Journal Article

Determining the extragalactic extinction law with SALT – II. Additional sample*

Ido Finkelman, Noah Brosch, Alexei Y. Kniazev, Petri Väisänen, David A. H. Buckley, Darragh O'Donoghue, Amanda Gulbis, Yas Hashimoto, Nicola Loaring, Encarni Romero-Colmenero and Ramotholo Sefako

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 409, issue 2, pages 727-736
Published in print December 2010 | ISSN: 0035-8711
Published online November 2010 | e-ISSN: 1365-2966 | DOI:
Determining the extragalactic extinction law with SALT – II. Additional sample*

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We present new results from an ongoing programme to study the dust extragalactic extinction law in E/S0 galaxies with dust lanes with the Southern African Large Telescope (SALT) during its performance verification phase. The wavelength dependence of the dust extinction for seven galaxies is derived in six spectral bands ranging from the near-ultraviolet atmospheric cut-off to the near-infrared. The derivation of an extinction law is performed by fitting model galaxies to the unextinguished parts of the image in each spectral band, and subtracting from these the actual images. We compare our results with the derived extinction law in the Galaxy and find them to run parallel to the Galactic extinction curve with a mean total-to-selective extinction value of RV= 2.71 ± 0.43. We use total optical extinction values to estimate the dust mass for each galaxy, compare these with dust masses derived from IRAS measurements, and find them to range from 104 to 107 M. We study the case of the well-known dust-lane galaxy NGC 2685 for which Hubble Space Telescope/Wide Field Planetary Camera 2 (HST/WFPC2) data are available to test the dust distribution on different scales. Our results imply a scale-free dust distribution across the dust lanes, at least within ∼1 arcsec (∼60 pc) regions.

Keywords: dust, extinction; galaxies: elliptical and lenticular, cD; galaxies: ISM

Journal Article.  5542 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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