2003A&A...405..867B


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.16CEST10:42:28

2003A&A...405..867B - Astronomy and Astrophysics, volume 405, 867-901 (2003/7-3)

The Andromeda project. I. Deep HST-WFPC2 V, I photometry of 16 fields toward the disk and the halo of the M 31 galaxy. Probing the stellar content and metallicity distribution.

BELLAZZINI M., CACCIARI C., FEDERICI L., FUSI PECCI F. and RICH M.

Abstract (from CDS):

We have obtained HST-WFPC2 F555W and F814W photometry for 16 fields in the vicinity of the luminous nearby spiral galaxy M 31, sampling the stellar content of the disk and the halo at different distances from the center, from ∼20 to ∼150arcmin (i.e. ∼4.5 to 35kpc), down to limiting V and I magnitudes of ∼27. The Color-Magnitude Diagrams (CMD) obtained for each field show the presence of complex stellar populations, including an intermediate age/young population and older populations with a wide range of metallicity. Those fields superposed on the disk of M 31 generally show a blue plume of stars which we identify with main sequence members. According to this interpretation, we find that the star formation rate over the last 0.5 Gyr has varied dramatically with location in the disk. The most evident feature of all the CMDs is a prominent Red Giant Branch (RGB) with a descending tip in the V band, characteristic of metallicity higher than 1/10 Solar. A red clump is clearly detected in all of the fields, and a weak blue horizontal branch is frequently present. The metallicity distributions, obtained by comparison of the RGB stars with globular cluster templates, all show a long, albeit scantly populated, metal-poor tail and a main component peaking at [Fe/H]~-0.6. The most noteworthy characteristic of the abundance distributions is their overall similarity in all the sampled fields, covering a wide range of environments and galactocentric distances. Nevertheless, a few interesting differences and trends emerge from the general uniformity of the metallicity distributions. For example, the median [Fe/H] shows a slight decrease with distance along the minor axis (Y) up to Y≃20', but the metallicity gradient completely disappears beyond this limit. Also, in some fields a very metal-rich ([Fe/H]≥-0.2) component is clearly present. Whereas the fraction of metal-poor stars seems to be approximately constant (within few percent) in all fields, the fraction of metal-rich and, especially, very-metal-rich stars varies with position and seems to be more prominent in those fields superposed on the disk and/or with the presence of streams or substructures, e.g. Ibata et al. (2001Natur.412...49I). This might indicate and possibly trace interaction effects with some companion, e.g. M 32.

Abstract Copyright:

Journal keyword(s): galaxies: individual: M 31 - galaxies: stellar content - galaxies: structure - stars: abundances - stars: Hertzprung-Russell (HR) and C-M diagrams - techniques: photometric

Simbad objects: 24

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Number of rows : 24

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3628 0
2 NAME Mayall II GlC 00 32 46.53 +39 34 40.5   14.564 13.807 13.208 12.684 ~ 374 1
3 RX J0036.3+4053 GlC 00 36 20.86 +40 53 37.1 17.190 17.033 16.35 15.787 15.40 ~ 55 0
4 BA 3-17 GlC 00 39 33.72 +40 31 14.7 16.338 16.209 15.362 14.803 14.39 ~ 78 0
5 Bol 6 GlC 00 40 26.4828316304 +41 27 26.653846594 16.940 16.490 15.74 14.970 14.52 ~ 82 0
6 Bol 12 GlC 00 40 32.4598109034 +41 21 44.200706344 15.990 15.860 15.17 14.620 14.14 ~ 75 0
7 Bol 338 GlC 00 40 58.871 +40 35 47.41 15.123 15.034 14.168 13.621 13.27 ~ 73 0
8 Bol 27 GlC 00 41 14.524 +40 55 51.19 16.669 16.486 15.642 15.104 14.55 ~ 63 0
9 Bol 343 GlC 00 41 43.1011408698 +40 12 22.414305198 17.230 17.080 16.69 15.910 15.42 ~ 69 0
10 Bol 45 GlC 00 41 43.11 +41 34 20.1 17.059 16.665 15.727 15.140 14.63 ~ 98 0
11 2MASS J00415300+4047096 GlC 00 41 53.008 +40 47 09.65 15.986 15.776 14.967 14.474 14.03 ~ 75 0
12 HD 3969 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11271 1
13 NAME Mayall IV GlC 00 43 17.85 +39 49 13.2 15.900 15.710 15.219 14.639 14.122 ~ 82 0
14 [JSD2015] AP 881 GlC 00 44 14.3252318610 +41 19 19.376228666 15.875 15.559 14.682 14.230 13.74 ~ 69 0
15 Bol 233 GlC 00 44 42.12 +41 43 54.5 16.552 16.404 15.615 15.144 14.593 ~ 48 0
16 Bol 384 GlC 00 46 21.9300523115 +40 16 59.647551658 17.370 16.743 15.752 15.260 14.564 ~ 62 0
17 BA 3-8 GlC 00 46 27.016 +42 01 52.75 16.554 16.355 15.541 14.997 14.435 ~ 86 0
18 NAME Mayall VI GlC 00 46 49.4915614188 +42 44 46.820540389 17.080 16.673 15.944 15.402 14.95 ~ 44 0
19 Bol 405 GlC 00 49 39.80 +41 35 29.8 16.220 15.930 15.195 14.656   ~ 61 0
20 M 5 GlC 15 18 33.22 +02 04 51.7   7.34 5.95     ~ 1811 0
21 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2042 0
22 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 1939 0
23 NGC 6528 GlC 18 04 49.61 -30 03 20.8   12.12 10.65     ~ 477 0
24 NGC 6553 GlC 18 09 15.68 -25 54 27.9   9.08       ~ 546 0

    Equat.    Gal    SGal    Ecl

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2021.04.16-10:42:28

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