Sign on
ADS Classic is now deprecated. It will be completely retired in October 2019. Please redirect your searches to the new ADS modern form or the classic form. More info can be found on our blog.

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Full Refereed Journal Article (PDF/Postscript)
· Full Refereed Scanned Article (GIF)
· References in the article
· Citations to the Article (710) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (72)
· Also-Read Articles (Reads History)
· Translate This Page
The Lyman-Continuum Fluxes and Stellar Parameters of O and Early B-Type Stars
Vacca, William D.; Garmany, Catharine D.; Shull, J. Michael
Astrophysical Journal v.460, p.914 (ApJ Homepage)
Publication Date:
Astronomy Keywords:
Bibliographic Code:


Using the results of the most recent stellar atmosphere models applied to a sample of hot stars, we construct calibrations of effective temperature (Teff), and gravity (log g) with a spectral type and luminosity class for Galactic O-type and early B-type stars. From the model results we also derive an empirical relation between the bolometric correction and Teff and log g. Using a sample of stars with known distances located in OB associations in the Galaxy and the Large Magellanic Cloud, we derive a new calibration of Mupsilo with spectral class. With these new calibrations and the stellar atmosphere models of Kurucz, we calculate the physical parameters and ionizing photon luminosities in the H0 and He0 continua for O and early B-type stars. We find substantial differences between our values of the Lyman- continuum luminosity and those reported in the literature. We also discuss the systematic discrepancy between O-type stellar masses derived from spectroscopic models and those derived from evolutionary tracks. Most likely, the cause of this "mass discrepancy" lies primarily in the atmospheric models, which are plane parallel and hydrostatic and therefore do not account for an extended atmosphere and the velocity fields in a stellar wind. Finally, we present a new computation of the Lyman-continuum luminosity from 429 known O stars located within 2.5 kpc of the Sun. We find the total ionizing luminosity from this population (Q0Tot = 7.0 × 1051 photons s-1) to be 47% larger than that determined using the Lyman continuum values tabulated by Panagia.

Printing Options

Print whole paper
Print Page(s) through

Return 600 dpi PDF to Acrobat/Browser. Different resolutions (200 or 600 dpi), formats (Postscript, PDF, etc), page sizes (US Letter, European A4, etc), and compression (gzip,compress,none) can be set through the Printing Preferences

More Article Retrieval Options

HELP for Article Retrieval

Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)

Find Similar Abstracts:

Use: Authors
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
arXiv e-prints