A&A 432, 1-14 (2005)
DOI: 10.1051/0004-6361:20041488

Multi-density model of the ionised gas in NGC 253 using radio recombination lines

Niruj R. Mohan^{1, 2, 3}, W. M. Goss⁴ and K. R. Anantharamaiah<sup>2

1</sup>  Institut d'Astrophysique de Paris, 98 bis boulevard Arago, 75014 Paris, France
²  Raman Research Institute, C.V. Raman Avenue, Sadashivanagar Post Office, Bangalore 560080, India
³  Joint Astronomy Program, Department of Physics, Indian Institute of Science, Bangalore 560012, India
⁴  National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA
    e-mail: mgoss@aoc.nrao.edu

(Received 17 June 2004 / Accepted 26 October 2004)

Abstract
We have imaged the H92 (8.3 GHz), H75 (15 GHz), and H166 (1.4 GHz) Radio Recombination Lines (RRLs) from NGC 253 at resolutions of 4.5 pc (0.4 ) , 2.5 pc (0.2 ) and 53 pc (4.5 ) respectively. The H92 line arises from individual compact sources, most of which possess radio continuum counterparts. The line widths range from ~200 km s ^-1 for the sources near the radio nucleus to 70-100 km s ^-1 for the extranuclear ones. These lines are emitted by gas at a density ~10 ⁴ cm ^-3. The remainder of the cm-wave RRLs arise in lower density gas (~500 cm ^-3) with a higher area filling factor and with ten times higher mass. A third component of higher density gas ( >10 ⁴ cm ^-3) is required to explain the mm-wave RRLs.

Key words: galaxies: individual: NGC 253 -- galaxies: ISM -- galaxies: starburst -- radio lines: galaxies -- radio lines: ISM

SIMBAD Objects

© ESO 2005

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.