other query modes : |
Identifier query |
Coordinate query |
Criteria query |
Reference query |
Basic query |
Script submission |
TAP |
Output options |
Object types |
Help |
2000ApJ...531..776G - Astrophys. J., 531, 776-803 (2000/March-2)
A spectroscopic study of a large sample of Wolf-Rayet galaxies.
GUSEVA N.G., IZOTOV Y.I. and THUAN T.X.
Abstract (from CDS):
We derive the numbers of early WC (WCE) and late WN (WNL) stars from the luminosities of the red and blue bumps, and the number of O stars from the luminosity of the Hβ emission line. Additionally, we propose a new technique for deriving the numbers of WNL stars from the N III λ4512 and Si III λ4565 emission lines. This technique is potentially more precise than the blue-bump method because it does not suffer from contamination of WCE and early WN (WNE) stars and nebular gaseous emission.
It is found that the relative number of WR stars N(WR)/N(O+WR) decreases with decreasing metallicity, in agreement with predictions of evolutionary synthesis models. The relative number ratios N(WC)/N(WN) and the equivalent widths of the blue bump EW(λ4650) and of the red bump EW(λ5808) derived from observations are also in satisfactory agreement with theoretical predictions, except for the most metal-deficient WR galaxies. A possible source of disagreement is too low a line emission luminosity adopted for a single WCE star in low-metallicity models.
We assemble a sample of 30 H II regions with detected He II λ4686 nebular emission to analyze the possible connection of this emission with the hard UV radiation of the WR stars. The theoretical predictions satisfactorily reproduce the observed intensities and equivalent widths of the He II λ4686 nebular emission line. However, galaxies with nebular He II λ4686 emission do not always show WR emission. Therefore, in addition to the ionization of He+ in the H II region by WR stars, other mechanisms for the origin of He II λ4686 such as radiative shocks probably need to be invoked.
Abstract Copyright: ∼
Journal keyword(s): Galaxies: Abundances - Galaxies: Starburst - Galaxies: Stellar Content - ISM: H II Regions - Stars: Wolf-Rayet
CDS comments: T.8 : 1441+294 not identified
Simbad objects: 67
To bookmark this query, right click on this link: simbad:2000ApJ...531..776G and select 'bookmark this link' or equivalent in the popup menu