Theia 456: Tidally Shredding an Open Cluster
Presenter: Kyle Tregoning
Title: Theia 456: Tidally Shredding an Open Cluster
Date/Time: Monday, June 17th, 2:30 - 4:00 PM; Thursday, June 20th, 3:30 - 5:00 PM
Abstract: The advent of machine learning and the application of clustering algorithms to the Gaia astrometric catalog has revolutionized our census of stellar structures in the Milky Way, particularly within the disk. Previously known stellar structures have been identified as having a common origin, and many new, disperse structures have been discovered. In this talk, I will discuss on one such structure, Theia 456, a loosely bound collection of roughly 350 stars spanning 120 pc. This structure has previously been shown to exhibit kinematic, chemical, and gryochronal coherency, indicating a common origin. Our collaboration obtained follow-up radial velocities and supplemented these with Gaia astrometry to provide a detailed description of Theia 456’s six dimensional phase space, allowing us to perform an in-depth dynamical analysis of the structure. By integrating stellar orbits through a Milky Way potential, we found that the currently dispersed structure coalesced into a small cluster in the past. Our model precisely predicts that Theia 456 formed 250 Myr ago, with a characteristic half mass radius of 8 pc and velocity dispersion of 0.15 km/s. Our results, which are entirely independent of model isochrones and details of stellar evolution, signify that Theia 456 is a unique benchmark for stellar population study.