2011MNRAS.413.1764P


C.D.S. - SIMBAD4 rel 1.7 - 2020.09.25CEST09:51:45

2011MNRAS.413.1764P - Mon. Not. R. Astron. Soc., 413, 1764-1776 (2011/May-3)

Nuclei of early-type dwarf galaxies: insights from stellar populations.

PAUDEL S., LISKER T. and KUNTSCHNER H.

Abstract (from CDS):

We present a comprehensive analysis of the spatially resolved stellar population properties of 26 early-type dwarf galaxies (dEs) in the Virgo cluster. Using Lick/IDS absorption line indices we derive simple stellar population (SSP) equivalent age, metallicity and [α/Fe] abundance ratio. In particular, we focus on the comparison of the stellar populations between the central nucleus and the surrounding galactic main body. The stellar populations of the nuclei are, for most dEs, significantly younger than those of the respective galactic main bodies, with an average difference of 3.5 Gyr. We find only five dEs with significantly older nuclei than their galactic main bodies. Furthermore, we observe most dE nuclei to be more metal rich compared to their host galaxies. These age and metallicity behaviours are shown by almost all dEs brighter than Mr=-17 mag.

The metallicity of both nuclei and galactic main bodies correlates with the total luminosity of the dEs. However, the metallicity of the nuclei covers a larger range (+0.18 to -1.22 dex) than that of the galactic main bodies, which all have subsolar metallicity. The ages of dE nuclei show a statistically significant correlation with the local projected galaxy density within the cluster, such that younger ages are predominantly observed outside of the high-density central cluster region. The α-element abundance ratios are consistent with solar for both nuclei and galactic main bodies.

We also examine the presence of radial gradients in the SSP parameters for a subset of 13 dEs (up to 1.2 kpc or 15 arcsec radius). We notice two different types of gradients, namely smooth profiles that include the nucleus, and profiles where a break occurs between the nucleus and the rest of the galaxy. Nevertheless, an overall trend of increasing age and decreasing metallicity with radius exists, consistent with earlier studies. The α-abundance ratio as function of radius is consistent with no gradient.

Possible formation scenarios for the nuclei of dEs are discussed. The young and metal-enhanced population of nuclei suggests that these might have formed at later epochs, or the termination of star formation activity in the nuclei might have occurred relatively late, perhaps due to continuous infall of gas into the central potential well. Our stellar population analysis suggests that the merging of globular clusters is not an appropriate scenario for the formation of most dE nuclei, at least not for the brighter dEs. We speculate that there might be different formation processes which are responsible for the formation of dEs and their nuclei depending on their luminosity.

Based on observations collected at the European Organization for Astronomical Research in the Southern hemisphere, Chile (programme 078.B-0178). HerMES: SPIRE emission from radio-selected active galactic nuclei


Abstract Copyright: 2011 The Authors Monthly Notices of the Royal Astronomical Society2011 RAS

Journal keyword(s): galaxies: clusters: individual: Virgo - galaxies: dwarf - galaxies: elliptical and lenticular, cD - galaxies: evolution - galaxies: formation - galaxies: stellar content

Simbad objects: 34

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Number of rows : 34

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 IC 3097 G 12 17 01.1061542677 +09 24 27.174257881   15.3       ~ 28 0
2 IC 3131 G 12 18 50.9015144446 +07 51 43.052463249   14.8       ~ 54 0
3 IC 781 GiG 12 20 03.2950902737 +14 57 41.410111477   14.8       ~ 53 0
4 IC 783 GiG 12 21 38.7930527227 +15 44 42.343541431   14.60     12.6 ~ 82 1
5 IC 783A GiC 12 22 19.6161424494 +15 44 00.771231005   15.85       ~ 34 0
6 LEDA 40368 GiC 12 24 24.7 +15 04 23   21       ~ 13 0
7 IC 3328 GiP 12 25 57.964 +10 03 13.37   14.9       ~ 145 0
8 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 5876 0
9 NGC 4415 GiG 12 26 40.4850067522 +08 26 08.578644376   14.2       ~ 95 0
10 IC 3369 GiG 12 27 16.9356456625 +16 01 28.142966991   15.1       ~ 43 0
11 LEDA 1333286 G 12 29 14.6518650361 +07 52 39.050707649   16       ~ 24 0
12 GRDG +12 52 GiC 12 29 23.5153719439 +12 27 02.898413946   16 15.29   14.16 ~ 84 0
13 2MASX J12300506+0804241 G 12 30 05.0713836198 +08 04 23.973879851   16.82 15.13     ~ 69 0
14 [FAB2017] NGC4486 S643 GlC 12 30 07.5690843498 +12 36 30.996360221           ~ 23 0
15 NGC 4482 GiG 12 30 10.3250399673 +10 46 46.084712572   14.2       ~ 150 0
16 IC 3435 GiC 12 30 39.792 +15 07 47.29   15.7       ~ 29 0
17 IC 3437 GiC 12 30 45.9045107280 +11 20 35.360387546   15.5       ~ 48 0
18 [JDJ2006] 3 G 12 30 57.3833546242 +12 25 44.499140903   19.32 17.97     ~ 42 0
19 LEDA 41391 G 12 31 01.1242415364 +07 43 23.520155256   16 16.59     ~ 18 0
20 [SFH81] 417 G 12 31 01.4778575124 +12 19 24.597519380     19.33     ~ 22 0
21 [JDJ2006] 4 GlC 12 31 04.4757913483 +11 56 36.488486778           ~ 21 0
22 [JDJ2006] 5 GlC 12 31 11.8766910181 +12 41 01.081447941           ~ 26 0
23 IC 3443 GiC 12 31 15.7338208652 +12 19 54.409742135   16.15 14.95   13.74 ~ 61 0
24 2MASX J12311932+1244174 GiC 12 31 19.329 +12 44 17.50   17 15.87   14.82 ~ 27 0
25 IC 3442 GiG 12 31 20.1847539251 +14 06 54.716926859   15.4       ~ 91 0
26 [JDJ2006] 6 GlC 12 31 28.3597374414 +12 25 03.599290701           ~ 21 0
27 LEDA 41495 GiC 12 31 52.0047574904 +12 28 54.478709052   16.62 15.52   14.44 ~ 40 0
28 2MASS J12315289+1215589 GlC 12 31 52.8978463348 +12 15 59.053574946           ~ 39 0
29 IC 3461 GiG 12 32 02.747 +11 53 23.16   15.4 14.88   13.3 ~ 117 0
30 LEDA 42046 G 12 36 24.781 +10 23 04.75   16       ~ 70 0
31 IC 3633 GiG 12 40 11.2497201632 +09 53 46.052380646   15.4       ~ 67 0
32 IC 3652 GiG 12 40 58.5600973863 +11 11 04.081313393   15.1       ~ 103 0
33 NGC 4637 GiP 12 42 54.097 +11 26 17.84   16.0       ~ 29 1
34 IC 3735 G 12 45 20.376 +13 41 33.74   15.1       ~ 77 0

    Equat.    Gal    SGal    Ecl

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2020.09.25-09:51:45

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