Journal
ASTROPHYSICAL JOURNAL
Volume 838, Issue 1, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/aa5be7
Keywords
dark matter; galaxies: dwarf; galaxies: individual (Tucana III); galaxies: stellar content; Local Group; stars: abundances
Categories
Funding
- National Science Foundation [AST-1108811, 1138766]
- European Research Council [ERC-StG335936]
- U.S. Department of Energy
- U.S. National Science Foundation
- Ministry of Science and Education of Spain
- Science and Technology Facilities Council of the United Kingdom
- Higher Education Funding Council for England
- National Center for Supercomputing Applications at the University of Illinois at Urbana- Champaign
- Kavli Institute of Cosmological Physics at the University of Chicago
- Financiadora de Estudos e Projetos
- Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro
- Conselho Nacional de Desenvolvimento Cientifico e Tecnologico
- Ministerio da Ciencia e Tecnologia
- Deutsche Forschungsgemeinschaft
- Collaborating Institutions in the Dark Energy Survey
- MINECO [AYA2012-39559, ESP2013-48274, FPA2013-47986]
- Centro de Excelencia Severo Ochoa [SEV-2012-0234]
- European Union
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1138766] Funding Source: National Science Foundation
- Division Of Physics
- Direct For Mathematical & Physical Scien [1522717, 1125897] Funding Source: National Science Foundation
- ICREA Funding Source: Custom
- STFC [ST/P000525/1, ST/L006529/1, ST/I000976/1, ST/N001087/1, ST/L000652/1, ST/M003574/1, ST/H001581/1] Funding Source: UKRI
Ask authors/readers for more resources
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.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available