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The Circumnuclear Star Formation Environment of NGC 6946: Br γ and H_2 Results from Keck Integral Field Spectroscopy

Tsai, Chao-Wei and Turner, Jean L. and Beck, Sara C. and Meier, David S. and Wright, Shelley A. (2013) The Circumnuclear Star Formation Environment of NGC 6946: Br γ and H_2 Results from Keck Integral Field Spectroscopy. Astrophysical Journal, 776 (2). Art. No. 70. ISSN 0004-637X. doi:10.1088/0004-637X/776/2/70.

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We present a 3-dimensional data cube of the K band continuum and the Brγ, H_2 S(0) and S(1)lines within the central 18.”5 x 13.”8 (520 pc x 390 pc) region of NGC6946. Data were obtained using OSIRIS, a near-infrared Integral Field Unit at Keck Observatory, with Laser Guide Star Adaptive Optics. The 0."3 resolution allows us to investigate the stellar bulge and the forming star clusters in the nuclear region on 10 pc scales. We detect giant H II regions associated with massive young star clusters in the nuclear spiral/ring (R~30 pc) and in the principal shocks along the nuclear bar. Comparisons of the Br γ fluxes with Pa α line emission and radio continuum indicate A_K ~ 3, A_V ~ 25 for the nuclear star forming regions. The most luminous H II regions are restricted to within 70 pc of the center, despite the presence of high gas columns at larger radii (R~200 pc). H_2 emission is restricted to clouds within R~60 pc of the center, and in this sense resembles the distribution of the HCN line emission. We propose that gas-assisted migration of the young star clusters is contributing to the buildup of the nuclear bar and nuclear star cluster (R<30 pc) in this galaxy.

Item Type:Article
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URLURL TypeDescription Paper
Tsai, Chao-Wei0000-0002-9390-9672
Turner, Jean L.0000-0003-4625-2951
Meier, David S.0000-0001-9436-9471
Wright, Shelley A.0000-0003-1034-8054
Additional Information:© 2013 American Astronomical Society. Received 2012 October 5; accepted 2013 August 8; published 2013 September 27. The authors thank the anonymous referee for a very thorough and helpful review. CWT acknowledges Tuan Do for his help in OSIRIS observation. We are grateful for discussions on these results at a TIARA conference with Steve Maciejewski and Bruce Elmegreen. This work is based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation. The authors also wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community; we are most fortunate to have the opportunity to conduct observations from this mountain. The 18 cm radio data reported in this paper is based on archived data made with MERLIN, a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC. Facilities: Keck (OSIRIS), VLA, MERLIN.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: individual (NGC 6946); galaxies: starburst; galaxies: star clusters: general; H II regions; infrared: galaxies; radio continuum: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20130829-103404193
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Official Citation:The Circumnuclear Star Formation Environment of NGC 6946: Br γ and H2 Results from Keck Integral Field Spectroscopy Chao-Wei Tsai et al. 2013 ApJ 776 70
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:40992
Deposited By: Tony Diaz
Deposited On:30 Aug 2013 17:56
Last Modified:10 Nov 2021 04:24

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