Mon, August 24, 2020
Mon, July 20, 2020
We begin with an overview of the precision stellar astrophysics enabled by the confluence of Gaia parallaxes with large-scale photometric and spectroscopic surveys. We then give examples of the new understanding of local Galactic structure that this has enabled, including in particular the detailed history of canonical star-forming regions, and the discovery of "stellar strings" reflecting the local conditions of recent star formation. We conclude with the example of a newly discovered, young, triple star system including an eclipsing binary, that provides prima facie evidence supporting the new "stellar strings" paradigm.
Mon, June 29, 2020
When an isolated binary black hole merges in the field of a galaxy, its gravitational-wave story is complete. But when black holes merge in a dense star cluster, their merger products can remain in the cluster, where they continue to participate in dynamical encounters, form binaries, and potentially merge again. In this talk I will describe the production of repeated mergers in globular clusters, and how the rate of mergers depends on the initial properties (e.g. spin) of black holes formed from stars. I will show how these "second-generation" black holes differ from black holes formed from stellar collapse, and how Advanced LIGO and Virgo can already distinguish these unique astrophysical populations.