scholarly journals Report of the Committee on the Spectra of Variable Stars

1970 ◽  
Vol 14 (1) ◽  
pp. 286-291
Author(s):  
M. W. Feast
Keyword(s):  
Binary Systems ◽  
Absolute Magnitude ◽  
Variable Stars ◽  
Extensive Study ◽  
High Dispersion ◽  
Fundamental Parameter ◽  
Long Period ◽  
Mira Variables ◽  
The Difference

The field covered by this report overlaps particularly with the work of Commissions 29 and 45 whose reports should be consulted. I have been greatly helped by reports on Soviet work by Professor Kukarkin and Dr Boyarchuk and a bibliography of European literature by Bloch.The Sonneberg programme for determining spectral types of variables has been described by Götz and Wenzel (AN, 290, 99) and several lists have been published in MVS. Bakos is studying high dispersion spectra of a number of variables that are members of visual binary systems.Stephenson and Terrill (ApJ, 147, 148) and Houk (IB, 228) have given spectral types for a considerable number of long period variables. Terrill (AJ, 74, 413) has made an extensive study of the variation of spectrum with phase for 51 red variables. Deutsch, Keenan and Garrison have continued their extensive programme of spectral classification of Mira variables. Keenan and Dessy (ApJ, 146, 583) suggest that the relatively early spectral type of the very long period Miras (R Cen, R Nor etc.) showing double maxima indicates that the fundamental parameter is the half-period (between successive maxima). A similar conclusion (ApJ, 93, 380; MN, 125, 367) was reached earlier by others on the basis of the correlation with period of the difference between absorption and emission velocities. Feast has used K subgiant companion of U Men to derive an absolute magnitude of — 0m.5 for the Mira star. The radial velocity of the companion agrees with the absorption velocity of the variable near maximum (Obs.).

scholarly journals Comparison of Mean Light Curve Parameters of M, S and C Mira and Semi-Regular Variable Stars Using 75 Years of AAVSO Data

2000 ◽  
Vol 177 ◽  
pp. 165-170
Author(s):  
Marie-Odile Mennessier ◽  
Hichame Boughaleb ◽  
Janet A. Mattei
Keyword(s):  
Light Curve ◽  
Variable Stars ◽  
Light Curves ◽  
Long Period ◽  
Regular Variable

Using 75 years of AAVSO data, mean light curve parameters of a sample of 350 long-period M, S and C Mira and semi-regular variable stars have been investigated. We compare M, S and C Mira and semi-regular stars, present a classification of the light curves of LPVs and give discriminant parameters.

scholarly journals Verification of the Spectral Classification of Stars Using the Hipparcos Catalogue

2014 ◽  
Vol 31 ◽  
Author(s):  
D. Deb ◽  
P. Chakraborty
Keyword(s):  
Absolute Magnitude ◽  
Interstellar Extinction ◽  
Statistical Technique ◽  
The Other ◽  
Spectral Classification ◽  
Intrinsic Nature ◽  
Hipparcos Catalogue ◽  
The Difference ◽  
Rule Out

AbstractThe spectral classifications of the stars from spectral data have been corrected from time to time and new spectral and luminosity classes have been assigned. Identifying stars with wrong spectral and luminosity classification has been a stupendous task from the huge catalogue of stars. In this work we describe a simple statistical technique to identify stars with wrong spectral and luminosity classification. We make use of the Hipparcos catalogue which has the most accurate measurement of the distance d of the stars. A comparison is made between the absolute V magnitudes MV computed using the observed V magnitude mV and d, with the standard absolute magnitude MV0 assigned to a spectral and luminosity classification for a large number of stars (with d < 100 pc). As expected, for most of the stars the difference between MV and MV0 lies within the range ±2 mag, due to the intrinsic nature of each star ignored in this generalisation. A systematic error analysis is made of all the observable used in the computation. Therefore to identify stars which we suspect to be wrongly classified, we look for abnormal deviation in |MV – MV0| ≥5. The location of these stars with respect to the galactic plain and interstellar extinction is also investigated to rule out effects due to variations in the interstellar extinction. From our results we see that some of the stars were indeed wrongly classified and have recently been reclassified (SIMBAD). The reclassification drastically reduces the |MV – MV0| deviation. The other stars in the list which have not yet been reclassified need to be spectroscopically investigated and classified again.

scholarly journals Physics and Evolution of LPVs from HIPPARCOS Kinematics

1999 ◽  
Vol 191 ◽  
pp. 117-122 ◽  
Author(s):  
M.O. Mennessier ◽  
R. Alvarez ◽  
X. Luri ◽  
M. Noirhomme-Fraiture ◽  
E. Rouard
Keyword(s):  
Variable Stars ◽  
Light Curves ◽  
Astronomical Data ◽  
Long Period ◽  
Period Variable

The HIPPARCOS satellite provides astronomical data for about one thousand Long Period Variable stars (LPVs) from which kinematics properties and luminosity calibrations in several bandpasses are deduced using an appropriate method. Several results are deduced: a classification of the LPVs and its relation with the classification from the light curves, a calibration of luminosities inducing properties (age, mass, etc.) along the AGB and a comparison of oxygen to carbon-rich stars.

scholarly journals Optical and Near-IR Monitoring of Symbiotic Binary Systems

2001 ◽  
Vol 183 ◽  
pp. 167-176
Author(s):  
Joanna Mikołajewska
Keyword(s):  
Binary Systems ◽  
Variable Stars ◽  
Type Star ◽  
Symbiotic Stars ◽  
Future Prospects ◽  
Dust Shell ◽  
Giant Star ◽  
Long Period ◽  
Near Ir ◽  
Red Giant

AbstractSymbiotic stars are long-period interacting binary systems in which an evolved red giant star transfers material to its much hotter compact companion. Such a composition places them among the most variable stars. In addition to periodic variations due to the binary motion, they often show irregular changes due to nova-like eruptions of the hot component. In some systems the cool giant is a pulsating Mira-type star usually surrounded by a variable dust shell. Here, I present results of optical and IR monitoring of symbiotic systems as well as future prospects for such studies.

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