Letter to the Editor

Dust in the bright supernova remnant N49 in the LMC^*

¹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA e-mail: otsuka@stsci.edu
² School of Physical & Geographical Sciences, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG, UK
³ Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
⁴ Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125, USA
⁵ Stratospheric Observatory for Infrared Astronomy, Universities Space Research Association, Mail Stop 211-3, Moffett Field, CA 94035, USA
⁶ CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, 91191 Gif-sur-Yvette, France
⁷ Steward Observatory, University of Arizona, 933 North Cherry Ave., Tucson, AZ 85721, USA
⁸ Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics & Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
⁹ Department of Astronomy, Cornell University, Ithaca, NY 14853, USA

Received: 31 March 2010
Accepted: January 1900

Abstract

We investigate the dust associated with the supernova remnant (SNR) N49 in the Large Magellanic Cloud (LMC) as observed with the Herschel Space Observatory. N49 is unusually bright because of an interaction with a molecular cloud along its eastern edge. We have used PACS and SPIRE to measure the far IR flux densities of the entire SNR and of a bright region on the eastern edge of the SNR where the SNR shock is encountering the molecular cloud. Using these fluxes supplemented with archival data at shorter wavelengths, we estimate the dust mass associated with N49 to be about 10 . The bulk of the dust in our simple two-component model has a temperature of 20–30 K, similar to that of nearby molecular clouds. Unfortunately, as a result of the limited angular resolution of Herschel at the wavelengths sampled with SPIRE, the uncertainties are fairly large. Assuming this estimate of the dust mass associated with the SNR is approximately correct, it is probable that most of the dust in the SNR arises from regions where the shock speed is too low to produce significant X-ray emission. The total amount of warm 50–60 K dust is ~0.1 or 0.4 , depending on whether the dust is modeled in terms of carbonaceous or silicate grains. This provides a firm lower limit to the amount of shock heated dust in N49.