On the triple-star origin of the planetary nebula Sh 2-71

In a paper led by David Jones with Romano Corradi from La Palma we tried to come up with a theory to explain the peculiar shape (including new distant emission regions firstly presented here) and central stars of the planetary nebula. Our preferred models includes Lidov-Kozai cycles and triple star disruption due to ejection of the planetary nebula.

Paper now accepted to MNRAS:https://arxiv.org/abs/1908.04582v1

Kinematics of Mass Loss from L2

Dominika Hubova expanded her Bachelor thesis and took the deepest look so far at ballistic mass loss from L2, focusing on what happens if the matter stream is initiated with offset from L2 and with a velocity kick. Dominika characterized the parameter space and found some new stream trajectories. Interestingly, even if the stream is launched slower than corotation, there are still many initial positions near L2 that provide sufficient tidal torque to unbind the material.

Paper is now accepted to MNRAS: https://arxiv.org/abs/1908.02659v1

Periodic Variables in the APOGEE Survey

A paper characterizing periodic and aperiodic variability of APOGEE targets with ASAS-SN data was recently accepted to MNRAS. In this effort led by Michał Pawlak, we characterized almost 2000 periodic variable stars, all with existing multi-epoch high-resolution spectroscopy from APOGEE. We found that eclipsing binaries tend to favor lower metallicities, as was recently found on purely spectroscopic samples. We characterized the variability with damped random walk stochastic process. This is a starting point for future investigations combining high-res spectroscopy from surveys with time-domain photometric information. The paper is available on astro-ph.

Molly Peeples visit

Molly Peeples from Space Telescope Science Institute / Johns Hopkins visited us for a week as part of the Role models in physics program supported by the US Embassy in Prague. She gave a talk on
“Exploring the Universe with Space Telescopes and Supercomputers” and a second talk about “The Universe at Low Density: How Cosmic Gas Flows Build Galaxies”. She talked with students.