RSAA Colloquia / Seminars / Feast-of-Facts: Monday, 30 October 2017, 11:00-12:00; Duffield Lecture Theatre

Simon Murphy

"An exciting haul of planetary, binary and triple systems from pulsation timing"

The orbital parameters of binary stars at intermediate periods (100-1000 d) are difficult to measure with conventional methods and are very incomplete. For the past couple of years I’ve been developing a method that uses stellar pulsations to determine the orbital parameters of binary stars, which is particularly suited to intermediate periods and can detect objects down to planetary masses. It has tripled the number of intermediate-mass stars with fully solved binary orbits. The detected companions include planets, brown dwarfs, and main sequence stars with masses between 0.1 and 2.5 Msun; over 20% are white dwarfs in blue straggler systems, and a few companions could be neutron stars or black holes. Some systems are clear triples, and many will become Type Ia supernovae and related phenomena. Statistically robust mass-ratio and eccentricity distributions will be presented, and I will explain what they tell us about binary star formation.