Nearest Neighbor: The Low-mass Milky Way Satellite Tucana III

被引：78

作者：

Simon, J. D. ^{[1
]}

Li, T. S. ^{[2
,3
,4
]}

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

Bechtol, K. ^{[5
]}

Marshall, J. L. ^{[3
,4
]}

James, D. J. ^{[6
,7
]}

Wang, M. Y. ^{[3
,4
]}

Strigari, L. ^{[3
,4
]}

Balbinot, E. ^{[8
]}

Kuehn, K. ^{[9
]}

Walker, A. R. ^{[7
]}

Abbott, T. M. C. ^{[7
]}

Allam, S. ^{[2
]}

Annis, J. ^{[2
]}

Benoit-Levy, A. ^{[10
,11
,12
]}

Brooks, D. ^{[11
]}

Buckley-Geer, E. ^{[2
]}

Burke, D. L. ^{[13
,14
]}

Carnero Rosell, A. ^{[15
,16
]}

Kind, M. Carrasco ^{[17
,18
]}

Carretero, J. ^{[19
,20
]}

Cunha, C. E. ^{[13
]}

D'Andrea, C. B. ^{[21
,22
]}

da Costa, L. N. ^{[15
,16
]}

DePoy, D. L. ^{[3
,4
]}

Desai, S. ^{[23
]}

Doel, P. ^{[11
]}

Fernandez, E. ^{[20
]}

Flaugher, B. ^{[2
]}

Frieman, J. ^{[2
,24
]}

Garcia-Bellido, J. ^{[25
]}

Gaztanaga, E. ^{[19
]}

Goldstein, D. A. ^{[26
,27
]}

Gruen, D. ^{[13
,14
]}

Gutierrez, G. ^{[2
]}

Kuropatkin, N. ^{[2
]}

Maia, M. A. G. ^{[15
,16
]}

Martini, P. ^{[28
,29
]}

Menanteau, F. ^{[17
,18
]}

Miller, C. J. ^{[30
,31
]}

Miquel, R. ^{[20
,32
]}

Neilsen, E. ^{[2
]}

Nord, B. ^{[2
]}

Ogando, R. ^{[15
,16
]}

Plazas, A. A. ^{[33
]}

Romer, A. K. ^{[34
]}

Rykoff, E. S. ^{[13
,14
]}

Sanchez, E. ^{[25
]}

Santiago, B. ^{[15
,35
]}

Scarpine, V. ^{[2
]}

机构：

[1] Carnegie Observ, 813 Santa Barbara St, Pasadena, CA 91101 USA

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

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

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

[5] LSST, 933 North Cherry Ave, Tucson, AZ 85721 USA

[6] Univ Washington, Dept Astron, Box 351580, Seattle, WA 98195 USA

[7] Natl Opt Astron Observ, Cerro Tololo Interamer Observ, Casilla 603, La Serena, Chile

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

[9] Australian Astron Observ, N Ryde, NSW 2113, Australia

[10] CNRS, Inst Astrophys Paris, UMR 7095, F-75014 Paris, France

[11] UCL, Dept Phys & Astron, Gower St, London WC1E 6BT, England

[12] UPMC Univ Paris 06, Sorbonne Univ, Inst Astrophys Paris, F-75014 Paris, France

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

[14] SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

[15] Lab Interinst E Astron LIneA, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, RJ, Brazil

[16] Observ Nacl, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, RJ, Brazil

[17] Univ Illinois, Dept Astron, 1002 W Green St, Urbana, IL 61801 USA

[18] Natl Ctr Supercomp Applicat, 1205 West Clark St, Urbana, IL 61801 USA

[19] CSIC, Inst Ciencies Espai, IEEC, Campus UAB,Carrer Can Magrans S-N, E-08193 Barcelona, Spain

[20] Barcelona Inst Sci & Technol, IFAE, Campus UAB, E-08193 Bellaterra, Barcelona, Spain

[21] Univ Portsmouth, Inst Cosmol & Gravitat, Portsmouth 3FX UK, Hants, England

[22] Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England

[23] IIT Hyderabad, Dept Phys, Kandi 502285, Telangana, India

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

[25] Ctr Invest Energet Medioambientales & Tecnol CIEM, Madrid, Spain

[26] Univ Calif Berkeley, Dept Astron, 501 Campbell Hall, Berkeley, CA 94720 USA

[27] Lawrence Berkeley Natl Lab, 1 Cyclotron Rd, Berkeley, CA 94720 USA

[28] Ohio State Univ, Ctr Cosmol & Astroparticle Phys, Columbus, OH 43210 USA

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

[30] Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA

[31] Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA

[32] Inst Catalana Recerca & Estudis Avancats, E-08010 Barcelona, Spain

[33] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA

[34] Univ Sussex, Dept Phys & Astron, Pevensey Bldg, Brighton BN1 9QH, E Sussex, England

[35] Inst Fis, UFRGS, Caixa Postal 15051, BR-91501970 Porto Alegre, RS, Brazil

[36] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Av Estados 5001, BR-09210580 Santo Andre, SP, Brazil

[37] Oak Ridge Natl Lab, Comp Sci & Math Div, Oak Ridge, TN 37831 USA

来源：

ASTROPHYSICAL JOURNAL | 2017年 / 838卷 / 01期

基金：

欧洲研究理事会; 美国国家科学基金会; 英国科学技术设施理事会;

关键词：

dark matter; galaxies: dwarf; galaxies: individual (Tucana III); galaxies: stellar content; Local Group; stars: abundances; DWARF SPHEROIDAL GALAXIES; DARK-MATTER; STELLAR KINEMATICS; OUTER HALO; DRACO II; HYDRA II; SEGUE; FAINT; CLUSTER; STARS;

D O I：

10.3847/1538-4357/aa5be7

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite Tucana. III (Tuc III). We identify 26 member stars in Tuc. III from which we measure a mean radial velocity of v(hel) = - 102.3 +/- 0.4 (stat.) +/- 2.0. (sys.) km s(-1), a velocity dispersion of 0.1(0.7)(+0.7) km s(-1), and a mean metallicity of = -[Fe/H] = -2.42(-0.08)(+0.07). The upper limit on the velocity dispersion is sigma < 1.5 km s(-1) at 95.5% confidence, and the corresponding upper limit on the mass within the half-light radius of Tuc. III is 9.0. x. 10(4) M-circle dot. We cannot rule out mass-to-light ratios as large as 240. Me/Le for Tuc. III, but much lower mass-to-light ratios that would leave the system baryon-dominated are also allowed. We measure an upper limit on the metallicity spread of the stars in Tuc. III of 0.19. dex at 95.5% confidence. Tuc. III has a smaller metallicity dispersion and likely a smaller velocity dispersion than any known dwarf galaxy, but a larger size and lower surface brightness than any known globular cluster. Its metallicity is also much lower than those of the clusters with similar luminosity. We therefore tentatively suggest that Tuc. III is the tidally stripped remnant of a dark matter-dominated dwarf galaxy, but additional precise velocity and metallicity measurements will be necessary for a definitive classification. If Tuc. III is indeed a dwarf galaxy, it is one of the closest external galaxies to the Sun. Because of its proximity, the most luminous stars in Tuc. III are quite bright, including one star at V = 15.7 that is the brightest known member star of an ultra-faint satellite.

引用

页数：14

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