A high-velocity bulge rr lyrae variable on a halo-like orbit

Andrea Kunder, R. M. Rich, K. Hawkins, R. Poleski, J. Storm, C. I. Johnson, J. Shen, Z. Y. Li, M. J. Cordero, D. M. Nataf, G. Bono, A. R. Walker, A. Koch, R. De Propris, A. Udalski, M. K. Szymanski, I. Soszynski, G. Pietrzynski, K. Ulaczyk, L. WyrzykowskiP. Pietrukowicz, J. Skowron, S. Kozłowski, P. Mróz

    Research output: Contribution to journalArticlepeer-review

    24 Citations (Scopus)

    Abstract

    We report on the RR Lyrae variable star, MACHO 176.18833.411, located toward the Galactic bulge and observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay, which has the unusual radial velocity of -372 ± 8 km s-1 and true space velocity of -482 ± 22 km s-1 relative to the Galactic rest frame. Located less than 1 kpc from the Galactic center and toward a field at (l, b) = (3, -2.5), this pulsating star has properties suggesting it belongs to the bulge RR Lyrae star population, yet a velocity indicating it is abnormal, at least with respect to bulge giants and red clump stars. We show that this star is most likely a halo interloper and therefore suggest that halo contamination is not insignificant when studying metal-poor stars found within the bulge area, even for stars within 1 kpc of the Galactic center. We discuss the possibility that MACHO 176.18833.411 is on the extreme edge of the bulge RR Lyrae radial velocity distribution, and also consider a more exotic scenario in which it is a runaway star moving through the Galaxy.

    Original languageEnglish
    Article numberL12
    JournalAstrophysical Journal Letters
    Volume808
    Issue number1
    DOIs
    Publication statusPublished - 20 Jul 2015

    Fingerprint

    Dive into the research topics of 'A high-velocity bulge rr lyrae variable on a halo-like orbit'. Together they form a unique fingerprint.

    Cite this