2007A&A...476..217C


C.D.S. - SIMBAD4 rel 1.7 - 2020.03.28CET10:38:08

2007A&A...476..217C - Astronomy and Astrophysics, volume 476, 217-227 (2007/12-2)

Old open clusters in the outer Galactic disk.

CARRARO G., GEISLER D., VILLANOVA S., FRINCHABOY P.M. and MAJEWSKI S.R.

Abstract (from CDS):

The outer parts of the Milky Way disk are believed to be one of the main arenas where the accretion of external material in the form of dwarf galaxies and subsequent formation of streams is taking place. The Monoceros stream and the Canis Major and Argo over-densities are notorious examples. Understanding whether what we detect is the signature of accretion or, more conservatively, simply the intrinsic nature of the disk, represents one of the major goals of modern Galactic astronomy. We try to shed more light on the properties of the outer disk by exploring the properties of distant anti-center old open clusters. We want to verify whether distant clusters follow the chemical and dynamical behavior of the solar vicinity disk, or whether their properties can be better explained in terms of an extra-galactic population. VLT high resolution spectra have been acquired for five distant open clusters: Ruprecht 4, Ruprecht 7, Berkeley 25, Berkeley 73 and Berkeley 75. We derive accurate radial velocities to distinguish field interlopers and cluster members. For the latter we perform a detailed abundance analysis and derive the iron abundance [Fe/H] and the abundance ratios of several α elements. Our analysis confirms previous indications that the radial abundance gradient in the outer Galactic disk does not follow the expectations extrapolated from the solar vicinity, but exhibits a shallower slope. By combining the metallicity of the five program clusters with eight more clusters for which high resolution spectroscopy is available, we find that the mean metallicity in the outer disk between 12 and 21kpc from the Galactic center is [Fe/H]≃-0.35, with only marginal indications for a radial variation. In addition, all the program clusters exhibit solar scaled or slightly enhanced α elements, similar to open clusters in the solar vicinity and thin disk stars. We investigate whether this outer disk cluster sample might belong to an extra-galactic population, like the Monoceros ring. However, close scrutiny of their properties - location, kinematics and chemistry - does not convincingly favor this hypothesis. On the contrary, they appear more likely genuine Galactic disk clusters. We finally stress the importance to obtain proper motion measurements for these clusters to constrain their orbits.

Abstract Copyright:

Journal keyword(s): open clusters and associations: general - stars: fundamental parameters - Galaxy: disk - Galaxy: evolution - Galaxy: structure

VizieR on-line data: <Available at CDS (J/A+A/476/217): table2.dat table4.dat tab167.dat table5.dat>

Nomenclature: Table 2: Cl* Ruprecht 7 CGB N N=5 among (Nos 2-7), Cl* Ruprecht 4 CGB NN N=5 among (Nos 3-29).

Status at CDS:  

CDS comments: Table 2: the stars in Ruprecht clusters are not published in the ref. 2005MNRAS.360..655C.

Simbad objects: 46

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Number of rows : 46

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 188 OpC 00 48 26 +85 15.3           ~ 806 0
2 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2622 0
3 Cl Berkeley 17 OpC 05 20 37 +30 35.4           ~ 132 0
4 Cl Berkeley 20 OpC 05 32 37.0 +00 11 18           ~ 98 0
5 NAME Gal Anticenter reg 05 46 +28.9           ~ 706 0
6 Cl Berkeley 21 OpC 05 51 42 +21 47.0   12.26 11.1     ~ 90 0
7 Cl Berkeley 22 OpC 05 58.4 +07 50           ~ 63 0
8 NGC 2141 OpC 06 02 55 +10 26.8   10.43 9.4     ~ 115 0
9 Cl* Berkeley 73 CGM 12 * 06 21 54.9152865196 -06 17 51.801163490   16.30 15.30   13.93 ~ 3 0
10 Cl* Berkeley 73 CGM 13 * 06 21 55.3913626724 -06 20 09.830313564   16.10 15.36   14.30 ~ 3 0
11 Cl* Berkeley 73 CGM 19 * 06 21 57.2597559830 -06 17 15.267624561   16.74 16.03   14.95 ~ 3 0
12 Cl* Berkeley 73 CGM 16 * 06 22 01.130 -06 19 17.14   16.86 15.84   14.48 ~ 3 0
13 Cl* Berkeley 73 CGM 18 * 06 22 02.0057858614 -06 19 21.457206056   17.10 15.99   14.58 ~ 3 0
14 Cl Berkeley 73 OpC 06 22 06 -06 19.0           ~ 33 0
15 Cl* Berkeley 73 CGM 15 * 06 22 10.4374333954 -06 19 29.465909102   16.51 15.57   14.30 ~ 4 0
16 Cl* Berkeley 25 CGM 21 * 06 41 08.41007 -16 29 19.5000   17.59 16.50   15.08 ~ 2 0
17 Cl* Berkeley 25 CGM 13 * 06 41 13.6753193437 -16 29 16.479702192   17.36 16.33   14.97 ~ 5 0
18 Cl Berkeley 25 OpC 06 41 16 -16 29.2           ~ 44 0
19 Cl* Berkeley 25 CGM 12 * 06 41 16.6467940593 -16 28 15.400311118   17.59 16.32   14.78 ~ 4 0
20 Cl* Berkeley 25 CGM 23 * 06 41 16.760 -16 29 21.34   17.91 16.72   15.27 ~ 1 0
21 Cl* Berkeley 25 CGM 10 * 06 41 20.4491071730 -16 28 22.795937867   17.45 16.13   14.56 ~ 5 0
22 Cl* Ruprecht 4 CGB 3 * 06 48 51.6911406642 -10 30 20.534976415   15.46 14.24   12.69 ~ 3 0
23 Cl* Ruprecht 4 CGB 18 * 06 48 54.5815181544 -10 33 20.286110745   16.62 15.44   13.90 ~ 3 0
24 Cl* Ruprecht 4 CGB 8 * 06 48 55.44 -10 31 31.4   15.94 14.77   13.26 ~ 3 0
25 Cl* Berkeley 75 CGM 22 * 06 48 55.850 -24 00 07.16   17.08 16.13   14.99 ~ 3 0
26 C 0646-104 OpC 06 48 58 -10 30.6           ~ 29 0
27 Cl* Ruprecht 4 CGB 29 * 06 48 57.870 -10 30 27.09   17.29 15.95   14.25 ~ 3 0
28 Cl* Ruprecht 4 CGB 4 * 06 49 00.800 -10 31 57.81   15.60 14.30   12.68 ~ 3 0
29 Cl Berkeley 75 OpC 06 49 01.0 -23 59 48           ~ 40 0
30 Cl* Berkeley 75 CGM 9 * 06 49 07.1018654835 -23 59 44.989933406   15.78 14.89   13.71 ~ 3 0
31 Cl Berkeley 29 OpC 06 53 04.2 +16 55 39   14.3       ~ 137 0
32 Cl Berkeley 31 OpC 06 57 36 +08 16.0           ~ 94 0
33 Cl Berkeley 33 OpC 06 57 42 -13 13.0           ~ 61 0
34 2MASS J06574308-1312176 RG* 06 57 43.0853855154 -13 12 17.658653768   16.02 14.58   12.71 ~ 5 0
35 Cl* Ruprecht 7 CGB 2 * 06 57 50.1562702805 -13 13 40.225098643   15.47 14.07   12.71 ~ 4 0
36 Cl* Ruprecht 7 CGB 7 * 06 57 52.8617796149 -13 12 54.961683009   16.41 15.07   12.25 ~ 4 0
37 Cl* Ruprecht 7 CGB 6 * 06 57 53.6350572737 -13 12 57.845353335   16.24 14.79   12.91 ~ 4 0
38 2MASS J06575454-1313587 RG* 06 57 54.5501153740 -13 13 58.732857869   16.17 14.78   12.95 ~ 6 0
39 C 0701-207 OpC 07 03 05.0 -20 49 00           ~ 106 0
40 NAME CMa Dwarf Galaxy G 07 12.6 -27 40     -0.1     ~ 186 1
41 NAME Saurer A Cluster OpC 07 20.9 +01 48           ~ 53 0
42 Cl Collinder 261 OpC 12 38 11.5 -68 22 01     10.7     ~ 154 0
43 NAME NGP reg 12 51 26.275 +27 07 41.70           ~ 1006 0
44 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11305 0
45 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1694 2
46 NAME Monoceros Stream St* ~ ~           ~ 308 0

    Equat.    Gal    SGal    Ecl

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2020.03.28-10:38:09

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