A Gravitational Redshift Determination of the Mean Mass of White Dwarfs. DA Stars - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




A Gravitational Redshift Determination of the Mean Mass of White Dwarfs. DA Stars - Astrophysics > Solar and Stellar Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We measure apparent velocities v app of the Halpha and Hbeta Balmer linecores for 449 non-binary thin disk normal DA white dwarfs WDs using opticalspectra taken for the ESO SN Ia Progenitor surveY SPY; Napiwotzki et al.2001. Assuming these WDs are nearby and co-moving, we correct our velocitiesto the Local Standard of Rest so that the remaining stellar motions are random.By averaging over the sample, we are left with the mean gravitational redshift,: we find = = 32.57 +- 1.17 km-s. Using the mass-radiusrelation from evolutionary models, this translates to a mean mass of 0.647+0.013 -0.014 Msun. We interpret this as the mean mass for all DAs. Our resultsare in agreement with previous gravitational redshift studies but aresignificantly higher than all previous spectroscopic determinations except therecent findings of Tremblay and Bergeron 2009. Since the gravitational redshiftmethod is independent of surface gravity from atmosphere models, we investigatethe mean mass of DAs with spectroscopic Teff both above and below 12000 K; fitsto line profiles give a rapid increase in the mean mass with decreasing Teff.Our results are consistent with no significant change in mean mass: ^hot =0.640 +- 0.014 Msun and ^cool = 0.686 +0.035 -0.039 Msun.



Author: Ross E. Falcon, D. E. Winget, M. H. Montgomery, Kurtis A. Williams

Source: https://arxiv.org/







Related documents