Extragalactic Stellar Astronomy with the Brightest Stars in the Universe

Abstract

A supergiants are objects in transition from the blue to the red (and vice versa) in the uppermost HRD. They are the intrinsically brightest "normal" stars at visual light with absolute visual magnitudes up to -9. They are ideal to study young stellar populations in galaxies beyond the Local Group to determine chemical composition and evolution, interstellar extinction, reddening laws and distances. We discuss most recent results on the quantitative spectral analysis of such objects in galaxies beyond the Local Group based on medium and low resolution spectra obtained with the ESO VLT and Keck. We describe the analysis method including the determination of metallicity and metallicity gradients. A new method to measure accurate extragalactic distances based on the stellar gravities and effective temperatures is presented, the flux weighted gravity - luminosity relationship (FGLR). The FGLR is a purely spectroscopic method, which overcomes the untertainties introduced by interstellar extinction and variations of metallicity, which plague all photometric stellar distance determination methods. We discuss the perspectives of future work using the giant ground-based telescopes of the next generation such as the TMT, the GMT and the E-ELT.

arXiv commentInvited review; to appear in "Massive Stars as Cosmic Engines", IAU Symp. 250, ed. F. Bresolin, P. A. Crowther, and J. Puls (Cambridge University Press)

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Cited by in corpus (8)

• Rotating Massive Main-Sequence Stars I: Grids of Evolutionary Models and Isochrones
• Mass loss from hot massive stars
• The VLT-FLAMES Tarantula Survey I: Introduction and observational overview
• Quantitative spectroscopy of Galactic BA-type supergiants. I. Atmospheric parameters
• The flux-weighted gravity-luminosity relationship of blue supergiant stars as a constraint for stellar evolution
• CRIRES high-resolution near-infrared spectroscopy of diffuse interstellar band profiles. Detection of 12 new DIBs in the YJ band and the introduction of a combined ISM sight line and stellar analysis approach
• Impact of binary interaction on the evolution of blue supergiants
• Distance and Reddening of the Isolated Dwarf Irregular Galaxy NGC 1156