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Gas and star formation in the Circinus galaxy

For, B.-Q. and Koribalski, B. S. and Jarrett, T. H. (2012) Gas and star formation in the Circinus galaxy. Monthly Notices of the Royal Astronomical Society, 425 (3). pp. 1934-1950. ISSN 0035-8711. doi:10.1111/j.1365-2966.2012.21416.x.

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We present a detailed study of the Circinus galaxy, investigating its star formation, dust and gas properties, both in the inner and outer disc. To achieve this, we obtained high-resolution Spitzer mid-infrared images with the IRAC (3.6, 5.8, 4.5 and 8.0 μm) and MIPS (24 and 70 μm) instruments and sensitive H i data from the Australia Telescope Compact Array and the 64-m Parkes telescope. These were supplemented by CO maps from the Swedish-ESO Submillimetre Telescope. Because Circinus is hidden behind the Galactic plane, we demonstrate the careful removal of foreground stars as well as large- and small-scale Galactic emission from the Spitzer images. We derive a visual extinction of A_V = 2.1 mag from the spectral energy distribution of the Circinus galaxy and total stellar and gas masses of 9.5 × 10^10 and 9 × 10^(9) M_⊙, respectively. Using various wavelength calibrations, we find obscured global star formation rates between 3 and 8 M_⊙ yr^(−1). Star-forming regions in the inner spiral arms of Circinus, which are rich in H i, are beautifully unveiled in the Spitzer 8 μm image. The latter is dominated by polycyclic aromatic hydrocarbon (PAH) emission from heated interstellar dust. We find a good correlation between the 8 μm emission in the arms and regions of dense H i gas. The (PAH 8 μm)/24 μm surface brightness ratio shows significant variations across the disc of Circinus.

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Jarrett, T. H.0000-0002-4939-734X
Additional Information:© 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS. Accepted 2012 May 30. Received 2012 May 27; in original form 2012 April 2. B-QF is the recipient of a John Stocker Postdoctoral Fellowship from Australia’s Science and Industry Endowment Fund (SIEF). She thanks the generous travel support to Australia from the University of Texas Astronomy Department Cox Excellence Fund and the financial support by CSIRO Astronomy and Space Science during summer 2010.We also thankMichelle Cluver and Tobias Westmeier for helpful discussions. This work is based (in part) on observations made with the Spitzer and research using the NASA/IPAC Extragalactic Database (NED) and IPAC Infrared Science Archive; all are operated by JPL, Caltech, under a contract with the National Aeronautics and Space Administration. Support for this work was provided by NASA through an award issued by JPL/Caltech.
Funding AgencyGrant Number
University of Texas Astronomy Department Cox Excellence FundUNSPECIFIED
CSIRO Astronomy and Space ScienceUNSPECIFIED
Australia Science and Industry Endowment Fund (SIEF)UNSPECIFIED
Subject Keywords:galaxies: individual: Circinus; galaxies: spiral; galaxies: starburst; galaxies: star formation
Issue or Number:3
Record Number:CaltechAUTHORS:20121112-141321098
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Official Citation:For, B.-Q., Koribalski, B. S. and Jarrett, T. H. (2012), Gas and star formation in the Circinus galaxy. Monthly Notices of the Royal Astronomical Society, 425: 1934–1950. doi: 10.1111/j.1365-2966.2012.21416.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35413
Deposited By: Jason Perez
Deposited On:13 Nov 2012 15:40
Last Modified:09 Nov 2021 23:14

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