The potential of Red Supergiants as extra-galactic abundance probes at low spectral resolution - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




The potential of Red Supergiants as extra-galactic abundance probes at low spectral resolution - Astrophysics > Cosmology and Nongalactic Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: Red Supergiants RSGs are among the brightest stars in the local universe,making them ideal candidates with which to probe the properties of their hostgalaxies. However, current quantitative spectroscopic techniques requirespectral resolutions of R>17,000, making observations of RSGs at distancesgreater than 1Mpc unfeasible. Here we explore the potential of quantitativespectroscopic techniques at much lower resolutions, R ~2-3000. We take archivalJ-band spectra of a sample of RSGs in the Solar neighbourhood. In this spectralregion the metallic lines of FeI, MgI, SiI and TiI are prominent, while themolecular absorption features of OH, H 2O, CN and CO are weak. We compare thesedata with synthetic spectra produced from the existing grid of modelatmospheres from the MARCS project, with the aim of deriving chemicalabundances. We find that all stars studied can be unambiguously fit by themodels, and model parameters of log g, effective temperatures Teff,microturbulence and global metal content may be derived. We find that theabundances derived for the stars are all very close to Solar and have lowdispersion, with an average of logZ=0.13+-0.14. The values of Teff fit bythe models are ~150K cooler than the stars- literature values for earlierspectral types when using the Levesque et al. temperature scale, though thistemperature discrepancy has very little systematic effect on the derivedabundances as the equivalent widths EWs of the metallic lines are roughlyconstant across the full temperature range of RSGs. Instead, elementalabundances are the dominating factor in the EWs of the diagnostic lines. Ourresults suggest that chemical abundance measurements of RSGs are possible atlow- to medium-resolution, meaning that this technique is a viableinfrared-based alternative to measuring abundance trends in external galaxies.Abridged



Autor: Ben Davies RIT-Leeds, Rolf-Peter Kudritzki Hawaii, Donald F. Figer RIT

Fuente: https://arxiv.org/







Documentos relacionados