A HIGH-VELOCITY BULGE RR LYRAE VARIABLE ON A HALO-LIKE ORBIT

被引：24

作者：

Kunder, Andrea ^{[1
]}

Rich, R. M. ^{[2
]}

Hawkins, K. ^{[3
]}

Poleski, R. ^{[4
,5
]}

Storm, J. ^{[1
]}

Johnson, C. I. ^{[6
]}

Shen, J. ^{[7
]}

Li, Z. -Y. ^{[7
]}

Cordero, M. J. ^{[8
]}

Nataf, D. M. ^{[9
]}

Bono, G. ^{[10
,11
]}

Walker, A. R. ^{[12
]}

Koch, A. ^{[13
]}

De Propris, R. ^{[14
]}

Udalski, A. ^{[5
]}

Szymanski, M. K. ^{[5
]}

Soszynski, I. ^{[5
]}

Pietrzynski, G. ^{[5
,15
]}

Ulaczyk, K. ^{[5
,16
]}

Wyrzykowski, L. ^{[5
]}

Pietrukowicz, P. ^{[5
]}

Skowron, J. ^{[5
]}

Kozlowski, S. ^{[5
]}

Mroz, P. ^{[5
]}

机构：

[1] Leibniz Inst Astrophys Potsdam AIP, D-14482 Potsdam, Germany

[2] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA

[3] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England

[4] Ohio State Univ, Dept Astron, Columbus, OH 43210 USA

[5] Univ Warsaw Observ, PL-00478 Warsaw, Poland

[6] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA

[7] Chinese Acad Sci, Shanghai Astron Observ, Key Lab Res Galaxies & Cosmol, Shanghai 200030, Peoples R China

[8] Zentrum Astron, Astron Rech Inst, D-69120 Heidelberg, Germany

[9] Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia

[10] Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy

[11] Rome Astron Observ, INAF, I-00040 Monte Porzio Catone, Italy

[12] Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, La Serena, Chile

[13] Heidelberg Univ, Zentrum Astron, Landessternwarte, D-69117 Heidelberg, Germany

[14] Univ Turku, Finnish Ctr Astron ESO FINCA, Turku, Finland

[15] Univ Concepcion, Dept Astron, Concepcion, Chile

[16] Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England

来源：

ASTROPHYSICAL JOURNAL LETTERS | 2015年 / 808卷 / 01期

基金：

中国国家自然科学基金; 美国国家科学基金会;

关键词：

Galaxy: bulge; Galaxy: formation; Galaxy: halo; Galaxy: kinematics and dynamics; stars: Population II; stars: variables: RR Lyrae; GALACTIC BULGE; LIGHT CURVES; OGLE-III; STARS; METALLICITY; EXTINCTION; MAGNITUDE; DISTANCE; GALAXY; MILKY;

D O I：

10.1088/2041-8205/808/1/L12

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

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.

引用

页数：6

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