2015/08/31 by J. Maíz Apellániz, Apellániz, J. Maíz · 1 citation
Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR) #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.48550/arxiv.1508.07736
10 pages. To appear in the Memorie della societa astronomica italiana edition dedicated to the EWASS 2015 Special Session 20: 3D structure of the ISM from absorption data in the Gaia Era
arxiv created 2015/08/31 · arxiv updated 2015/09/01
I present results on the interstellar medium towards the O stars observed in five optical spectroscopic surveys: GOSSS, OWN, IACOB, NoMaDS, and CAFÉ-BEANS. I have measured both the amount [E(4405-5495)] and type [R5495] of extinction towards several hundreds of Galactic O stars and verified that the Maíz Apellániz et al. (2014) family of extinction laws provides a significantly better fit to optical+NIR Galactic extinction than either the Cardelli et al. (1989) or the Fitzpatrick (1999) families. R5495 values are concentrated between 3.0 and 3.5 but for low values of E(4405-5495) there is a significant population with larger R5495 associated with H II regions. I have also measured different DIBs and I have found that W(5797)/W(5780) is anticorrelated with R5495, a sign that extreme ζ clouds are characterized not only by low ionization environments (as opposed to σ clouds) but also by having a larger fraction of small dust grains. The equivalent width of the "Gaia DIB" (8621 Å) is strongly correlated with E(4405-5495), as expected, and its behavior appears to be more σ-like than ζ-like. We have also started analyzing some individual sightlines in detail.