The pristine dwarf-galaxy survey - III. Revealing the nature of the Milky Way globular cluster Sagittarius II

被引：22
作者：
Longeard, Nicolas [1 ]
Martin, Nicolas [2 ,3 ]
Ibata, Rodrigo A. [2 ]
Starkenburg, Else [4 ,5 ]
Jablonka, Pascale [1 ,6 ]
Aguado, David S. [7 ]
Carlberg, Raymond G. [8 ]
Cote, Patrick [9 ]
Gonzalez Hernandez, Jonay, I [10 ,11 ]
Lucchesi, Romain [1 ]
Malhan, Khyati [12 ]
Navarro, Julio F. [13 ]
Sanchez-Janssen, Ruben [14 ]
Thomas, Guillaume F. [9 ]
Venn, Kim [12 ]
McConnachie, Alan W. [9 ]
机构：
[1] Ecole Polytech Fed Lausanne EPFL, Lab Astrophys, CH-1290 Observatoire, Versoix, Switzerland
[2] Univ Strasbourg, Observ Astron Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg, France
[3] Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany
[4] Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany
[5] Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands
[6] Univ PSL, Observ Paris, CNRS, GEPI, Pl Jules Janssen, F-92195 Meudon, France
[7] Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England
[8] Univ Toronto, Dept Astron & Astrophys, Toronto, ON M5S 3H4, Canada
[9] NRC Herzberg Astron & Astrophys, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada
[10] Inst Astrofis Canarias, Via Lactea, E-38205 Tenerife, Spain
[11] Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain
[12] Stockholm Univ, Oskar Klein Ctr Cosmoparticle Phys, Dept Phys, AlbaNova, SE-10691 Stockholm, Sweden
[13] Univ Victoria, 3800 Finnerty Rd, Victoria, BC V8P 5C2, Canada
[14] Royal Observ, STFC UK Astron Technol Ctr, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland
来源：
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2021年 / 503卷 / 02期
关键词：
Globular Clusters: individual: Sagittarius II; Local Group; DARK-MATTER; SPECTROSCOPIC SURVEY; CHEMICAL ABUNDANCES; TRIANGULUM II; STAR CLUSTER; METAL-POOR; DRACO II; SATELLITE; FAINT; CONSTRAINTS;
D O I：
10.1093/mnras/stab604
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
We present a new spectroscopic study of the faint Milky Way satellite Sagittarius II. Using multiobject spectroscopy from the Fibre Large Array Multi-Element Spectrograph, we supplement the data set of Longeard et al. with 47 newly observed stars, 19 of which are identified as members of the satellite. These additional member stars are used to put tighter constraints on the dynamics and the metallicity properties of the system. We find a low velocity dispersion of sigma(SgrII)(v) = 1.7 +/- 0.5 km s(-1), in agreement with the dispersion of Milky Way globular clusters of similar luminosity. We confirm the very metal-poor nature of the satellite ([Fe/H](spectro)(SgrII) = -2.23 +/- 0.07) and find that the metallicity dispersion of Sgr II is not resolved, reaching only 0.20 at the 95 per cent confidence limit. No star with a metallicity below -2.5 is confidently detected. Therefore, despite the unusually large size of the system (r(h) = 35.5(-1.2)(-1.4) pc), we conclude that Sgr II is an old and metal-poor globular cluster of the Milky Way.
引用
收藏
页码：2754 / 2762
页数：9
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