Sylvana Yelda (UCLA) Title: Insight into Star Formation at the Galactic Center from Kinematics of the Young Stellar Disk

Abstract: The Galactic center (GC) contains both a supermassive black hole (SMBH) and a collection of young, massive stars, a seemingly paradoxical combination given our current knowledge of star formation. Approximately half of these young stars orbit the black hole in a coherent, clockwise stellar disk. The dynamics of this young population can be used to constrain theories of star formation in the hostile environment of a SMBH. I will present high-precision astrometry (~0.1 mas) of ~120 young stars obtained with the Keck telescopes over 16 years, including seven years of Laser Guide Star Adaptive Optics imaging and spectroscopy. Accelerations in the plane of the sky are detected as far out as 1.5" (~0.06 pc), the furthest from the SMBH to date for these young stars. Such measurements allow us to study the structure of the stellar disk and directly estimate stellar orbital parameters, including eccentricities, without making a priori assumptions about disk membership, as has been done in the past. Furthermore, seven disk stars have eccentricities > 0.2, while many others have eccentricity lower limits of 0.2. This finding renders in situ star formation in a circular disk with a normal IMF around the SMBH unlikely.