Ondřej Pejcha

The recent EAS meeting in Padova, Italy, was a good opportunity to discuss new scientific collaborations with people who would be otherwise difficult to meet at one place.

Camille Landri spent two weeks visiting Dr. Paul Ricker at University of Illinois Urbana-Champaign working on hydrodynamical simulations of common envelope evolution. The trip received support from a student grant of which Camille is a PI.

PhD student from Hamburg Observatory came to visit us in Prague for two weeks to work on common envelope hydrodynamics including planets.

Our group had a major participation in a conference held at University of Barcelona: one of the five review talks and numerous discussions with the participation of Camille Landri, Jakub Cehula, Anthony Kirilov, Damien Gagnier, and Ondřej Pejcha.

Our group participated in a conference that was conveniently located in Prague. We contributed to the program by talks of Camille Landri, Jakub Cehula, and Ondřej Pejcha.

New paper by PhD student Camille Landri looks at how we can get asymmetric outflows from red supergiants such as VY CMa and other similar objects. The idea is that a companion coming in on a grazing excentric orbit will unbind a small amount of gas from the red supergiant. This gas is subject to rapid radiative cooling and forms dust, which gets pushed away from the supergiant by its radiative pressure. Radiative cooling and dust driving are necessary to form outflows that are anisotropic in the sense that the ejection happens only in a fraction of a solid angle near the pericenter. After many grazing orbits, the ejections form an asymmetric structure with imprinted spiral-like pattern. The paper (accepted to MNRAS) discusses origin, final fate, and observational implications of this scenario.

I had a great time giving colloquium at the historical library of Hamburg Observatory, talking to many interesting people and enjoying serene grounds and historic telescopes. Thanks Diego Calderón Espinoza for hosting me!

Our PhD student Milan Pešta is spending April at Australian National University in the group of Prof. Yuan-Sen Ting and working on various applications of machine learning in time-domain astronomy.

Our PhD students were successful in obtaining student grants from the Grant Agency of the Charles University. Camille Landri (with Anthony Kirilov as a co-I) won with a project title The impact of binary evolution on common envelope evolution, and Jakub Cehula will work on Baryon ejection in magnetar giant flares: implications for r-process nucleosynthesis and fast radio bursts. Congratulations!

Last week three of our PhD students travelled to New York to a Workshop on stable mass transfer in binaries held at Center for Computational Astrophysics. Milan and Jakub gave contributed talks on contact binaries and a new mass transfer model.