EDP Sciences
Free access
Issue
A&A
Volume 382, Number 3, February II 2002
Page(s) 860 - 871
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20011782


A&A 382, 860-871 (2002)
DOI: 10.1051/0004-6361:20011782

(Sub)millimetre emission from NGC 1569 : An abundance of very small grains

U. Lisenfeld1, F. P. Israel2, J. M. Stil2, 3 and A. Sievers1

1  IRAM, Avendida Divina Pastora 7, N.C., 18012 Granada, Spain
2  Sterrewacht Leiden, Postbus 9513, 2300 RA Leiden, The Netherlands
3  Physics Department, Queen's University, Kingston ON K7L 4P1, Canada

(Received 18 May 2001 / Accepted 5 December 2001 )

Abstract
We present new data of the dwarf galaxy NGC 1569 at 450  $\mu$m, 850  $\mu$m and 1200  $\mu$m taken with SCUBA at the JCMT and the bolometer array at the IRAM 30 m telescope. After including data from IRAS at 12, 25, 60 and 100  $\mu$m, we have successfully fitted the dust grain population model of Désert et al. (1990) to the observed midinfrared-to-millimetre spectrum. The fit requires a combination of both large and very small grains exposed to a strong radiation field as well as an enhancement of the number of very small grains relative to the number of large grains. We interpret this as the consequence of large grain destruction due to shocks in the turbulent interstellar medium of NGC 1569 . The contribution of polyaromatic hydrocarbons (PAH's) is found to be negligible. Comparison of the dust emission maps with an HI map of similar resolution shows that both dust and molecular gas distributions peak close to the radio continuum maximum and at a minimum in the HI distribution. From a comparison of these three maps and assuming that the gas-to-dust mass ratio is the same everywhere, we estimate the ratio of molecular hydrogen column density to integrated CO intensity to be about 25-30 times the local Galactic value. The gas-to-dust ratio is 1500-2900, about an order of magnitude higher than in the Solar Neighbourhood.


Key words: galaxies: individual: NGC 1569 -- galaxies: ISM -- galaxies: irregular -- ISM: dust, extinction

Offprint request: U. Lisenfeld, ute@iram.es

SIMBAD Objects



© ESO 2002

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.