PI: Andrea Kunder, Leibniz-Institut fuer Astrophysik, email@example.com
Address: Milky Way & The Local Volume, An Der Sternwarte 16, Potsdam 14482 Germany
CoI: R Michael Rich, UCLA
CoI: Jesper Storm, Leibniz-Institut fuer Astrophysik
CoI: Alistair Walker, CTIO
CoI: Christian I Johnson, Harvard-Smithsonian Center for Astrophysics
CoI: Giuseppe Bono, INAF, Rome Astronomical Observatory
CoI: David Nataf, Australian National U.
CoI: R de Propris, Finnish Centre for Astronomy with ESO (FINCA)
Title: The hidden bulge of the Milky Way: Spectroscopic follow-up of RR Lyrae Stars
Abstract: RR Lyrae stars are representatives of an old, metal-poor stellar population in the bulge. A pilot program has revealed that their kinematics are distinct from those of the more metal-rich bulge giants and trace a slow (or non-) rotating component that may be identified as the old classical spheroid of the Milky Way. However, our current observations are limited to the innermost 500 pc. This is where a slow- rotating component has the smallest velocity difference compared to the metal-rich bulge giants ($sim km~s$^$), and hence where population contamination from e.g., the halo or thick disk could more easily mask the effects of rotation. Further, because our observations are confined to the innermost longitudes, the extent of the old, non- rotating component is unknown. We therefore propose to extend our observations to greater longitudes using AAOmega. We propose to obtain spectra of $sim0 RR Lyrae stars at $l$$sim$$-.5 and at $l$$sim$+6.5, where a slow-rotating component has a velocity difference of $sim km~s$^$ compared to the bar/bulge, allowing for an unambiguous detection of a kinematically distinct population residing in the Milky Way bulge. Both confirming the null rotation of the RR Lyrae population, and expanding the possible area in which an old, classical spheroid resides is of vital importance to constrain bulge formation scenarios.
Program Type: Standard/Galactic
Run 1 (2016B): AAT/AAOmega -- 2n on Aug 09 - Aug 10 2016
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360