• Title of article

    On the calibration of the COBE/IRAS dust emission reddening maps

  • Author/Authors

    Claria، J. J. نويسنده , , Ahumada، A. V. نويسنده , , Bica، E. نويسنده , , Dutra، C. M. نويسنده , , Barbuy، B. نويسنده ,

  • Issue Information
    روزنامه با شماره پیاپی سال 2003
  • Pages
    -286
  • From page
    287
  • To page
    0
  • Abstract
    High resolution line profiles are presented for selected forbidden and permitted emission lines of a sample of galactic B[e]-type stars. The spectral resolution corresponds to 5-7 km s^-1 with the exception of some line profiles which were observed with a resolution of 9 -13 km s^-1. All H (alpha) profiles are characterized by a narrow split or single emission component with a width of ~ 150-250 km s^-1 (FWHM) and broad wings with a full width of ~ 1000-2000 km s^-1. The H (alpha) profiles can be classified into three groups: doublepeaked profiles representing the majority, single-peaked emission-line profiles, and normal P Cygni-type profiles. Likewise, the forbidden lines exhibit in most cases double-peaked profiles. In particular, the majority of stars shows split [O I] (lambda)6300 (ANGSTROM). Double-peaked profiles are also found in several stars for [N II] (lambda) 6583 (ANGSTROM) and [Fe II] (lambda) 7155 (ANGSTROM) although these lines in many stars exhibit single-peaked emission profiles. The split forbidden line profiles have peak separations of as little as ~10 km s^-1, and were therefore only discernible for the first time in the high-resolution spectra. The ratio of violet to red emission peak intensities, V/R, is predominantly smaller or equal to 1. Theoretical profiles were calculated for the optically thin case. A latitude-dependent stellar wind with a radial expansion and a velocity decreasing from the pole to the equator was adopted. This configuration can produce split line profiles if viewed under some angle with respect to the line of sight. In addition an equatorial dust ring with various optical depths was assumed. It can explain line asymmetries observed in some stars. Moreover, the V/R ratios can be understood in terms of this model. The comparison of the observed line profiles with the models thus confirms the assumption of disklike line-formation regions as commonly adopted for B[e]-type stars.
  • Keywords
    Galaxy: general , ISM: dust extinction , galaxies: ISM
  • Journal title
    Astronomy and Astrophysics
  • Serial Year
    2003
  • Journal title
    Astronomy and Astrophysics
  • Record number

    77032