scholarly journals Classification of Early Type Stars on the Dominion Astrophysical Observatory Photometric System

1973 ◽  
Vol 50 ◽  
pp. 152-161
Author(s):  
S. C. Morris ◽  
G. Hill ◽  
G. A. H. Walker ◽  
H. I. B. Thompson
Keyword(s):  
Classification Method ◽  
Photometric System ◽  
Early Type ◽  
Balmer Series ◽  
Early Type Stars ◽  
Independent Parameters

A classification method has been developed for early–type stars observed on the Dominion Astrophysical Observatory photometric system. Two reddening-independent parameters, Q(35) and Q(38), are used. Q(35) is a measure of the Balmer discontinuity, while Q(38) is a measure of the strength of the upper members of the Balmer series. A preliminary calibration of Q(35) and Q(38) in terms of spectral types and luminosity classes is given, and applications to several groups of stars are shown.

scholarly journals Two Dimensional Spectral Classification of Early Type Stars by Narrow Band Photometry

1979 ◽  
Vol 47 ◽  
pp. 507-518
Author(s):  
M. Gerbaldi ◽  
N. Morguleff
Keyword(s):  
Narrow Band ◽  
Statistical Technique ◽  
Photometric System ◽  
Two Dimensional ◽  
Spectral Classification ◽  
Early Type ◽  
Early Type Stars ◽  
Independent Parameters ◽  
Best Parameters

AbstractSpectrophotometry data of 775 early type stars in a narrow band photometric system are analyzed, looking for the best parameters for a two dimensional spectral classification in the spectral region 3575 Å - 6000 Å. A correlation is established with the MK classification. The statistical technique of Principal Componant Analysis is applied to determine the number of linearly independent parameters among the data.

scholarly journals Spectral Classification of Early Type Stars from the Low Dispersion Ultraviolet Spectra

1977 ◽  
Vol 4 (2) ◽  
pp. 289-301 ◽  
Author(s):  
K. Nandy
Keyword(s):  
Spectral Type ◽  
Main Sequence ◽  
Photometric System ◽  
Spectral Classification ◽  
Early Type ◽  
Ultraviolet Spectra ◽  
Early Type Stars ◽  
Natural Groups ◽  
Low Dispersion

The methods of spectral classification from the low dispersion ultraviolet spectra obtained with the S2/68 experiment in the TD1 satellite have been described. The bright stars, the spectra of which are photometrically accurate, can be divided into natural groups according to the spectral appearance of the features. These features vary in strength with spectral type and luminosity, and enable separation between main sequence and luminous stars. The limits for these stars areat BO toat AO. For fainter stars the spectral data have been combined to obtain narrow band magnitudes at several wavelengths. These photometric bands have an effective width of 100 A. An ultraviolet photometric system which enables determinations of spectral type and luminosity of early type stars is described and the results for about 3000 stars is presented. The photometric system considered here consists of the ultraviolet colour indices (m2740−V,) (m2190−V) and (m1490−V).

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.

scholarly journals Some Physical Parameters and UVBY β Photometry of Trapezium Type Multiple Systems

1995 ◽  
Vol 166 ◽  
pp. 391-391
Author(s):  
G.N. Salukvadze ◽  
G. Sh. Javakhishvili
Keyword(s):  
Photon Counting ◽  
Physical Parameters ◽  
Photometric System ◽  
Early Type ◽  
Multiple Systems ◽  
Early Type Stars ◽  
Absolute Magnitudes ◽  
Bolometric Correction ◽  
Semi Empirical ◽  
Mirror Telescope

The presented paper deals with the results of electrophotometric observations of 59 components of 19 trapezia in Strömgren and Crawford six-colour photometric system. The multiple systems, selected from the Abastumani Catalogue of Trapezia (Salukvadze, 1978), are: ABAO 2, 8, 34, 48, 51, 62, 75, 94, 245, 312, 313, 316, 324, 348, 356, 363, 387, 396.Observations were made on the 125-cm mirror telescope with the use of a one-channel photometer, based on photon counting, with diaphragms 10″ and 20″. Reduction was done on the Observatory computer with a procedure described by Salukvadze and Javakhishvili (1989).We calculated the indices [m1],[c1] and [u-b] as in (Strömgren 1967, Philip and Egret 1980). The unreddened indices (b-y), m1 and c1 were calculated by the formulae of Crawford (1975).Semi-empirical calibrations for effective temperature, bolometric correction and mass for early-type stars, using Strömgren photometric indices c0 and beta, are given by Balona (1984). In order to determine absolute magnitudes we used the calibration from Balona and Shobbrook (1984).

scholarly journals The Zero-Point of the Cepheid Luminosity Scale from a Calibration of the Luminosities of Early-Type Stars

1985 ◽  
Vol 82 ◽  
pp. 201-202
Author(s):  
L. A. Balona ◽  
R. R. Shobbrook
Keyword(s):  
Zero Point ◽  
Photometric System ◽  
Early Type ◽  
Early Type Stars ◽  
The Absolute ◽  
Absolute Magnitudes ◽  
Zero Points

AbstractA new calibration of the absolute magnitudes of early-type stars in terms of the (β, c0) photometric system is used to establish the distance moduli of clusters containing Cepheids. The zero points of the period – luminosity and period – luminosity – colour relations are calculated and compared to previous determinations.

scholarly journals The Estimation of the Electron Density ne with a Narrow-Band Photometric System Calibrated by Model Atmospheres

1985 ◽  
Vol 111 ◽  
pp. 557-560
Author(s):  
M. Gerbaldi ◽  
N. Morguleff
Keyword(s):  
Electron Density ◽  
Narrow Band ◽  
Photometric System ◽  
Early Type ◽  
Peculiar Stars ◽  
Early Type Stars ◽  
Definition Of

A spectrophotometer was originally designed by Barbier (1960) for the study of early-type stars. The band passes were chosen to measure the features of the hydrogen spectrum. To the first definition of the system (Barbier and Morguleff 1964), two more bands were added, specifically devoted to the peculiar stars of type Ap and Am (Gerbaldi 1972). The interpretation of these observations has already been given separately. We will concentrate here on the calibration of this spectrophotometric system in terms of Teff, log g and electron density ne.

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