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arXiv · 1404.5713

Quantitative Spectroscopic J-band Study of Red Supergiants in Perseus OB-1

J. Zachary Gazak·Ben Davies·Rolf Kudritzki·Maria Bergemann·Bertrand Plez
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Abstract

We demonstrate how the metallicities of red supergiant (RSG) stars can be measured from quantitative spectroscopy down to resolutions of ~3000 in the J-band. We have obtained high resolution spectra on a sample of the RSG population of h and chi Persei, a double cluster in the solar neighborhood. We show that careful application of the MARCS model atmospheres returns measurements of Z consistent with solar metallicity. Using two grids of synthetic spectra--one in pure LTE and one with NLTE calculations for the most important diagnostic lines--we measure Z = +0.04 +/- 0.10 (LTE) and Z = -0.04 +/- 0.08 (NLTE) for the sample of eleven RSGs in the cluster. We degrade the spectral resolution of our observations and find that those values remain consistent down to resolutions of less than R of 3000. Using measurements of effective temperatures we compare our results with stellar evolution theory and find good agreement. We construct a synthetic cluster spectrum and find that analyzing this composite spectrum with single-star RSG models returns an accurate metallicity. We conclude that the RSGs make ideal targets in the near infrared for measuring the metallicities of star forming galaxies out to 7-10 Mpc and up to ten times farther by observing the integrated light of unresolved super star clusters.

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J. Zachary Gazak, Ben Davies, Rolf Kudritzki, Maria Bergemann, Bertrand Plez. 2014-04-23. Quantitative Spectroscopic J-band Study of Red Supergiants in Perseus OB-1. https://doi.org/10.1088/0004-637x%2F788%2F1%2F58

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