Comments on a faint old stellar system at 150 kpc

Free access article

Issue		A&A Volume 471, Number 3, September I 2007


Page(s)		805 - 806
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20077369

A&A 471, 805-806 (2007)
DOI: 10.1051/0004-6361:20077369

Comments on a faint old stellar system at 150 kpc

H. Kamaya

Department of Earth and Ocean Sciences, School of Applied Sciences, National Defense Academy of Japan, Yokosuka 239-8686, Japan ( Department of Astronomy, School of Science, Kyoto University, Sakyo-Ku, Kyoto 606-8502, Japan, before 2007 April.)
e-mail: kamaya@nda.ac.jp

(Received 28 February 2007 / Accepted 2 June 2007 )

Abstract
Context.Recent study of SDSS J1257+3419 has revealed that this stellar system is either a faint and small dwarf galaxy or a faint and widely extended globular cluster.
Aims.In this short note, the author suggests that this system is one of the smallest dwarf spheroidals (dSphs) in the Milky Way.
Methods.We re-examine some observational quantities of this object and check whether it can be bound system.
Results. As a result, we find the mass of SDSS J1257+3419 is the lowest of dSphs in the Milky Way, and its mass density is typical of dSphs. Important is that the tidal radius of SDSS J1257+3419 is much larger than its half-light radius. That is, this very small dSph can be bound by its own gravity.

Key words: Galaxy: halo -- galaxies: dwarf

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.