The star pile in Abell 545
Abstract
Context: Struble (1988, ApJ, 330, L25) found what appeared to be a cD halo without cD galaxy in the center of the galaxy cluster Abell 545. This remarkable feature has been passed almost unnoticed for nearly twenty years.
Aims: Our goal is to review Struble's claim by providing a first (preliminary) photometric and spectroscopic analysis of this “star pile”.
Methods: Based on archival VLT-images and long-slit spectra obtained with Gemini-GMOS, we describe the photometric structure and measure the redshift of the star pile and of the central galaxy.
Results: The star pile is indeed associated with Abell 545. Its velocity is higher by about 1300 km s-1 than that of the central object. The spectra indicate an old, presumably metal-rich population. Its brightness profile is much shallower than that of typical cD-galaxies.
Conclusions: The formation history and the dynamical status of the star pile remain elusive, until high S/N spectra and a dynamical analysis of the galaxy cluster itself become available. We suggest that the star pile might provide an interesting test of the Cold Dark Matter paradigm.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 2007
- DOI:
- 10.1051/0004-6361:20078475
- arXiv:
- arXiv:0709.3633
- Bibcode:
- 2007A&A...475..507S
- Keywords:
-
- galaxies: clusters: individual: A 545;
- galaxies: elliptical and;
- lenticular;
- cD;
- galaxies: intergalactic medium;
- Astrophysics
- E-Print:
- 6 pages, 7 figures. Accepted for publication in A&