Rights statement: This is an author-created, un-copyedited version of an article accepted for publication/published in Astrophysical Journal Letters. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.1088/2041-8205/808/1/L12
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - A high-velocity bulge RR Lyrae variable on a halo-like orbit
AU - Kunder, Andrea
AU - Rich, R. M.
AU - Hawkins, K.
AU - Poleski, R.
AU - Storm, J.
AU - Johnson, C. I.
AU - Shen, J
AU - Li, Z.-y.
AU - Cordero, M. J.
AU - Nataf, D. M.
AU - Bono, G.
AU - Walker, A. R.
AU - Koch, Andreas
AU - Propris, R. De
AU - Udalski, A.
AU - Szymanski, M. K.
AU - Soszynski, I.
AU - Pietrzynski, G.
AU - Ulaczyk, K.
AU - Wyrzykowski, L.
AU - Pietrukowicz, P.
AU - Skowron, J.
AU - Kozłowski, S.
AU - Mróz, P.
N1 - This is an author-created, un-copyedited version of an article accepted for publication/published in Astrophysical Journal Letters. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.1088/2041-8205/808/1/L12
PY - 2015/7/16
Y1 - 2015/7/16
N2 - 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.
AB - 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.
U2 - 10.1088/2041-8205/808/1/L12
DO - 10.1088/2041-8205/808/1/L12
M3 - Journal article
VL - 808
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 1
M1 - L12
ER -