A massive spiral galaxy in the zone of avoidance
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2006
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Monthly Notices of the Royal Astronomical Society
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Oxford University Press
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University of Cape Town
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Abstract
We report the discovery of a very HI-massive disc galaxy, HIZOAJ0836-43, at a velocity of vhel = 10689kms-1, corresponding to a distance of 148Mpc (assuming H0 = 75kms-1Mpc-1). It was found during the course of a systematic HI survey of the southern Zone of Avoidance (ZOA) (|b| <= 5°) with the multibeam system at the 64-m Parkes radio telescope. Follow-up observations with the Australia Telescope Compact Array reveal an extended HI disc. We derive an HI mass of 7.5 × 1010Msolar. Using the HI radius, we estimate a total dynamical mass of 1.4 × 1012Msolar, similar to the most massive known disc galaxies such as Malin1. HIZOAJ0836-43 lies deep in the ZOA where the optical extinction is very high, AB = 9.8mag. However, in the near-infrared (NIR) wavebands, where the extinction is considerably lower, HIZOAJ0836-43 is clearly detected by both the Deep Near Infrared Survey of the Southern Sky (DENIS) and Two-Micron All-Sky Survey (2MASS). Deep Anglo-Australian Telescope NIR (Ks and H band) images show that HIZOAJ0836-43 is an inclined disc galaxy with a prominent bulge (scalelength 2.5arcsec or 1.7kpc), and an extended disc (scalelength 7arcsec or 4.7kpc) which can be traced along the major axis out to a radius of 20arcsec or 13.4kpc (at 20magarcsec-2 in Ks). The HI disc is much more extended, having a radius of 66kpc at 1Msolarpc-2. Detections in the radio continuum at 1.4GHz and at 60μm (IRAS) are consistent with HIZOAJ0836-43 forming stars at a rate of ~35Msolaryr-1. We compare the properties of HIZOAJ0836-43 with those of the most HI-massive galaxies currently known, UGC4288, UGC1752 and Malin1, all of which are classified as giant low surface brightness galaxies.
The observations were obtained with the Australia Telescope which is funded by the Commonwealth of Australia for operations as a National Facility managed by CSIRO.
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This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society (ISSN: 0035-8711) ©: 2006 Donley et al. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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Donley, J. L., Koribalski, B. S., Staveley-Smith, L., Kraan-Korteweg, R. C., Schröder, A., & Henning, P. A. (2006). A massive spiral galaxy in the Zone of Avoidance. Monthly Notices of the Royal Astronomical Society, 369(4), 1741-1754.