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Imaging and spectroscopy of the LMC He II nebula N 44C and its ionizing star

Published online by Cambridge University Press:  25 May 2016

Vanessa C. Galarza ,
Donald R. Garnett  and
You-Hua Chu
Vanessa C. Galarza
Affiliation:
New Mexico State University, Las Cruces, NM 88003, USA
Donald R. Garnett
Affiliation:
University of Arizona, Tucson, AZ 85721, USA
You-Hua Chu
Affiliation:
University of Illinois, Urbana, IL 61801, USA

Abstract

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We present results from new HST imaging and spectroscopy of the peculiar Large Magellanic Cloud H II region N 44C and its ionizing star. While this nebula exhibits strong He II recombination emission, the source of the He+ ionizing photons has not been found. The UV spectrum of the ionizing star suggests an approximate spectral class of 07–08; the UV Si IV, He II, and N IV features do not show P-Cygni profiles, indicating that the ionizing star is not a supergiant. No companion star has yet been detected. Ground-based and HST optical spectroscopy of the ionized gas shows that the nebular abundances of C, N, O and He are not anomalous relative to other LMC H II regions, suggesting that no previous WR/SN companion has disappeared. Echelle spectroscopy has also ruled out the presence of high velocity shocked gas. Deep ROSAT imaging shows no X-ray point source in this location. The “fossil X-ray binary” hypothesis of Pakull & Motch (1989) remains the best explanation for the ionization of this nebula; however, convincing evidence for this hypothesis remains elusive.

Type
Part 4. Wolf-Rayet stars and other hot massive stars in the Galactic Center and in Local Group giant H II regions (individual stars)
Information
Symposium - International Astronomical Union , Volume 193: Wolf-Rayet Phenomena in Massive Stars and Starburst Galaxies , 1999 , pp. 480 - 481
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

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