2013A&A...550A...7L


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST00:44:19

2013A&A...550A...7L - Astronomy and Astrophysics, volume 550A, 7-7 (2013/2-1)

Population gradients and photometric metallicities in early- and transition-type dwarf galaxies: clues from the Sculptor group.

LIANOU S., GREBEL E.K., DA COSTA G.S., REJKUBA M., JERJEN H. and KOCH A.

Abstract (from CDS):

We focus on the resolved stellar populations of one early-type and four transition-type dwarf galaxies in the Sculptor group, with the aim to examine the potential presence of population gradients and place constraints on their mean metallicities. We use deep Hubble Space Telescope images to construct color-magnitude diagrams, from which we select stellar populations that trace different evolutionary phases in order to constrain their range of ages and metallicities, as well as to examine their spatial distribution. In addition, we use the resolved stars in the red giant branch in order to derive photometric metallicities. All studied dwarfs contain intermediate-age stars with ages of ∼1Gyr and older as traced by the luminous asymptotic giant branch and red clump stars, while the transition-type dwarfs contain also stars younger than ∼1Gyr as traced by a young main sequence and vertical red clump stars. Moreover, the spatial distribution of the stars that trace different evolutionary phases shows a population gradient in all transition-type dwarfs. The derived error-weighted mean metallicities, assuming purely old stellar populations, range from -1.5dex for ESO294-G010 to -1.9dex for Scl-dE1, and should be considered as lower limits to their true metallicities. Assuming intermediate-age stellar populations to dominate the dwarfs, we derive upper limits for the metallicities that are 0.3 to 0.2dex higher than the metallicities derived assuming purely old populations. We discuss how photometric metallicity gradients are affected by the age-metallicity degeneracy, which prevents strong conclusions regarding their actual presence. Finally, the transition-type dwarfs lie beyond the virial radius of their closest bright galaxy, as also observed for the Local Group transition-type dwarfs. Scl-dE1 is the only dwarf spheroidal in our sample and is an outlier in a potential morphology-distance relation, similar as the two isolated dwarf spheroidals of the Local Group, Tucana, and Cetus.

Abstract Copyright:

Journal keyword(s): galaxies: dwarf - galaxies: evolution - galaxies: stellar content - galaxies: groups: individual: Sculptor group

VizieR on-line data: <Available at CDS (J/A+A/550/A7): table1.dat e540_030.dat e540_032.dat e294_010.dat e410_005.dat scl_de1.dat>

CDS comments: On line material non accessible au 11/04/2013, probablement pas pour Simbad AlineE 11/04/2013

Simbad objects: 26

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Number of rows : 26

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 55 GiG 00 14 53.602 -39 11 47.86 8.54 8.58 7.87 7.84   ~ 704 2
2 NGC 59 GiG 00 15 25.126 -21 26 39.68 14.01 13.21 12.59 12.31   ~ 83 0
3 ESO 410-5 LSB 00 15 31.45 -32 10 47.3   15.32 14.9 14.58   ~ 90 1
4 NAME Scl-dE1 GC1 GlC 00 23 52.69 -24 41 58.0           ~ 9 0
5 ESO 294-10 G 00 26 33.4 -41 51 22   15.76 15.3 14.97   ~ 94 2
6 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10902 1
7 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 2929 2
8 ESO 540-30 G 00 49 21.1 -18 04 34   16.45   15.33   ~ 69 1
9 ESO 540-32 LSB 00 50 24.5 -19 54 23 17.44 16.54 16.01 15.70   ~ 63 1
10 NAME Scl Group GrG 01 00 06 -33 44.2           ~ 462 0
11 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1116 4
12 NAME Pisces I G 01 03 56.6 +21 53 41   16.18 14.3     ~ 357 0
13 NAME Phoenix Dwarf Galaxy Sy1 01 51 06.3 -44 26 41   13.48 13.2 12.69   ~ 448 2
14 NAME Fornax Dwarf Spheroidal G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1473 1
15 ACO S 373 ClG 03 38 30 -35 27.3           ~ 1538 0
16 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14826 1
17 NAME Carina dSph G 06 41 36.7 -50 57 58   22.14 11.0 19.47   ~ 991 0
18 NAME Leo T dSph G 09 34 53.4 +17 03 05     15.1     ~ 306 0
19 NAME M 81-82 Group GrG 09 55 +69.1           ~ 634 0
20 NAME Leo Dwarf Irregular Galaxy G 09 59 26.46 +30 44 47.0 14.08 13.54 13.26 13.33   ~ 547 0
21 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 5824 0
22 NAME Cen A Group GrG 13 20 33.9 -44 58 51           ~ 230 0
23 NAME Centaurus A Sy2 13 25 27.61509104 -43 01 08.8056025   8.18 6.84 6.66   ~ 3995 3
24 NAME Aquarius Dwarf G 20 46 51.7 -12 50 54 15.75 15.18 14.83 14.46   ~ 394 1
25 NAME Peg Dwarf Irregular Galaxy G 23 28 35.2 +14 44 35 13.85 13.16 12.52     ~ 420 1
26 NAME Local Group GrG ~ ~           ~ 6970 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-00:44:19

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