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.

12 pages, 3 figures, 1 table; accepted to ApJL. Added 2 coauthors & full abundance analysis. Results are strengthened

References in corpus (3)

• Chemical Abundances of Luminous Cool Stars in the Galactic Center from High-Resolution Infrared Spectroscopy
• Variability of Young Massive Stars in the Galactic Super Star Cluster Westerlund 1
• Hypervelocity A & B Stars should be slow rotators

Cited by in corpus (6)

• Kinematics of the old stellar population at the Galactic Center
• Hypervelocity Stars: From the Galactic Center to the Halo
• Runaway and hypervelocity stars in the Galactic halo: Binary rejuvenation and triple disruption
• Binary dynamics near a massive black hole
• The Anisotropic Spatial Distribution of Hypervelocity Stars
• 'Slow' and Fast Rotators among Hypervelocity Stars