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II Zw 40 – 30 Doradus on Steroids

Published online by Cambridge University Press:  28 July 2017

Claus Leitherer ,
Janice C. Lee  and
Emily M. Levesque
Claus Leitherer
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA email: [email protected], [email protected]
Janice C. Lee
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA email: [email protected], [email protected]
Emily M. Levesque
Affiliation:
Dept. of Astronomy, University of Washington C327, Seattle, WA 98195, USA email: [email protected]
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Abstract

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We obtained HST COS G140L spectra of the enigmatic nearby blue compact dwarf galaxy II Zw 40. The galaxy hosts a nuclear super star cluster embedded in a radio-bright nebula, similar to those observed in the related blue compact dwarfs NGC 5253 and Henize 2-10. The ultraviolet spectrum of II Zw 40 is exceptional in terms of the strength of He II 1640, O III] 1666 and C III] 1909. We determined reddening, age, and the cluster mass from the ultraviolet data. The super nebula and the ionizing cluster exceed the ionizing luminosity and stellar mass of the local benchmark 30 Doradus by an order of magnitude. Comparison with stellar evolution models accounting for rotation reveals serious short-comings: these models do not account for the presence of Wolf-Rayet-like stars at young ages observed in II Zw 40. Photoionization modeling is used to probe the origin of the nebular lines and determine gas phase abundances. C/O is solar, in agreement with the result of the stellar-wind modeling.

Keywords

galaxies: dwarfgalaxies: starburstgalaxies: stellar content
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 12 , Symposium S329: The Lives and Death-Throes of Massive Stars , November 2016 , pp. 322 - 326
Copyright
Copyright © International Astronomical Union 2017 

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