RR Lyrae Stars in the Newly Discovered Ultra-faint Dwarf Galaxy Centaurus I*

被引：7

作者：

Martinez-Vazquez, C. E. ^{[1
]}

Cerny, W. ^{[2
,3
]}

Vivas, A. K. ^{[1
]}

Drlica-Wagner, A. ^{[2
,3
,4
]}

Pace, A. B. ^{[5
]}

Simon, J. D. ^{[6
]}

Munoz, R. R. ^{[7
]}

Walker, A. R. ^{[1
]}

Allam, S. ^{[4
]}

Tucker, D. L. ^{[4
]}

Adamow, M. ^{[8
]}

Carlin, J. L. ^{[9
]}

Choi, Y. ^{[10
]}

Ferguson, P. S. ^{[11
,12
]}

Ji, A. P. ^{[6
]}

Kuropatkin, N. ^{[4
]}

Li, T. S. ^{[6
,13
]}

Martinez-Delgado, D. ^{[14
]}

Mau, S. ^{[15
,16
]}

Mutlu-Pakdil, B. ^{[2
,3
]}

Nidever, D. L. ^{[17
,18
]}

Riley, A. H. ^{[11
,12
]}

Sakowska, J. D. ^{[19
]}

Sand, D. J. ^{[20
]}

Stringfellow, G. S. ^{[21
]}

机构：

[1] Cerro Tololo Interamer Observ, NSFs NOIRLab, Casilla 603, La Serena, Chile

[2] Univ Chicago, Kavli Inst Cosmol Phys, Chicago, IL 60637 USA

[3] Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA

[4] Fermilab Natl Accelerator Lab, POB 500, Batavia, IL 60510 USA

[5] Carnegie Mellon Univ, McWilliams Ctr Cosmol, 5000 Forbes Ave, Pittsburgh, PA 15213 USA

[6] Observ Carnegie Inst Sci, 813 Santa Barbara St, Pasadena, CA 91101 USA

[7] Univ Chile, Dept Astron, Camino Observ 1515, Santiago, Chile

[8] Natl Ctr Supercomp Applicat, Ctr Astrophys Surveys, 1205 West Clark St, Urbana, IL 61801 USA

[9] Rubin Observ Aura, 950 North Cherry Ave, Tucson, AZ 85719 USA

[10] Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA

[11] Texas A&M Univ, George P & Cynthia Woods Mitchell Inst Fundamenta, College Stn, TX 77843 USA

[12] Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 USA

[13] Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA

[14] CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain

[15] Stanford Univ, Dept Phys, 382 Via Pueblo Mall, Stanford, CA 94305 USA

[16] Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, POB 2450, Stanford, CA 94305 USA

[17] Montana State Univ, Dept Phys, POB 173840, Bozeman, MT 59717 USA

[18] NSFs Natl Opt Infrared Astron Res Lab, 950 N Cherry Ave, Tucson, AZ 85719 USA

[19] Univ Surrey, Dept Phys, Guildford GU2 7XH, Surrey, England

[20] Steward Observ, Dept Astron, 933 North Cherry Ave,Room N204, Tucson, AZ 85721 USA

[21] Univ Colorado, Ctr Astrophys & Space Astron, 389 UCB, Boulder, CO 80309 USA

来源：

ASTRONOMICAL JOURNAL | 2021年 / 162卷 / 06期

基金：

英国科学技术设施理事会; 美国国家科学基金会;

关键词：

LOCAL GROUP GALAXIES; VARIABLE-STARS; GLOBULAR-CLUSTER; INSIGHTS; HALO;

D O I：

10.3847/1538-3881/ac2368

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We report the detection of three RR Lyrae (RRL) stars (two RRc and one RRab) in the ultra-faint dwarf (UFD) galaxy Centaurus I (Cen I) and two Milky Way (MW) delta Scuti/SX Phoenicis stars based on multi-epoch giz DECam observations. The two RRc stars are located within two times the half-light radius (r ( h )) of Cen I, while the RRab star (CenI-V3) is at similar to 6 r ( h ). The presence of three distant RRL stars clustered this tightly in space represents a 4.7 sigma excess relative to the smooth distribution of RRL in the Galactic halo. Using the newly detected RRL stars, we obtain a distance modulus to Cen I of mu (0) = 20.354 +/- 0.002 mag (sigma = 0.03 mag), a heliocentric distance of D (circle dot) = 117.7 +/- 0.1 kpc (sigma = 1.6 kpc), with systematic errors of 0.07 mag and 4 kpc. The location of the Cen I RRL stars in the Bailey diagram is in agreement with other UFD galaxies (mainly Oosterhoff II). Finally, we study the relative rate of RRc+RRd (RRcd) stars (f (cd)) in UFD and classical dwarf galaxies. The full sample of MW dwarf galaxies gives a mean of f (cd) = 0.28. While several UFD galaxies, such as Cen I, present higher RRcd ratios, if we combine the RRL populations of all UFD galaxies, the RRcd ratio is similar to the one obtained for the classical dwarfs (f (cd) similar to 0.3). Therefore, there is no evidence for a different fraction of RRcd stars in UFD and classical dwarf galaxies.

引用

页数：10

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