NOAO >   Observing Info >   Approved Programs >   2017A-0195

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Program Information for 2017A-0195


PI: Andrea Kunder, Leibiniz Institute for Astrophysics, akunder@aip.de
Address: Milky Way & Local Volume, An der Sternwarte 16, Potsdam 14482 Germany

CoI: R Michael Rich, UCLA
CoI: R de Propris, University of Turku
CoI: David Nataf, Johns Hopkins U.
CoI: Christian I Johnson, Harvard-Smithsonian Center for Astrophysics
CoI: Andreas Koch, Lancaster University
CoI: Giuseppe Bono, Universit{'a} di Roma 2
CoI: Alistair Walker, CTIO

Title: Before the Bar: Spectroscopic follow-up of bulge RR Lyrae stars

Abstract: RR Lyrae stars (RRLs) are representatives of old, metal-poor stellar populations. A pilot program has revealed that the bulge RRLs have kinematics 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 ($sim$ 25 km/s), and hence where population contamination from e.g., the halo or thick disk could more easily mask the effects of rotation. We propose to obtain spectra of $sim$ 800 RR Lyrae stars at $l sim -6.5^$ and at $l sim +6.5^$, where a slow-rotating component has a velocity difference of $sim 60$ km/s compared to the bar/bulge, allowing for an unambiguous detection of a kinematically distinct population residing in the Milky Way bulge and tracing the extent of this component.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2017A):  AAT/AAOmega -- 2n on Jun 16 - Jun 17 2017


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