scholarly journals The Galactic Distribution of OH/IR Stars

1977 ◽  
Vol 42 ◽  
pp. 399-433
Author(s):  
H.J. Habing
Keyword(s):  
Present Status ◽  
Line Emission ◽  
Microwave Line ◽  
Late Type ◽  
Maser Emission ◽  
Long Period ◽  
Ir Stars ◽  
Long Period Variables ◽  
Recent Compilation ◽  
Galactic Distribution

In 1967 Wilson and Barrett (1968, 1970) discovered that some long period variables, very red and apparently very late type stars, emit OH microwave line emission that is especially strong in the 1612 MHz line at 18 cm. At present some 65 such OH-emitting stars have been identified - for a recent compilation see Bowers and Kerr (1977, M giants) and Baudry et al. (1977, M supergiants). Several stars show maser emission in H2O and SiO as well. At this colloquium Winnberg will review the present status of our knowledge of these stars.

scholarly journals The galactic distribution of OH/IR stars

1979 ◽  
Vol 84 ◽  
pp. 29-34
Author(s):  
B. Baud ◽  
H. J. Habing ◽  
J. H. Oort
Keyword(s):  
Spectral Type ◽  
Velocity Difference ◽  
Double Peak ◽  
Strong Emission ◽  
Long Period ◽  
Ir Stars ◽  
Long Period Variables ◽  
Galactic Distribution

Through systematic surveys (Johansson et al., Caswell and Haynes, Bowers, Baud, Caswell et al.) some 200 OH masers have been detected that are presumably associated with long period variables of very late spectral type (>M5). Tentatively these stars will be called “OH/IR stars”. They are characterized by their strong emission in the 1612 MHz line which shows a double peak due to the expansion of the shell surrounding these stars. The velocity difference ΔV between the peaks is generally between 10 and 50 km s−1.

scholarly journals Variability study of the FBS M giants

2021 ◽  
pp. 478-483
Author(s):  
K. S. Gigoyan ◽  
G. R. Kostandyan
Keyword(s):  
Light Curves ◽  
Late Type ◽  
Data Bases ◽  
Byurakan Survey ◽  
Distance Information ◽  
Long Period ◽  
Sky Survey ◽  
Variability Study ◽  
Variability Data ◽  
Galactic Distribution

We study in this paper variability of the late-type M giants found in the First Byurakan Survey (FBS) spectroscopic data base. We used phase dependent light – curves from large sky area variability data bases such as Catalina Sky Survey (CSS) and All-Sky Automated Survey for Supernovae (ASAS-SN). We used also the distance information derived from Gaia EDR3 to construct the Galactic distribution of the M – type giants from the second edition of the FBS Late-Type Stars catalogue including various kinds of long period variables.

Some Dependences for Long-Period Variables and a Possible Scheme of their Evolution

1989 ◽  
Vol 131 ◽  
pp. 451-451
Author(s):  
I. L. Andronov ◽  
L. S. Kudashkina ◽  
G. M. Rudnitskij
Keyword(s):  
Light Curve ◽  
Color Index ◽  
Variable Stars ◽  
Maser Emission ◽  
Long Period ◽  
General Catalogue ◽  
Long Period Variables ◽  
Molecular Lines ◽  
Visual Light

Some dependences between the parameters for approximately 150 stars, of which 81 are sources of maser emission in molecular lines, are constructed. The following parameters are considered: period P, asymmetry (M-m) of the visual light curve, visual amplitude A, color index (I-K). We use the data of the General Catalogue of Variable Stars. For the stars Z Cyg, R Tau, R Peg, RT Vir, RX Boo, PZ Cas, U Her, and R Cas, some parameters were determined by the authors.

The Galactic Distribution and Kinematics of OH Stars (A Preliminary Discussion)

1975 ◽  
Vol 2 (6) ◽  
pp. 362-363
Author(s):  
P.F. Bowers
Keyword(s):  
Large Scale ◽  
Velocity Dispersion ◽  
Neutral Hydrogen ◽  
Late Type ◽  
Velocity Range ◽  
Hydrogen Distribution ◽  
Mira Variables ◽  
Sky Survey ◽  
Ir Stars ◽  
Galactic Distribution

The majority of OH/IR stars have been identified as M-type Mira variables, but there are a few cases where the stars have been identified as M supergiants or late-type semi-regular variables. A large number of OH sources have also been discovered with the 1612 MHz OH characteristics of OH/IR stars but no apparent optical or infrared counterparts. In several cases the velocities of these unidentified sources (OH stars) have been outside the velocity range of the neutral hydrogen distribution, suggesting that some of these sources may represent a population with a higher velocity dispersion than Population I objects (Kerr and Bowers 1974a, b). The lack of infrared and optical counterparts may indicate that the sources are quite distant, since identified OH/IR stars are often bright infrared objects. A large-scale 1612 MHz sky survey has therefore been initiated to study the galactic distribution and kinematics of the OH stars and to investigate the possibility that they may represent an older population of stars (Bowers et al. 1974).

Spectroscopy and Narrow Band Polarimetry of Red Long Period Variables

1979 ◽  
Vol 46 ◽  
pp. 280-283
Author(s):  
A.M. Magalhães ◽  
S.J. Codina - Landaberry ◽  
G.V. Coyne
Keyword(s):  
Narrow Band ◽  
Spectral Features ◽  
Late Type ◽  
Intrinsic Polarization ◽  
Long Period ◽  
Long Period Variables ◽  
Balmer Lines

AbstractA set of narrow band filters for studying variations in the intrinsic polarization across spectral features in late type variables stars is presented. The primary purpose is to study TiO bands and Hydrogen Balmer lines in the spectrum of such variables. These observations should help in distinguishing the role of the various sources of polarization in the extended atmospheres of the Mira and Semi-regular variables.

scholarly journals On the Possible Relationship Between the Photometric Parameters of the AGB Stars and Their Evolutionary Status

1993 ◽  
Vol 155 ◽  
pp. 324-324
Author(s):  
L.S. Kudashkina ◽  
I.L. Andronov
Keyword(s):  
Shock Wave ◽  
Light Curve ◽  
Statistical Study ◽  
Line Emission ◽  
Evolutionary Status ◽  
Evolutionary Stage ◽  
Agb Stars ◽  
Long Period ◽  
Long Period Variables ◽  
Period Variable

The statistical study of the Long-Period Variables, provided by various authors, show, that there is a relationship between the photometric characteristics and the physical properties. For example, the asymmetry of the light curve may be related with the strength of the shock wave. The presence of the maser-fed line emission characterizes the definite evolutionary stage of the Long-Period Variable.

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