Browsed by
Author: ktj

Musings on teaching ?>

Musings on teaching

I will teach some new lecture courses this fall, and therefore I think a short review of my teaching over the past two years is in order. I’ve taught the module “Computational modelling in physics” twice in a row now, it’s a lecture and computer lab course for the first-year physics students. For some students, it’s the first time they actually program something, while others already have quite some experience when they start university. I introduced the students to Python…

Read More Read More

New paper: Magnetic activity of old cool stars ?>

New paper: Magnetic activity of old cool stars

Happy to report that my PhD student Rachel Booth has successfully published her first paper! It’s a very interesting analysis of the magnetic activity of old cool stars, with a surprising find about the decline of activity at old stellar ages. Our paper has also been featured on the Astrobites blog: https://astrobites.org/2017/07/03/adventures-in-watchmaking-for-cool-stars/. Here’s the abstract of the paper: Stars with convective envelopes display magnetic activity, which decreases over time due to the magnetic braking of the star. This age-dependence of…

Read More Read More

Conference “Atmospheres of disks and planets” at castle Ringberg ?>

Conference “Atmospheres of disks and planets” at castle Ringberg

I just spent a really exciting week at castle Ringberg in south Germany, where the Max-Planck Institute for Astronomy held a conference on exoplanet formation and atmospheric composition. Lots of interesting discussions and new results. I was invited to give a talk on the topic of “Stellar activity and planet characterisation” – one of my favourite topics to talk about. My personal highlight of the conference was Yamila Miguel’s presentation about the latest results from the Juno mission: we finally…

Read More Read More

Today’s seminar: R Coronae Borealis stars ?>

Today’s seminar: R Coronae Borealis stars

Today Geoff Clayton from Louisiana State University gave a talk about R Coronae Borealis stars at our astrophysics seminar. These kinds of stars show erratic drops of several magnitudes in brightness over hundreds of years (R Coronae Borealis itself was discovered to be variable in 1795), and it’s still a somewhat open question what these things actually *are*. It’s not at all my field of study, but it was a really interesting talk and exactly the kind of talk I…

Read More Read More

New paper: Testing if Fomalhaut b is a neutron star ?>

New paper: Testing if Fomalhaut b is a neutron star

Happy to report that our paper has also been picked for presentation on the Astrobites blog: https://astrobites.org/2017/03/24/a-neutron-star-in-the-eye-of-sauron/. Here’s the abstract of the paper: Fomalhaut b is a directly imaged object in the debris disk of the star Fomalhaut. It has been hypothesized to be a planet, however there are issues with the observed colours of the object that do not fit planetary models. An alternative hypothesis is that the object is a neutron star in the near fore- or background…

Read More Read More

Personal: some travel cancellations. ?>

Personal: some travel cancellations.

Unfortunately I have to cancel several research trips and conferences this spring and summer. I’ve recently come down with pneumonia (quite unexpectedly! with hospital stay and all) and full recovery is expected to take several months. I had planned to go to the Radio Habitability Conference in California and The X-ray Universe in Rome, for both of which I’m on the scientific organizing committee, but I won’t be able to go to those. I’ll also have to cancel several invited…

Read More Read More

Public lecture on exoplanets ?>

Public lecture on exoplanets

I’m giving a public lecture “Exotic worlds: planets in other solar systems and what they might look like” in the lecture series of the Irish Astronomy Association (IAA) on March 1st 2017. The location is the Bell Lecture Theatre at Queen’s University Belfast, 7pm. There will be biscuits and tea afterwards. Here’s a synopsis of the talk from the IAA: Dr Poppenhaeger will talk about how astronomers discover planets in other solar systems, and show a few of the most…

Read More Read More

New paper on magnetic cycle simulation of Proxima Centauri ?>

New paper on magnetic cycle simulation of Proxima Centauri

The recent discovery of an Earth-like exoplanet around Proxima Centauri has shined a spot light on slowly rotating fully convective M-stars. When such stars rotate rapidly (period <20 days), they are known to generate very high levels of activity that is powered by a magnetic field much stronger than the solar magnetic field. Recent theoretical efforts are beginning to understand the dynamo process that generates such strong magnetic fields. However, the observational and theoretical landscape remains relatively uncharted for fully…

Read More Read More

New papers on the ARCUS mission ?>

New papers on the ARCUS mission

Arcus is a NASA/MIDEX mission under development in response to the anticipated 2016 call for proposals. It is a freeflying, soft X-ray grating spectrometer with the highest-ever spectral resolution in the 8-51 Å (0.24 – 1.55 keV) energy range. The Arcus bandpass includes the most sensitive tracers of diffuse million-degree gas: spectral lines from O VII and O VIII, H- and He-like lines of C, N, Ne and Mg, and unique density- and temperature-sensitive lines from Si and Fe ions….

Read More Read More

New paper on the disappearing disk of TYC 8241 2652 1 ?>

New paper on the disappearing disk of TYC 8241 2652 1

TYC 8241 2652 1 is a young star that showed a strong mid-infrared (mid-IR, 8-25 mu) excess in all observations before 2008 consistent with a dusty disk. Between 2008 and 2010 the mid-IR luminosity of this system dropped dramatically by at least a factor of 30 suggesting a loss of dust mass of an order of magnitude or more. We aim to constrain possible models including removal of disk material by stellar activity processes, the presence of a binary companion,…

Read More Read More