Revisiting the optical depth of spiral galaxies using the Tully-Fisher B relation
Abstract
Aims. We attempt to determine the optical depth of spiral galaxy disks by a statistical study of new Tully-Fisher data from the ongoing KLUN+ survey, and to clarify the difference between the true and apparent behavior of optical depth. Methods. By utilizing so-called normalized distances, a subsample of the data is identified to be as free from selection effects as possible. For these galaxies, a set of apparent quantities are calculated for face-on positions using the Tully-Fisher diameter and magnitude relations. These values are compared with direct observations to determine the mean value of the parameter C describing the optical depth. Results. The present study suggests that spiral galaxy disks are relatively optically thin tauB = 0.1, at least in the outermost regions, while they appear in general to be optically thick tauB > 1 when the apparent magnitude and average surface brightness are studied statistically.
Keywords
Cite
@article{arxiv.0810.4773,
title = {Revisiting the optical depth of spiral galaxies using the Tully-Fisher B relation},
author = {E. Kankare and M. Hanski and G. Theureau and P. Teerikorpi},
journal= {arXiv preprint arXiv:0810.4773},
year = {2009}
}
Comments
9 pages, 13 figures, accepted for publication in Astronomy & Astrophysics