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Discovery of low-metallicity stars in the central parsec of the Milky Way by Do, Tuan; Kerzendorf, Wolfgang; Winsor, Nathan; Støstad, Morten; Morris, Mark R.; Lu, Jessica R.; Ghez, Andrea M. is a scholarly article available to read on EtoBox.

What is Discovery of low-metallicity stars in the central parsec of the Milky Way about?

We present a metallicity analysis of 83 late-type giants within the central 1 pc of the Milky Way. K-band spectroscopy of these stars were obtained with the medium-spectral resolution integral-field spectrograph NIFS on Gemini North using laser-guide star adaptive optics. Using spectral template fitting with the MARCS synthetic spectral grid, we find that there is large variation in metallicity, with stars ranging from [M/H] $<$ -1.0 to above solar metallicity. About 6\% of the stars have [M/H] $<$ -0.5. This result is in contrast to previous observations, with smaller samples, that show stars at the Galactic center have approximately solar metallicity with only small variations. Our current measurement uncertainties are dominated by systematics in the model, especially at [M/H] $>$ 0, where there are stellar lines not represented in the model. However, the conclusion that there are low metallicity stars, as well as large variations in metallicity is robust. The metallicity may be an indicator of the origin of these stars. The low-metallicity population is consistent with that of globular clusters in the Milky Way, but their small fraction likely means that globular cluster infall

Author

Do, Tuan; Kerzendorf, Wolfgang; Winsor, Nathan; Støstad, Morten; Morris, Mark R.; Lu, Jessica R.; Ghez, Andrea M.

Published

2015

Language

EN