2009A&A...499..121F

Query : 2009A&A...499..121F

2009A&A...499..121F - Astronomy and Astrophysics, volume 499121-128 (2009/5-3)

Life at the periphery of the local group: the kinematics of the Tucana dwarf galaxy.

FRATERNALI F., TOLSTOY E., IRWIN M.J. and COLE A.A.

Abstract (from CDS):

Dwarf spheroidal galaxies in the Local Group are usually located close to the Milky Way or M31. Currently, there are two clear exceptions to this rule, and the Tucana dwarf galaxy is the most distant at almost 1 Mpc from the Milky Way. Our aim is to learn more about the nature of Tucana by measuring its radial velocity and internal kinematics. Using the VLT/FORS2 spectrograph in multi-object mode we were able to measure the velocities of 23 individual red giant branch stars in and around Tucana using the CaII triplet absorption lines. From this sample 17 reliable members have been identified. We measured the systemic velocity and dispersion of Tucana to be vhel=+194.0±4.3km/s and σl.o.s.=15.8+4.1–3.1km/s, respectively. These measures are obtained after removing the signature of rotation using a linear gradient of 6.5xR/Rcore±2.9km/s which corresponds to a rotation of ≃16km/s at the reliable limit of our data. Our systemic velocity corresponds to a receding velocity from the barycentre of the Local Group of vLG=+73.3km/s. We also determined the mean metallicity of Tucana to be [Fe/H]=-1.95±0.15 with a dispersion of 0.32±0.06 dex. Our study firmly excludes any obvious association of Tucana with the HI emission in the vicinity and shows that Tucana is a genuine dwarf spheroidal with low metallicity stars, no gaseous ISM and no recent star formation. The present location and relatively high recession velocity are consistent with Tucana having been an isolated Local Group galaxy for the majority of its existence.

Abstract Copyright: ∼

Journal keyword(s): galaxies: individual: Tucana dwarf - galaxies: structure - galaxies: kinematics and dynamics - galaxies: stellar content

Nomenclature: Table 3: [FTI2009] NN (Nos 1-23).

Simbad objects: 59

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Number of rows : 59
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 MCG-03-01-015 G 00 01 57.9 -15 27 50   11.50 11.10 10.93   ~ 782 2
2 NAME Andromeda XVIII G 00 02 14.5 +45 05 20     16.0     ~ 129 0
3 ESO 349-31 AG? 00 08 13.1536 -34 34 47.836   15.54   14.99   ~ 156 3
4 NGC 55 rG 00 14 53.602 -39 11 47.86 8.54 8.58 7.87 7.84   ~ 828 2
5 NAME Cetus Dwarf Galaxy G 00 26 10.8 -11 03 14     13.2     ~ 257 0
6 NAME Magellanic Stream HVC 00 32 -30.0           ~ 1079 1
7 M 31 AGN 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 13622 1
8 NGC 247 LSB 00 47 08.554 -20 45 37.44 10.11 9.61 9.10 8.87   ~ 480 2
9 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 3588 2
10 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
11 NGC 300 GiG 00 54 53.4465638304 -37 41 03.168402396 8.83 8.69 8.13 7.46   ~ 1614 2
12 NAME Scl Group GrG 01 00 06 -33 44.2           ~ 526 0
13 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1498 4
14 IC 1613 GiC 01 04 48.4071 +02 07 10.185   10.42 10.01 9.77   ~ 1316 2
15 NAME Phoenix Dwarf Galaxy Sy1 01 51 06.3 -44 26 41   13.48 13.2 12.69   ~ 575 2
16 UGCA 34 GiG 02 36 35.4662282832 +59 39 17.507008584   17       ~ 198 2
17 UGCA 86 AG? 03 59 48.30 +67 08 18.6   14.2 14.2     ~ 110 0
18 NAME Camel Galaxy LSB 04 25 16.6 +72 48 24   14.85       ~ 59 0
19 NGC 1569 rG 04 30 49.186 +64 50 52.52 11.72 11.86 11.03     ~ 1297 3
20 NGC 1560 GiG 04 32 49.087 +71 52 59.20   12.1       ~ 264 0
21 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
22 Z 264-88 AG? 09 16 02.0195908968 +52 50 42.051257412   14.0 13.2     ~ 141 0
23 Z 153-10 G 09 59 26.46 +30 44 47.0 14.08 13.54 13.26 13.33   ~ 652 0
24 Z 36-12 H2G 10 00 00.8217342072 +05 20 09.533389560 12.77 12.25 11.89 11.71   ~ 569 0
25 NGC 3109 AG? 10 03 06.877 -26 09 34.46 11.10 10.42 10.04 9.91   ~ 825 2
26 NAME Antlia Dwarf Galaxy G 10 04 03.9 -27 20 01 16.73 15.69 15.17 15.00   ~ 221 1
27 MCG-01-26-030 H2G 10 11 00.5 -04 41 30 12.48 12.13 11.93 11.78   ~ 789 2
28 Z 71-87 H2G 12 58 40.1930636208 +14 13 00.739589628 15.24 15.16 14.98 14.81   ~ 475 0
29 NAME Sgr dIG G 19 29 59.0 -17 40 41   15.5 13.6     ~ 323 1
30 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1661 0
31 MCG-02-53-003 G 20 46 51.7 -12 50 54 15.75 15.18 14.83 14.46   ~ 470 1
32 M 15 GlC 21 29 58.33 +12 10 01.2           ~ 3274 0
33 IC 5152 rG 22 02 41.521 -51 17 47.20   11.03 10.9 10.19   ~ 273 1
34 [FTI2009] 21 RG* 22 41 19.1 -64 25 28     21.78   20.59 ~ 2 0
35 [FTI2009] 19 RG* 22 41 24.799 -64 24 52.20   24.12 22.59 21.78 21.0 ~ 3 0
36 [FTI2009] 20 RG* 22 41 31.380 -64 27 13.10   21.28 20.716 20.34 19.920 ~ 3 0
37 [BMG2009] Tucana V9 RG* 22 41 35.599 -64 24 40.90   23.840 22.44 21.66 20.98 ~ 4 0
38 [BMG2009] Tucana V13 RG* 22 41 36.6 -64 24 58   23.74 22.27 21.46 20.77 ~ 3 0
39 [FTI2009] 17 RG* 22 41 38.321 -64 24 08.20   23.74 22.41 21.67 21.03 ~ 3 0
40 [FTI2009] 8 RG* 22 41 40.870 -64 24 57.80   24.11 22.68 21.90 21.28 ~ 3 0
41 [FTI2009] 6 RG* 22 41 44.270 -64 24 30.00     22.37   21.01 ~ 3 0
42 [FTI2009] 2 RG* 22 41 47.270 -64 25 20.30   23.91 22.44 21.62 20.97 ~ 3 0
43 [FTI2009] 1 RG* 22 41 48.8 -64 25 20   23.65 22.48 21.80 21.26 ~ 2 0
44 NAME Tuc Galaxy G 22 41 49.6 -64 25 10   15.7 15.2     ~ 324 0
45 [FTI2009] 15 RG* 22 41 49.980 -64 23 41.50   23.29 22.22 21.51 20.96 ~ 3 0
46 [FTI2009] 3 RG* 22 41 51.5 -64 25 25   24.05 22.64 21.89 21.22 ~ 2 0
47 [FTI2009] 4 RG* 22 41 53.890 -64 25 05.90   23.76 22.39 21.56 20.87 ~ 3 0
48 [FTI2009] 9 RG* 22 41 55.2 -64 24 21   23.64 22.28 21.53 20.85 ~ 2 0
49 [FTI2009] 5 RG* 22 41 57.1 -64 25 02   23.92 22.73 21.79 21.19 ~ 2 0
50 [FTI2009] 7 RG* 22 41 58.140 -64 25 25.00   23.77 22.63 21.92 21.35 ~ 3 0
51 [FTI2009] 10 ** 22 41 59.069 -64 24 42.20   23.95 22.45 21.69 21.01 ~ 3 0
52 [FTI2009] 11 RG* 22 42 00.3 -64 24 44   23.85 22.73 22.07 21.49 ~ 2 0
53 [FTI2009] 14 RG* 22 42 01.781 -64 24 25.90   23.77 22.28 21.55 20.86 ~ 3 0
54 [FTI2009] 12 RG* 22 42 02.5 -64 25 16   23.62 22.31 21.43 20.83 ~ 2 0
55 [FTI2009] 16 RG* 22 42 03.281 -64 24 42.00   24.04 22.49 21.63 20.96 ~ 2 0
56 [FTI2009] 22 RG* 22 42 16.610 -64 23 00.60   23.69 22.39 21.42 20.62 ~ 3 0
57 [FTI2009] 23 RG* 22 42 17.750 -64 22 33.50   22.66 21.449 20.86 20.089 ~ 2 0
58 Z 431-72 G 23 28 35.2 +14 44 35 13.85 13.16 12.52     ~ 499 1
59 NAME Local Group GrG ~ ~           ~ 9325 0

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