1998/03/13 by Amy E. Nelson, Dennis Zaritsky, R. M. Cutri +1 · 2 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/300386
31 pages, 9 figures, AASTEX (aaspp4), accepted for publication in the Astronomical Journal
arxiv created 1998/03/13 · openalex publication_date 1998/06/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We measure the extent of 100 μm galactic emission in two independent galaxy samples using the IRAS 100 μm Sky Survey images and constrain the distribution of dust at large (≲30 kpc) radii. The first sample consists of 90 nearby ( v < 6000 km s -1 ) galaxies from the Third Reference Catalogue of Bright Galaxies with similar angular sizes and absolute luminosities (5' ≤ D 25 ≤ 10' and -22.5 ≤ M B ≤ -18) that are isolated in the 100 μm images. The second sample consists of 24 local galaxies ( v < 1500 km s -1 , 10' ≤ D 25 ≤ 30'). We rescale the 100 μm images of these galaxies using their optical diameters, D 25 , rotate the images using their optical major-axis position angle, construct the mean and median images, and rebin the final images into polar coordinates to study the 100 μm emission as a function of radius and azimuthal angle. We find that the 100 μm emission extends at least to radii of 33 kpc (2 σ detection) for the typical galaxy in the 5'–10' sample and to 21 kpc (2 σ detection) in the 10'–30' sample ( H 0 = 75 km s -1 Mpc -1 ). In both samples, the emission is preferentially elongated along the optical major axis. We fit an exponential to the 100 μm emission along the major axis and measure a scale length of 2.5 ± 0.8 kpc (90% confidence interval). Using a simple model that relates the far-IR emission to the stellar distribution, we examine the range of acceptable dust mass distributions allowed by our data and conclude that the dust is more extended than the starlight.