Advanced

Probing the nature of the G1 clump stellar overdensity in the outskirts of M31

Faria, Daniel LU ; Johnson, Rachel A.; Ferguson, Annette M. N.; Irwin, Mike J.; Ibata, Rodrigo A.; Johnston, Kathryn V.; Lewis, Geraint F. and Tanvir, Nial R. (2007) In Astronomical Journal 133(4). p.1275-1286
Abstract
We present deep Hubble Space Telescope ACS observations of the G1 clump, a distinct stellar overdensity lying at similar to 30 kpc along the southwestern major axis of M31, close to the G1 globular cluster ( from the work of Ferguson and coworkers). Our well-populated color-magnitude diagram reaches similar to 7 mag below the red giant branch tip with 90% completeness, and allows the detection of various morphological features that can be used to derive detailed constraints on the age and metallicity of the constituent stellar population. We find that the color-magnitude diagram is best described spread in metallicity is constrained to be P = 0.5 dex. The star formation rate in this region has declined over time, with the bulk of the... (More)
We present deep Hubble Space Telescope ACS observations of the G1 clump, a distinct stellar overdensity lying at similar to 30 kpc along the southwestern major axis of M31, close to the G1 globular cluster ( from the work of Ferguson and coworkers). Our well-populated color-magnitude diagram reaches similar to 7 mag below the red giant branch tip with 90% completeness, and allows the detection of various morphological features that can be used to derive detailed constraints on the age and metallicity of the constituent stellar population. We find that the color-magnitude diagram is best described spread in metallicity is constrained to be P = 0.5 dex. The star formation rate in this region has declined over time, with the bulk of the stellar mass having formed > 6 Gyr ago. Nonetheless, a nonnegligible mass fraction (approximate to 10%) of the population has formed in the last 2 Gyr. We discuss the nature of the G1 clump in light of these new stellar population constraints and argue that the combination of stellar content and physical size make it unlikely that the structure is the remnant of an accreted dwarf galaxy. Instead, the strong similarity between the stellar content of the G1 clump and that of the M31 outer disk suggests that the substructure is a fragment of the outer disk, perhaps torn off from the main body during a past accretion/merger event; this interpretation is consistent with extant kinematical data. If this interpretation is correct, our analysis of the stellar content provides further evidence that the outskirts of large disk galaxies have been in place for a significant time. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
galaxies : structure, galaxies : stellar content, : individual ( M31), galaxies, galaxies : halos, galaxies : evolution, galaxies : formation
in
Astronomical Journal
volume
133
issue
4
pages
1275 - 1286
publisher
The American Astronomical Society
external identifiers
  • wos:000245543700008
  • scopus:34247467071
ISSN
1538-3881
DOI
10.1086/511156
language
English
LU publication?
yes
id
3bc44cc8-c557-4442-a1ed-0db45e7e80ee (old id 666591)
date added to LUP
2007-12-10 11:23:15
date last changed
2017-07-30 03:39:07
@article{3bc44cc8-c557-4442-a1ed-0db45e7e80ee,
  abstract     = {We present deep Hubble Space Telescope ACS observations of the G1 clump, a distinct stellar overdensity lying at similar to 30 kpc along the southwestern major axis of M31, close to the G1 globular cluster ( from the work of Ferguson and coworkers). Our well-populated color-magnitude diagram reaches similar to 7 mag below the red giant branch tip with 90% completeness, and allows the detection of various morphological features that can be used to derive detailed constraints on the age and metallicity of the constituent stellar population. We find that the color-magnitude diagram is best described spread in metallicity is constrained to be P = 0.5 dex. The star formation rate in this region has declined over time, with the bulk of the stellar mass having formed > 6 Gyr ago. Nonetheless, a nonnegligible mass fraction (approximate to 10%) of the population has formed in the last 2 Gyr. We discuss the nature of the G1 clump in light of these new stellar population constraints and argue that the combination of stellar content and physical size make it unlikely that the structure is the remnant of an accreted dwarf galaxy. Instead, the strong similarity between the stellar content of the G1 clump and that of the M31 outer disk suggests that the substructure is a fragment of the outer disk, perhaps torn off from the main body during a past accretion/merger event; this interpretation is consistent with extant kinematical data. If this interpretation is correct, our analysis of the stellar content provides further evidence that the outskirts of large disk galaxies have been in place for a significant time.},
  author       = {Faria, Daniel and Johnson, Rachel A. and Ferguson, Annette M. N. and Irwin, Mike J. and Ibata, Rodrigo A. and Johnston, Kathryn V. and Lewis, Geraint F. and Tanvir, Nial R.},
  issn         = {1538-3881},
  keyword      = {galaxies : structure,galaxies : stellar content,: individual ( M31),galaxies,galaxies : halos,galaxies : evolution,galaxies : formation},
  language     = {eng},
  number       = {4},
  pages        = {1275--1286},
  publisher    = {The American Astronomical Society},
  series       = {Astronomical Journal},
  title        = {Probing the nature of the G1 clump stellar overdensity in the outskirts of M31},
  url          = {http://dx.doi.org/10.1086/511156},
  volume       = {133},
  year         = {2007},
}