Low Metallicity Indicates that the Hypervelocity Star HE 0437-5439 was Ejected from the LMC
Abstract
We measure the metallicity of the unusual hypervelocity star HE 0437-5439 from high resolution spectroscopy to be half-solar. We determine a spectral type of B2 IV-III for the star and derive an effective temperature Teff= 21,500 +/- 1,000 K and a surface gravity log(g) = 3.7 +/- 0.2 (cgs). We also present BV time series photometry and find the star to be non-variable at the 0.02 mag level. We refine the magnitude of the hypervelocity star to V=16.36+/-0.04 mag, with a color B-V=-0.23+/-0.03 mag, confirming its early-type nature. Our metallicity result establishes the origin of HE 0437-5439 in the Large Magellanic Cloud and implies the existence of a massive black hole somewhere in this galaxy.
Keywords
Cite
@article{arxiv.0712.1825,
title = {Low Metallicity Indicates that the Hypervelocity Star HE 0437-5439 was Ejected from the LMC},
author = {Alceste Z. Bonanos and Mercedes Lopez-Morales and Ian Hunter and Robert S. I. Ryans},
journal= {arXiv preprint arXiv:0712.1825},
year = {2009}
}
Comments
12 pages, 3 figures, 1 table; accepted to ApJL. Added 2 coauthors & full abundance analysis. Results are strengthened