EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 433/1 Article
Free access article

Issue A&A
Volume 433, Number 1, April I 2005
Page(s) L1 - L4
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200500026



A&A 433, L1-L4 (2005)
DOI: 10.1051/0004-6361:200500026

Letter

A dwarf galaxy with a giant HI disk

A. Begum1, J. N. Chengalur1 and I. D. Karachentsev2

1  National Centre for Radio Astrophysics, Post Bag 3, Ganeshkhind, Pune 411 007, India
    e-mail: ayesha@ncra.tifr.res.in
2  Special Astrophysical Observatory, Nizhnii Arkhys 369167, Russia

(Received 7 January 2005 / Accepted 1 February 2005)

Abstract
We present Giant Meterwave Radio Telescope (GMRT) HI 21 cm images of a nearby dwarf irregular galaxy NGC 3741 ( $M_B \sim -13.13$) which show it to have a gas disk that extends to ~8.3 times its Holmberg radius. This makes it probably the most extended gas disk known. Our observations allow us to derive the rotation curve (which is flat in the outer regions) out to ~38 optical scale lengths. NGC 3741 has a dynamical mass to light ratio of ~107 and is one of the "darkest" irregular galaxies known. However, the bulk of the baryonic mass in NGC 3741 is in the form of gas and the ratio of the dynamic mass to the baryonic mass (~8), falls within the range that is typical for galaxies. Thus the dark matter halo of NGC 3741 has acquired its fair share of baryons, but for some reason, these baryons have been unable to collapse to form stars. A comparison of NGC 3741's dark halo properties with those of a sample of galaxies with well measured rotation curves suggests that if one has to reconcile the observations with the expectation that low mass galaxies suffer fractionally greater baryon loss then baryon loss from halos occurs in such a way that, in the net, the remaining baryons occupy a fractionally smaller volume of the total halo.


Key words: galaxies: dwarf -- galaxies: kinematics and dynamics -- galaxies: individual: NGC 3741

SIMBAD Objects



© ESO 2005


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.