Pulsational Stability ofg‐Modes in Slowly Pulsating B Stars

2001 ◽  
Vol 557 (1) ◽  
pp. 311-319 ◽  
Author(s):  
Umin Lee
Keyword(s):  
B Stars ◽  
Pulsational Stability

scholarly journals Understanding Pulsations in OB Stars

2000 ◽  
Vol 176 ◽  
pp. 401-407
Author(s):  
L. A. Balona
Keyword(s):  
Spherical Harmonic ◽  
Instability Strip ◽  
B Stars ◽  
Ob Stars ◽  
Inhibiting Effect ◽  
Model Predictions ◽  
High Degree ◽  
Pulsational Stability ◽  
Good Agreement

AbstractOur understanding of pulsations in β Cep, SPB and ζ Oph stars is discussed. We do not understand why there are no β Cep stars earlier than O9, though the models show that the instability strip extends to hotter stars. The main problem among the SPB stars is why rotation has a strong inhibiting effect on pulsation. The ζ Oph stars are an extension of the β Cep and SPB stars to higher spherical harmonic degrees. The pulsational stability of models of B stars to modes of high degree is discussed. Results are compared with two well observed ζ Oph stars. Although there is good agreement with ζ Oph itself, the periods of the high-degree modes in α Vir are incompatible with model predictions.

A Theoretical Exploration of the Pulsational Stability of Subdwarf B Stars

2001 ◽  
Vol 113 (785) ◽  
pp. 775-788 ◽  
Author(s):  
Stéphane Charpinet ◽  
G. Fontaine ◽  
P. Brassard
Keyword(s):  
B Stars ◽  
Subdwarf B Stars ◽  
Pulsational Stability

Photo-electric Hβ and uvby photometry

1966 ◽  
Vol 24 ◽  
pp. 170-180
Author(s):  
D. L. Crawford
Keyword(s):  
Narrow Band ◽  
Line Strength ◽  
Interference Filter ◽  
B Stars ◽  
Relative Line ◽  
The Mean ◽  
F Stars ◽  
Two Parameters ◽  
Filter Photometry ◽  
The Continuum

Early in the 1950's Strömgren (1, 2, 3, 4, 5) introduced medium to narrow-band interference filter photometry at the McDonald Observatory. He used six interference filters to obtain two parameters of astrophysical interest. These parameters he calledlandc, for line and continuum hydrogen absorption. The first measured empirically the absorption line strength of Hβby means of a filter of half width 35Å centered on Hβand compared to the mean of two filters situated in the continuum near Hβ. The second index measured empirically the Balmer discontinuity by means of a filter situated below the Balmer discontinuity and two above it. He showed that these two indices could accurately predict the spectral type and luminosity of both B stars and A and F stars. He later derived (6) an indexmfrom the same filters. This index was a measure of the relative line blanketing near 4100Å compared to two filters above 4500Å. These three indices confirmed earlier work by many people, including Lindblad and Becker. References to this earlier work and to the systems discussed today can be found in Strömgren's article inBasic Astronomical Data(7).

Calibration problems in hydrogen luminosities

1966 ◽  
Vol 24 ◽  
pp. 322-330
Author(s):  
A. Beer
Keyword(s):  
Galactic Structure ◽  
B Stars ◽  
Insight Into

The investigations which I should like to summarize in this paper concern recent photo-electric luminosity determinations of O and B stars. Their final aim has been the derivation of new stellar distances, and some insight into certain patterns of galactic structure.

A Search for β Cephei Stars in the Southern Hemisphere - Results

1979 ◽  
Vol 46 ◽  
pp. 474-503 ◽  
Author(s):  
M. Jerzykiewicz ◽  
C. Sterken
Keyword(s):  
Southern Hemisphere ◽  
B Stars ◽  
Search Program

In 1975 we started a photometric search program of examining for variability- the bright early B stars located south of -20° declination. The main purpose we had in mind was to look for hitherto undiscovered 6 Cephei variables. Therefore, we limited our program to objects spectroscopically similar to the B Cephei stars.

Ultraviolet Spectral Classification of O and B Stars in the Large Magellanic Cloud

1999 ◽  
Vol 117 (6) ◽  
pp. 2856-2867 ◽  
Author(s):  
Margaret M. Smith Neubig ◽  
Frederick C. Bruhweiler
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Spectral Classification ◽  
B Stars

Boron Abundances of B Stars of the Orion Association

1997 ◽  
Vol 478 (1) ◽  
pp. 211-224 ◽  
Author(s):  
Katia Cunha ◽  
David L. Lambert ◽  
Michael Lemke ◽  
Douglas R. Gies ◽  
Lewis C. Roberts
Keyword(s):  
B Stars ◽  
Orion Association

scholarly journals UV Spectral Classification of B Stars

1985 ◽  
Vol 111 ◽  
pp. 411-413
Author(s):  
Janet Rountree ◽  
George Sonneborn ◽  
Robert J. Panek
Keyword(s):  
Classification System ◽  
Classification Criteria ◽  
High Dispersion ◽  
Spectral Classification ◽  
Early Type ◽  
B Stars ◽  
Dimensional Classification ◽  
Early Type Stars ◽  
Comprehensive Classification

Previous studies of ultraviolet spectral classification have been insufficient to establish a comprehensive classification system for ultraviolet spectra of early-type stars because of inadequate spectral resolution. We have initiated a new study of ultraviolet spectral classification of B stars using high-dispersion IUE archival data. High-dispersion SWP spectra of MK standards and other B stars are retrieved from the IUE archives and numerically degraded to a uniform resolution of 0.25 or 0.50 Å. The spectra (in the form of plots or photowrites) are then visually examined with the aim of setting up a two-dimensional classification matrix. We follow the method used to create the MK classification system for visual spectra. The purpose of this work is to examine the applicability of the MK system (and in particular, the set of standard stars) in the ultraviolet, and to establish classification criteria in this spectral region.

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