Identifying the Ejected Population from Disintegrating Multiple Systems
Alexandra Ka Po, Yip
Kinematic studies of the Hipparcos catalogue have revealed associations that are best explained as disintegrating multiple systems, presumably resulting from a dynamical encounter between single/multiple systems in the field (Li et al. 2009). In this project I have searched for disintegrating multiple systems in three database/catalogues; Dwarf Archive, the Hipparcos Main Catalogue, and the Gliese-Jahreiß Catalogue. My techniques were able to identify systems containing stars, as well as star/brown dwarf components. Distance constraints from parallax and spectrophotometry allowed me to identify common distance associations. Proper motion measurements allowed me to separate common proper motion multiples from my sample of disintegrating candidates. And proper motion and positional information allowed me to select candidate systems based on relative component positions that were tracked back and projected forward through time. Four candidate disintegrating multiple systems have been identified, all quadrupoles. One of these four systems contains a UCD (GJ 570 D). Another consists mainly of known members of the open cluster IC 2602, and the other two systems consist of M-K dwarfs and K dwarfs respectively. In addition I have identified two candidate disintegrating double systems, each containing one UCD component. The first one consists of a T1 dwarf and a white dwarf. The second one (the eta CrB system) has been previously identified as a bound multiple system, though my analysis suggested it could be disintegrating. In addition I have identified three multiples (previously unreported or with un-reported components) with component spectral types of; K1+K5 (spectroscopic binary), M0+M2 and M1+M3.5+M4. I discussed the properties of all these systems as well as the sample overall, considering sources of uncertainty and contamination, and discussed future work on the sample and to expand this area of research.