transit Survey has had some new discoveries over the past few months which I was happy to contribute to. We’ve discovered a new exoplanet (an inflated hot Jupiter), a fully-convective eclipsing binary system, and a giant flare with pulsations on a pre-main sequence M star. The papers are: “NGTS-2b: an inflated hot-Jupiter transiting a bright F-dwarf”, L. Raynard and 44 co-authors including K. Poppenhaeger, Monthly Notices of the Royal Astronomical Society, Volume 481, Issue 4, p.4960-4970 (2018)…

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Home colloquium at AIP ?>

Home colloquium at AIP

Today I gave the colloquium talk at my new home institution, the AIP. I chose a quite relatable title with “A field trip to the exoplanet zoo”, and I was blown away by how many people showed up. We actually had to open the second half of the lecture hall, which is usually only done for conferences – quite flattering! It was good fun and my colleagues from the AIP and the university had a bunch of interesting questions. Looking…

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Invited colloquium at API Amsterdam ?>

Invited colloquium at API Amsterdam

Last week I was a guest at the Anton Pannekoek Intitute at the University of Amsterdam for two days and gave an invited colloquium. Also learned a lot about the research going on at Amsterdam, especially in the exoplanet groups of Birkby and Desert. Title and abstract of my talk: Strange beasts in the exoplanet zoo Almost all exoplanets known today are orbiting around cool stars. This is caused by certain biases in our planet detection methods, but nevertheless it…

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