Investigation of quantitative classification methods for early-type stars

1966 ◽  
Vol 24 ◽  
pp. 91-92
Author(s):  
U. Sinnerstad
Keyword(s):  
Absolute Magnitude ◽  
Classification Methods ◽  
Early Type ◽  
Quantitative Classification ◽  
Spectrophotometric Methods ◽  
Spectral Class ◽  
Dimensional Classification ◽  
Objective Prism ◽  
Early Type Stars ◽  
Low Dispersion

As is well known the spectrophotometric methods as introduced by B. Lindblad and developed at the Stockholm and Uppsala Observatories aim at relatively faint stars. The two-dimensional classification in terms of spectral class and absolute magnitude is based on spectrophotometric measures on objective-prism spectrograms of low dispersion (about 200Å/mm). The measures pertain to average intensities in bands having widths of about 30Å.

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.

Early-type stars in orthogonal halo fields. I - an objective-prism survey

1993 ◽  
Vol 106 ◽  
pp. 591 ◽  
Author(s):  
A. W. Rodgers ◽  
W. H. Roberts ◽  
I. Walker
Keyword(s):  
Early Type ◽  
Objective Prism ◽  
Early Type Stars

scholarly journals Intrinsic dispersion in early-type stars

1959 ◽  
Vol 10 ◽  
pp. 59-60
Author(s):  
Bengt Strömgren
Keyword(s):  
Two Dimensional ◽  
Early Type ◽  
Dimensional Classification ◽  
Basic Parameters ◽  
Early Type Stars

The principal basic parameters of early-type stars being mass and age, two-dimensional classification according to the MK system corresponds to a mass-age classification.

scholarly journals The Frequency of Faint M Giant Stars at High Galactic Latitudes

1977 ◽  
Vol 4 (2) ◽  
pp. 35-36 ◽  
Author(s):  
N. Sanduleak
Keyword(s):  
Main Sequence ◽  
Galactic Plane ◽  
Absolute Magnitude ◽  
Main Sequence Stars ◽  
Giant Stars ◽  
The North ◽  
Objective Prism ◽  
M Stars ◽  
Low Dispersion ◽  
North Galactic

Based on the observations of M giant stars in the north galactic polar objective-prism survey of Upgren (1960) and the data summarized by Blanco (1965) the overall space density of all M-type giants as a function of distance from the galactic plane at the position of the sun can be approximated by,where z is in kpc and ρ(z) is the number of stars per 106 pc3. This relationship is derived from the observed fall-off in space densities up to a distance of about 2 kpc.The question arises as to the validity of extrapolation equation (1) to larger z distances so as to predict the number of faint M giants expected per unit area near the galactic poles. Adopting for the M giants a mean visual absolute magnitude of −1.0 (Blanco 1965), one finds that equation (1) predicts that less than one giant fainter than V~12 should be expected in a region of 200 square degrees. This expectation formed the hypothesis of a thesis study (Sanduleak 1965) in which it was assumed that the very faint M stars detected in a deep, infrared objective-prism survey at the NGP were main-sequence stars, since this could not be ascertained spectroscopically on the very low-dispersion plates used.

scholarly journals Observations of Interstellar Reddening in Cygnus and Perseus

1965 ◽  
Vol 7 ◽  
pp. 17-25
Author(s):  
K Nandy
Keyword(s):  
Interstellar Extinction ◽  
The Other ◽  
Early Type ◽  
Schmidt Telescope ◽  
Present Survey ◽  
Amount Of Information ◽  
Royal Observatory ◽  
Objective Prism ◽  
Early Type Stars

The Object of the Edinburgh Spectrophotometry Survey is to determine the interstellar extinction law as precisely as possible and to search for intrinsic variations in it. The observations have been extended to early type stars up to a limiting magnitude of 11ṃ0 in regions extending from lII = 50° to lII = 200°. The 16/24/60-inch Schmidt telescope of the Royal Observatory has been used in conjunction with an objective prism and grating. Spectra extend from λ = 3300 Å to λ = 9000 Å with a dispersion of 1000 Å/mm at Hγ. Since few stars fainter than 9m have been measured in earlier investigations, the present survey extends considerably the amount of information available.In determining the extinction from a comparison of pairs of stars, one reddened and the other unreddened, one is faced by the problem of having to find two intrinsically similar stars in the same galactic region.

scholarly journals Tracing Large-Scale Structure with Galaxy Objective-Prism Spectra

1988 ◽  
Vol 130 ◽  
pp. 525-525
Author(s):  
Q.A. Parker ◽  
H.T. Macgillivray ◽  
S.M. Beard
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Early Type ◽  
Galaxy Distribution ◽  
Large Numbers ◽  
The Galaxy ◽  
Measured Sample ◽  
Objective Prism ◽  
Low Dispersion

A new and promising use of galaxy objective-prism spectra as a means of highlighting features in the large scale galaxy distribution has been recently reported by Parker et al. (1987). The technique relies on the property that galaxies with identifiable 4000Å features in low dispersion objective-prism spectra are mostly ellipticals (Cooke, 1980), and that early type galaxies seem to delineate structure and clumpiness in the galaxy distribution (e.g. Giovanelli and Haynes, 1982). The effect is most striking when large numbers of objective-prism galaxy spectra are considered. Figure 1 gives the X-Y plot for 1539 galaxies with 4000Å features to Bj=18.7 in one UKST field out of a manually measured sample of 2903 galaxy prism spectra. Substantial clumpiness is evident. This technique can trace structure in the galaxy distribution across many UKST fields to depths of 400 h−1Mpc.

scholarly journals Microphotometry-Computer Classification of Objective-Prism Spectra

1973 ◽  
Vol 50 ◽  
pp. 125-126
Author(s):  
K. M. Yoss
Keyword(s):  
Figure Of Merit ◽  
Three Dimensional ◽  
Absolute Magnitude ◽  
Calibration Data ◽  
Dimensional Classification ◽  
Straight Line ◽  
Objective Prism ◽  
Computer Classification ◽  
Right Ascension

Three-dimensional classification of late-type stars is obtained through computer-processed digitized microphotometer data. Plate transmissions are converted to relative intensity through spot-sensitometer calibration data. A pseudo-continuum consisting of several straight-line segments is formed by connecting high points in the spectrum. Absorption-line strengths and line ratios are then measured. The temperature-and-luminosity-sensitive ratios are relatively insensitive to seeing effects. For plates with a dispersion of 108 Å mm-1, preliminary results indicate an accuracy in derived absolute magnitude comparable to, and possibly better than, that of MK classification.The CN anomaly serves as the abundance index. The CN index was defined in a manner to give the largest figure of merit (the ratio of total range of the index to the mean error). The adopted method is the same as that of Yoss and Lutz (1971) and has a figure of merit over twice that of the index similar to that of Griffin and Redman (1960).For field stars, plate X and Y positions are converted to equatorial coordinates and printed out in order of increasing right ascension, making quick and easy identification of the Henry Draper numbers.

scholarly journals Ultraviolet Spectrophotometry of Early-Type Stars

1976 ◽  
Vol 72 ◽  
pp. 161-165 ◽  
Author(s):  
K. Nandy ◽  
G. I. Thompson ◽  
C. M. Humphries
Keyword(s):  
Classification Scheme ◽  
Narrow Band ◽  
Two Dimensional ◽  
Early Type ◽  
Ultraviolet Spectrophotometry ◽  
B Stars ◽  
Preliminary Results ◽  
Ultraviolet Spectra ◽  
Dimensional Classification ◽  
Early Type Stars

The ultraviolet spectra of B stars obtained with the sky scan telescope in the TD1 satellite have been used to obtain narrow-band magnitudes at several wavelengths. These photometric bands have an effective half-width of 100 Å. We have proposed a two-dimensional classification scheme based on ultraviolet colours, and some preliminary results are presented.

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