2020MNRAS.491..356L

Query : 2020MNRAS.491..356L

2020MNRAS.491..356L - Mon. Not. R. Astron. Soc., 491, 356-377 (2020/January-1)

The Pristine Dwarf-Galaxy survey - II. In-depth observational study of the faint Milky Way satellite Sagittarius II.

LONGEARD N., MARTIN N., STARKENBURG E., IBATA R.A., COLLINS M.L.M., LAEVENS B.P.M., MACKEY D., RICH R.M., AGUADO D.S., ARENTSEN A., JABLONKA P., GONZALEZ HERNANDEZ J.I., NAVARRO J.F. and SANCHEZ-JANSSEN R.

Abstract (from CDS):

We present an extensive study of the Sagittarius II (Sgr II) stellar system using MegaCam g and i photometry, narrow-band, metallicity-sensitive calcium H&K doublet photometry and Keck II/DEIMOS multiobject spectroscopy. We derive and refine the Sgr II structural and stellar properties inferred at the time of its discovery. The colour-magnitude diagram implies Sgr II is old (12.0 ± 0.5 Gyr) and metal poor. The CaHK photometry confirms the metal-poor nature of the satellite ([Fe/H] CaHK = -2.32 ± 0.04 dex) and suggests that Sgr II hosts more than one single stellar population (σ _[FeH]^CaHK = 0.11^{+0.05}_{-0.03} dex). Using the Ca infrared triplet measured from our highest signal-to-noise spectra, we confirm the metallicity and dispersion inferred from the Pristine photometric metallicities ([Fe/H]spectro = -2.23 ± 0.05 dex, σ _[Fe/H]^spectro = 0.10 ^{+0.06}_{-0.04} dex). The velocity dispersion of the system is found to be σ v = 2.7^{+1.3}_{-1.0} { km s^{-1}} after excluding two potential binary stars. Sgr II's metallicity and absolute magnitude (MV = -5.7 ± 0.1 mag) place the system on the luminosity-metallicity relation of the Milky Way dwarf galaxies despite its small size. The low but resolved metallicity and velocity dispersions paint the picture of a slightly dark-matter-dominated satellite (M/L = 23.0^{+32.8}_{-23.0} M☉ L^{-1}_{☉ }). Furthermore, using the Gaia Data Release 2, we constrain the orbit of the satellite and find an apocentre of 118.4 ^{+28.4}_{-23.7} { kpc} and a pericentre of 54.8 ^{+3.3}_{-6.1} { kpc}. The orbit of Sgr II is consistent with the trailing arm of the Sgr stream and indicates that it is possibly a satellite of the Sgr dSph that was tidally stripped from the dwarf's influence.

Abstract Copyright: © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): galaxies: dwarf - Local Group

VizieR on-line data: <Available at CDS (J/MNRAS/491/356): table2.dat table3.dat>

Simbad objects: 163

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Number of rows : 163
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 NAME Tuc IV G 00 02.9 -60 51           ~ 69 0
2 [LQS2016] DES J0034-4902 GlC 00 33 59.60 -49 02 19.8           ~ 16 0
3 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 12647 1
4 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1359 4
5 NAME Segue 2 G 02 19 16.0 +20 10 31     15.2     ~ 262 0
6 NAME Sagittarius Stream St* 02 22 +00.0           ~ 874 0
7 NAME Eri III G 02 22 45.480 -52 17 04.92           ~ 63 0
8 NAME Fornax Dwarf Spheroidal G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1743 1
9 NAME Hor I G 02 55 31.7 -54 07 08           ~ 141 0
10 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 7066 0
11 NAME Reticulum II G 03 35 42.1 -54 02 57           ~ 309 0
12 Cl Melotte 25 OpC 04 29 47.3 +16 56 53           ~ 3074 0
13 NAME SMASH 1 GlC 06 20 59.90 -80 23 44.7           ~ 13 0
14 NAME UMa II Galaxy G 08 51 30.0 +63 07 48     13.3     ~ 374 0
15 NAME Segue 1 G 10 07 03.2 +16 04 25     15.3     ~ 465 1
16 Z 64-73 G 10 08 28.12 +12 18 23.4   11.3 10.0     ~ 1208 1
17 NAME Sextans dSph G 10 13 02.9 -01 36 53   12 10.4     ~ 854 0
18 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 328 1
19 NAME Willman 1 G 10 49 21.0 +51 03 00     15.2     ~ 320 0
20 Z 126-111 G 11 13 28.13 +22 09 10.1   12.9 12.0     ~ 840 0
21 NAME Leo IV Dwarf Galaxy G 11 32 57.0 -00 32 00     15.1     ~ 383 1
22 NAME Crater Cluster GlC 11 36 16.20 -10 52 38.8           ~ 91 1
23 NAME Coma Dwarf Galaxy G 12 26 59.0 +23 54 15     14.1     ~ 452 1
24 NAME CVn II dSph G 12 57 09.6 +34 19 12     16.1     ~ 263 2
25 NAME Kim 3 Cl* 13 22 45.20 -30 36 03.6           ~ 17 0
26 NAME CVn I dSph G 13 28 03.5 +33 33 21     13.1     ~ 326 1
27 NAME Bootes II G 13 58 00.0 +12 51 00     15.4     ~ 241 0
28 NAME Bootes Dwarf Spheroidal Galaxy G 14 00 00.0 +14 30 00     12.8     ~ 437 0
29 NAME Munoz 1 Cl* 15 01 48.02 +66 58 07.3           ~ 24 0
30 NAME UMi Galaxy G 15 09 08.0 +67 13 21   13.60 10.6     ~ 1359 0
31 NAME Hercules Dwarf Galaxy G 16 31 02.0 +12 47 30     14.0     ~ 345 1
32 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 2116 0
33 NAME Dra dSph G 17 20 14.335 +57 55 16.39   12.40 10.6     ~ 1331 1
34 Cl Terzan 5 Cl* 17 48 05.00 -24 46 48.0           ~ 847 1
35 NAME Sgr II Window reg 18 12 -27.9           ~ 18 0
36 NAME SDG G 18 55 19.0 -30 32 43   4.5 3.6     ~ 2187 2
37 PSO J298.0250-22.0650 * 19 52 06.00068640 -22 03 54.1450800           ~ 1 0
38 PSO J298.0336-22.0999 * 19 52 08.07545040 -22 05 59.6423040           ~ 1 0
39 PSO J298.0362-22.0664 * 19 52 08.68888080 -22 03 59.1940080           ~ 1 0
40 PSO J298.0469-22.0912 Pe* 19 52 11.27952000 -22 05 28.3931160           ~ 1 0
41 PSO J298.0491-22.0330 Pe* 19 52 11.78884080 -22 01 58.9945440           ~ 1 0
42 PSO J298.0520-22.0724 * 19 52 12.49075920 -22 04 20.8594560           ~ 1 0
43 PSO J298.0549-22.0412 * 19 52 13.18235760 -22 02 28.6273680           ~ 1 0
44 PSO J298.0597-22.0524 * 19 52 14.32940400 -22 03 08.9084880           ~ 1 0
45 PSO J298.0615-22.0259 * 19 52 14.77489920 -22 01 33.2750280           ~ 1 0
46 PSO J298.0631-22.0584 * 19 52 15.15352560 -22 03 30.2816160           ~ 1 0
47 PSO J298.0668-22.0314 * 19 52 16.04910240 -22 01 53.0930640           ~ 1 0
48 PSO J298.0748-22.0841 * 19 52 17.96641920 -22 05 03.0879600           ~ 1 0
49 PSO J298.0766-22.0871 Pe* 19 52 18.40656720 -22 05 13.7847840           ~ 1 0
50 PSO J298.0787-22.0723 * 19 52 18.89402640 -22 04 20.4242160           ~ 1 0
51 PSO J298.0808-22.0441 Pe* 19 52 19.41266160 -22 02 39.0964920           ~ 1 0
52 PSO J298.0845-22.0470 * 19 52 20.30212560 -22 02 49.5174840           ~ 1 0
53 PSO J298.0868-22.1002 * 19 52 20.83650000 -22 06 00.8134560           ~ 1 0
54 PSO J298.0896-22.0293 * 19 52 21.51094320 -22 01 45.5736360           ~ 1 0
55 PSO J298.1019-22.0690 * 19 52 24.45949200 -22 04 08.4174960           ~ 1 0
56 PSO J298.1081-22.0721 * 19 52 25.95196800 -22 04 19.8873120           ~ 1 0
57 PSO J298.1137-22.0793 * 19 52 27.29706000 -22 04 45.6056040           ~ 1 0
58 PSO J298.1175-22.0770 * 19 52 28.22085840 -22 04 37.3516680           ~ 1 0
59 PSO J298.1251-22.0461 Pe* 19 52 30.03347760 -22 02 46.1956920           ~ 1 0
60 PSO J298.1276-22.1728 Pe* 19 52 30.63702720 -22 10 22.4297040           ~ 1 0
61 PSO J298.1288-22.1574 * 19 52 30.93506160 -22 09 26.6578920           ~ 1 0
62 PSO J298.1313-21.9827 * 19 52 31.53396000 -21 58 57.8224560           ~ 1 0
63 PSO J298.1315-21.9858 * 19 52 31.58002080 -21 59 08.9741760           ~ 1 0
64 PSO J298.1336-22.1037 * 19 52 32.06881680 -22 06 13.4918280           ~ 1 0
65 PSO J298.1366-21.9742 * 19 52 32.79968160 -21 58 27.2963640           ~ 1 0
66 PSO J298.1394-22.1762 * 19 52 33.47691840 -22 10 34.3657560           ~ 1 0
67 Pristine J298.1397-22.0253 * 19 52 33.54 -22 01 31.3           ~ 1 0
68 PSO J298.1409-22.0420 * 19 52 33.81954240 -22 02 31.2168840           ~ 1 0
69 PSO J298.1476-22.1898 * 19 52 35.43528960 -22 11 23.4286800           ~ 1 0
70 PSO J298.1482-22.0024 Pe* 19 52 35.57316480 -22 00 08.9006760           ~ 1 0
71 PSO J298.1489-22.0434 * 19 52 35.74110000 -22 02 36.5472960           ~ 1 0
72 PSO J298.1490-22.0235 * 19 52 35.76792720 -22 01 24.9409560           ~ 1 0
73 PSO J298.1494-22.1793 * 19 52 35.86357920 -22 10 45.7392000           ~ 1 0
74 PSO J298.1495-22.1070 * 19 52 35.89749120 -22 06 25.3725480           ~ 1 0
75 PSO J298.1500-22.0173 * 19 52 36.01826640 -22 01 02.6298120           ~ 1 0
76 PSO J298.1509-21.9528 * 19 52 36.23895840 -21 57 10.2312720           ~ 1 0
77 PSO J298.1510-22.0793 Pe* 19 52 36.2418921576 -22 04 45.783801876           ~ 2 0
78 PSO J298.1517-22.1492 * 19 52 36.40879440 -22 08 57.4626480           ~ 1 0
79 PSO J298.1524-22.0616 * 19 52 36.58566240 -22 03 41.9541480           ~ 1 0
80 PSO J298.1540-22.1110 * 19 52 36.97460160 -22 06 39.9434040           ~ 1 0
81 PSO J298.1543-22.0707 * 19 52 37.04636160 -22 04 14.7206280           ~ 1 0
82 PSO J298.1551-21.9805 * 19 52 37.22635680 -21 58 49.9248120           ~ 1 0
83 PSO J298.1556-22.0577 Pe* 19 52 37.34602800 -22 03 28.0228680           ~ 1 0
84 PSO J298.1585-22.0584 RR* 19 52 38.0510145336 -22 03 30.527101584           ~ 5 0
85 PSO J298.1612-22.0082 * 19 52 38.69589840 -22 00 29.7813960           ~ 1 0
86 PSO J298.1614-22.0826 Pe* 19 52 38.7509621928 -22 04 57.554654160           ~ 3 0
87 PSO J298.1618-22.0532 * 19 52 38.85496320 -22 03 11.5655400           ~ 1 0
88 PSO J298.1621-22.0544 Pe* 19 52 38.9281439880 -22 03 15.845887332           ~ 2 0
89 PSO J298.1623-22.0774 Pe* 19 52 38.97112320 -22 04 38.9347320           ~ 1 0
90 PSO J298.1630-22.0824 Pe* 19 52 39.1283978640 -22 04 56.774583840           ~ 2 0
91 PSO J298.1633-22.1432 * 19 52 39.20447280 -22 08 35.6602560           ~ 1 0
92 PSO J298.1638-22.1861 * 19 52 39.33028320 -22 11 10.2079320           ~ 1 0
93 PSO J298.1639-22.0634 Pe* 19 52 39.35937120 -22 03 48.5603640           ~ 1 0
94 PSO J298.1642-22.1680 Pe* 19 52 39.41800080 -22 10 04.9077840           ~ 1 0
95 PSO J298.1646-22.0916 * 19 52 39.50553120 -22 05 29.9971680           ~ 1 0
96 PSO J298.1664-22.0676 Pe* 19 52 39.94088160 -22 04 03.7124040           ~ 1 0
97 PSO J298.1681-22.1883 * 19 52 40.34938080 -22 11 17.8956960           ~ 1 0
98 NAME Sagittarius II Gl? 19 52 40.5 -22 04 05           ~ 74 0
99 PSO J298.1696-22.1746 * 19 52 40.71632400 -22 10 28.6790880           ~ 1 0
100 PSO J298.1717-22.1226 * 19 52 41.21337120 -22 07 21.5447520           ~ 1 0
101 PSO J298.1725-22.0741 * 19 52 41.4139201104 -22 04 26.810187564           ~ 2 0
102 PSO J298.1732-22.1158 * 19 52 41.56895760 -22 06 57.0783600           ~ 1 0
103 PSO J298.1748-22.1660 * 19 52 41.97092160 -22 09 57.8545200           ~ 1 0
104 PSO J298.1750-22.0542 * 19 52 42.00138240 -22 03 15.1545240           ~ 1 0
105 PSO J298.1768-22.0559 * 19 52 42.43340880 -22 03 21.3678720           ~ 1 0
106 PSO J298.1776-22.0460 WD? 19 52 42.6363435672 -22 02 45.667956084           ~ 2 0
107 PSO J298.1800-22.0717 * 19 52 43.20682800 -22 04 18.2910000           ~ 1 0
108 PSO J298.1811-22.0607 * 19 52 43.47117360 -22 03 38.7970920           ~ 1 0
109 PSO J298.1821-22.0570 * 19 52 43.71597120 -22 03 25.5353040           ~ 1 0
110 PSO J298.1822-22.0427 * 19 52 43.75180560 -22 02 33.9349920           ~ 1 0
111 PSO J298.1824-22.1056 * 19 52 43.78967760 -22 06 20.3497920           ~ 1 0
112 PSO J298.1832-21.9636 * 19 52 43.97645280 -21 57 49.0389120           ~ 1 0
113 PSO J298.1833-22.0702 Pe* 19 52 43.99994640 -22 04 12.8416800           ~ 1 0
114 PSO J298.1868-21.9771 Pe* 19 52 44.85573120 -21 58 37.6901760           ~ 1 0
115 Pristine J298.1891-22.0719 * 19 52 45.40 -22 04 18.9           ~ 1 0
116 PSO J298.1907-21.9675 Pe* 19 52 45.77541120 -21 58 03.3125160           ~ 1 0
117 PSO J298.1919-22.1968 * 19 52 46.06088880 -22 11 48.7408200           ~ 1 0
118 PSO J298.1930-22.0221 * 19 52 46.3265918688 -22 01 19.875292032           ~ 2 0
119 PSO J298.1940-22.0863 Pe* 19 52 46.57411200 -22 05 11.0285520           ~ 1 0
120 PSO J298.1943-21.9906 * 19 52 46.65096240 -21 59 26.5174800           ~ 1 0
121 PSO J298.1962-21.9936 * 19 52 47.08836240 -21 59 37.3072560           ~ 1 0
122 PSO J298.1963-22.1824 * 19 52 47.11500960 -22 10 56.8796880           ~ 1 0
123 PSO J298.1966-22.1463 * 19 52 47.19510240 -22 08 46.9142160           ~ 1 0
124 PSO J298.1970-22.0714 * 19 52 47.29522080 -22 04 17.3488080           ~ 1 0
125 PSO J298.1972-22.1245 * 19 52 47.34229200 -22 07 28.3271880           ~ 1 0
126 PSO J298.1983-22.1449 * 19 52 47.59773120 -22 08 41.9607960           ~ 1 0
127 PSO J298.1991-22.0846 * 19 52 47.78943360 -22 05 04.8145200           ~ 1 0
128 PSO J298.2007-22.0597 * 19 52 48.17158800 -22 03 35.0248320           ~ 1 0
129 PSO J298.2045-22.0537 * 19 52 49.08230400 -22 03 13.4242200           ~ 1 0
130 PSO J298.2052-22.0275 * 19 52 49.27019280 -22 01 39.0006840           ~ 1 0
131 PSO J298.2060-21.9878 * 19 52 49.44174480 -21 59 16.4175720           ~ 1 0
132 PSO J298.2085-22.0617 * 19 52 50.05663920 -22 03 42.2723160           ~ 1 0
133 PSO J298.2146-22.0934 * 19 52 51.5087147232 -22 05 36.223021248           ~ 2 0
134 PSO J298.2189-22.0719 Pe* 19 52 52.54043040 -22 04 19.0999200           ~ 1 0
135 PSO J298.2231-22.0397 * 19 52 53.54579760 -22 02 23.1204480           ~ 1 0
136 PSO J298.2387-22.1007 * 19 52 57.30095760 -22 06 02.6624880           ~ 1 0
137 PSO J298.2504-22.0809 * 19 53 00.11270640 -22 04 51.3019920           ~ 1 0
138 PSO J298.2547-22.0519 * 19 53 01.13776080 -22 03 06.8491800           ~ 1 0
139 PSO J298.2566-22.0404 * 19 53 01.58522400 -22 02 25.4499360           ~ 1 0
140 PSO J298.2611-22.0319 * 19 53 02.67067920 -22 01 55.1374320           ~ 1 0
141 PSO J298.2628-22.1019 * 19 53 03.07642800 -22 06 07.1296920           ~ 1 0
142 PSO J298.2670-22.0832 * 19 53 04.09325760 -22 04 59.7933840           ~ 1 0
143 PSO J298.2688-22.0281 * 19 53 04.51368720 -22 01 41.3618880           ~ 1 0
144 PSO J298.2707-22.0963 * 19 53 04.97453520 -22 05 47.0241600           ~ 1 0
145 PSO J298.2800-22.0767 * 19 53 07.20258960 -22 04 36.2353080           ~ 1 0
146 PSO J298.2816-22.0836 * 19 53 07.60238400 -22 05 01.2195960           ~ 1 0
147 PSO J298.2868-22.0417 * 19 53 08.85334560 -22 02 30.2107560           ~ 1 0
148 PSO J298.2893-22.0690 * 19 53 09.45066480 -22 04 08.5665360           ~ 1 0
149 PSO J298.2914-22.0752 Pe* 19 53 09.94804800 -22 04 30.8187840           ~ 1 0
150 PSO J298.2953-22.0759 * 19 53 10.88948880 -22 04 33.3436080           ~ 1 0
151 PSO J298.2977-22.1004 * 19 53 11.46786720 -22 06 01.7044200           ~ 1 0
152 PSO J298.3070-22.0904 * 19 53 13.69133280 -22 05 25.7562600           ~ 1 0
153 PSO J298.3119-22.0670 * 19 53 14.87264400 -22 04 01.3368720           ~ 1 0
154 PSO J298.3159-22.0679 Pe* 19 53 15.82518000 -22 04 04.5056640           ~ 1 0
155 NAME Indus I Cl* 21 08 49.970 -51 09 48.60           ~ 58 0
156 M 15 GlC 21 29 58.33 +12 10 01.2           ~ 3140 0
157 NAME Gru II G 22 04.1 -46 26           ~ 85 0
158 NAME Balbinot 1 Cl* 22 10 42.819 +14 56 49.03           ~ 27 0
159 NAME Kim 1 Cl* 22 11 41.30 +07 01 31.8           ~ 29 0
160 NAME Pegasus III G 22 24 22.6 +05 25 12           ~ 55 0
161 NAME Pisces II G 22 58 31.0 +05 57 09     16.3     ~ 258 0
162 NAME Tuc III G 23 56.6 -59 36           ~ 189 0
163 NAME Local Group GrG ~ ~           ~ 8390 0

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