Chemical Abundance Analysis of Three α-poor, Metal-poor Stars in the Ultrafaint Dwarf Galaxy Horologium I

被引：35

作者：

Nagasawa, D. Q. ^{[1
,2
]}

Marshall, J. L. ^{[1
,2
]}

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

Hansen, T. T. ^{[4
]}

Simon, J. D. ^{[4
]}

Bernstein, R. A. ^{[4
]}

Balbinot, E. ^{[5
]}

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

Pace, A. B. ^{[1
,2
]}

Strigari, L. E. ^{[1
,2
]}

Pellegrino, C. M. ^{[1
,2
]}

DePoy, D. L. ^{[1
,2
]}

Suntzeff, N. B. ^{[1
,2
]}

Bechtol, K. ^{[6
]}

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

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

Abdalla, F. B. ^{[8
,9
]}

Allam, S. ^{[3
]}

Annis, J. ^{[3
]}

Benoit-Levy, A. ^{[8
,10
,11
]}

Bertin, E. ^{[10
,11
]}

Brooks, D. ^{[8
]}

Carnero Rosell, A. ^{[12
]}

Kind, M. Carrasco ^{[13
,14
]}

Carretero, J. ^{[15
]}

Cunha, C. E. ^{[16
]}

D'Andrea, C. B. ^{[17
]}

da Costa, L. N. ^{[12
]}

Davis, C. ^{[16
]}

Desai, S. ^{[18
]}

Doel, P. ^{[8
]}

Eifler, T. F. ^{[19
,20
]}

Flaugher, B. ^{[3
]}

Fosalba, P. ^{[21
]}

Frieman, J. ^{[3
,22
]}

Garcia-Bellido, J. ^{[23
]}

Gaztanaga, E. ^{[21
]}

Gerdes, D. W. ^{[24
,25
]}

Gruen, D. ^{[16
,26
]}

Gruendl, R. A. ^{[13
,14
]}

Gschwend, J.

Gutierrez, G. ^{[3
]}

Hartley, W. G. ^{[8
,27
]}

Honscheid, K. ^{[28
,29
]}

James, D. J. ^{[30
]}

Jeltema, T. ^{[31
]}

Krause, E. ^{[16
]}

Kuehn, K. ^{[32
]}

Kuhlmann, S. ^{[33
]}

Kuropatkin, N. ^{[3
]}

机构：

[1] Texas A&M Univ, Mitchell Inst Fundamental Phys & Astron, College Stn, TX 77843 USA

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

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

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

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

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

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

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

[9] Rhodes Univ, Dept Phys & Elect, POB 94, ZA-6140 Grahamstown, South Africa

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

[11] Univ Paris 06, UPMC, Sorbonne Univ, Inst Astrophys Paris,UMR 7095, F-75014 Paris, France

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

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

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

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

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

[17] Univ Penn, Dept Phys & Astron, Philadelphia, PA 19104 USA

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

[19] CALTECH, Dept Phys, Pasadena, CA 91125 USA

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

[21] CSIC, IEEC, Inst Space Sci, Campus UAB,Carrer Can Magrans S-N, E-08193 Barcelona, Spain

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

[23] Univ Autonoma Madrid, CSIC, Inst Fis Teor UAM, E-28049 Madrid, Spain

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

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

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

[27] ETH, Dept Phys, Wolfgang Pauli Str 16, CH-8093 Zurich, Switzerland

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

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

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

[31] Santa Cruz Inst Particle Phys, Santa Cruz, CA 95064 USA

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

[33] Argonne Natl Lab, 9700 South Cass Ave, Lemont, IL 60439 USA

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

[35] CIEMAT, Madrid, Spain

[36] Univ Fed Rio Grande do Sul, Inst Fis, Caixa Postal 15051, BR-91501970 Porto Alegre, RS, Brazil

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

[38] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083859 Campinas, SP, Brazil

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

[40] Univ Portsmouth, Inst Cosmol & Gravitat, Portsmouth PO1 3FX, Hants, England

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

来源：

ASTROPHYSICAL JOURNAL | 2018年 / 852卷 / 02期

基金：

澳大利亚研究理事会; 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：

galaxies: abundances; galaxies: dwarf; stars: abundances; stars: chemically peculiar; LABORATORY TRANSITION-PROBABILITIES; R-PROCESS-RICH; HIGH-RESOLUTION SPECTROSCOPY; SPHEROIDAL GALAXY; OSCILLATOR-STRENGTHS; GALACTIC HALO; ECHELLE SPECTROGRAPH; DARK-MATTER; 1ST STARS; SUN;

D O I：

10.3847/1538-4357/aaa01d

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several alpha-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H]similar to -2.6 and are not alpha-enhanced ([alpha/Fe] similar to 0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility of a different mechanism for the enrichment of Hor I compared to other satellites. We discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.

引用

页数：16

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