Pumping of main line OH masers in the circumstellar envelopes of Type I Mira variables

1993 ◽  
Vol 413 ◽  
pp. 735 ◽  
Author(s):  
Alan J. Collison ◽  
Gerald Nedoluha
Keyword(s):  
Main Line ◽  
Type I ◽  
Circumstellar Envelopes ◽  
Mira Variables

scholarly journals Constraints for Cataclysmic Binary Evolution as Derived from Space Distributions

1984 ◽  
Vol 80 ◽  
pp. 363-385
Author(s):  
H. W. Duerbeck
Keyword(s):  
Stellar Populations ◽  
Recurrence Time ◽  
Type I ◽  
Symbiotic Stars ◽  
Late Type ◽  
Dwarf Novae ◽  
Space Density ◽  
Long Period ◽  
Mira Variables ◽  
Cataclysmic Binaries

AbstractSpace densities and galactic z-distributions of novae, recurrent novae, dwarf novae and symbiotic stars are newly determined and discussed in the context of earlier determinations. The data are then compared with the distributions of single and binary stars of possibly related types (late type giants, Mira variables, Algol systems, W UMa systems).Novae and dwarf novae have similar distributions, those of fairly young stellar populations. The observed space density of potential novae (novalike objects) indicates that the mean recurrence time of novae might be as small as a few hundred years, which leads, with given nova shell masses and mass transfer rates in the minimum stage, to a secular decrease of the masses of the components undergoing nova outbursts.Recurrent novae and symbiotic stars have distributions of older stellar populations, similar to those of late type giants and Mira variables.On the basis of galactic distribution, novae and dwarf novae are closely related and may be final stages of W UMa systems, as well as progenitors of supernovae of type I. A small fraction of W UMa systems seems to belong to an older population. If evolutionary transitions between these types of stars can be substantiated, the presence of a minority of novae and dwarf novae in globular clusters and of supernovae I in elliptical galaxies can be explained.Due to the lack of sufficiently well determined space distributions of Algol binaries, the suggestion that long-period Algol systems might be the progenitors of cataclysmic binaries can as yet neither be substantiated nor refuted. A very high space density of long-period Algol systems in the solar neighbourhood is derived. The observed space density of cataclysmic binaries could be explained by the transformation of a small percentage of the long-period Algol systems by common envelope evolution.

scholarly journals Radio Observations of Mira Variables, OH/IR Stars and M-Supergiants

1995 ◽  
Vol 155 ◽  
pp. 113-126
Author(s):  
Jessica M. Chapman ◽  
H. J. Habing ◽  
N. E. B. Killeen
Keyword(s):  
Circumstellar Envelopes ◽  
Radio Observations ◽  
Mira Variables ◽  
Ir Stars

AbstractWe review radio maser observations of the circumstellar envelopes of oxygen-rich Mira variables, OH/IR stars and M-type supergiants.

Mid-IR spectra of the M-type Mira variable R Tri observed with the Spitzer IRS

2020 ◽  
Vol 493 (1) ◽  
pp. 807-814
Author(s):  
Dana K Baylis-Aguirre ◽  
M J Creech-Eakman ◽  
Tina Güth
Keyword(s):  
Ir Spectra ◽  
Emission Feature ◽  
Absorption Feature ◽  
Cool Temperature ◽  
Circumstellar Envelopes ◽  
Mira Variables ◽  
Mira Variable ◽  
Molecular Lines ◽  
Infrared Spectrometer ◽  
Vibrational Bands

ABSTRACT We present analysis of mid-infrared (IR) spectra of the oxygen-rich Mira variable R Tri. The data were taken with the Spitzer Infrared Spectrometer (IRS) as part of a study tracking how Mira variables’ regular pulsations affect circumstellar envelopes. We detected strong emission lines at 13.87, 16.18, and 17.6 $\hbox{$\mu $m}$, and one strong absorption feature at 14.98 $\hbox{$\mu $m}$. The emission features at 13.87 and 16.18 $\hbox{$\mu $m}$ are excited vibrational bands of CO2, while the absorption feature is the fundamental ν2 band. The 17.6 $\hbox{$\mu $m}$ emission feature has a completely different character than the molecular lines and we report its identification as Fe i fluorescence. We used a two-slab model with the radiative transfer code radex to model the CO2 Q-branch bandheads. Our results indicate a slab of gas with T∼600 K located at ∼3–4 R*. The cool temperature discrepancy with the radius provides observational evidence for the previously theoretical ‘refrigeration zone’.

scholarly journals The OH Circumstellar Maser in Late-Type Stars

1980 ◽  
Vol 87 ◽  
pp. 549-550 ◽  
Author(s):  
Nguyen-Q-Rieu ◽  
V. Bujarrabal ◽  
J. Guibert ◽  
A. Omont
Keyword(s):  
Colour Index ◽  
Type I ◽  
The Sun ◽  
Type Ii ◽  
Late Type ◽  
Dust Shell ◽  
Ir Sources ◽  
Mira Variables

A recent investigation based upon the OH luminosity distribution (Nguyen-Q-Rieu et al. 1979) has shown that Type I OH sources associated with Mira variables (OH Miras) are weak OH sources and are therefore only detected within ∼1 kpc from the Sun. Type II OH-Miras, which are more intense and rarer than Type I OH-Miras, are probably more distant objects. The group of unidentified Type II OH-IR sources probably consists of Type II OH-Miras of high OH luminosity. The IR colour index, which is usually higher for Type II sources, suggests that they have a colder and denser dust shell.

Pumping of main line masers in type I Miras

2008 ◽  
pp. 361-364
Author(s):  
Alan J. Collison ◽  
Gerald E. Nedoluha
Keyword(s):  
Main Line ◽  
Type I

Variability of water masers in evolved stars on timescales of decades

2017 ◽  
Vol 13 (S336) ◽  
pp. 393-394 ◽  
Author(s):  
Jan Brand ◽  
Dieter Engels ◽  
Anders Winnberg
Keyword(s):  
Structural Changes ◽  
Circumstellar Envelopes ◽  
Evolved Stars ◽  
Mira Variables ◽  
Velocity Gradients ◽  
Systemic Velocity ◽  
Secular Variations ◽  
Red Supergiants ◽  
Water Masers

AbstractFor several decades (1987-2015) we have been carrying out observations of water masers in the circumstellar envelopes (CSE’s) of Mira variables, Red Supergiants (RSG’s) and Semi-Regular Variables (SRV’s) with the Medicina 32-m and Effelsberg 100-m antennas. The single-dish monitoring observations provide evidence for strong H2O maser profile variations, which likely are connected to structural changes in the maser shells. Such variations include strong flares in intensity lasting several (tens of) months and systemic velocity gradients of maser components developing over years, as well as other secular variations which are superimposed on periodic variations following the stellar light variations.When complemented with interferometric observations, it is possible to derive the 3-D distribution of the maser spots, and their lifetime, as we have done for RX Boo (Winnberget al.2008) and U Her (Winnberget al.2011; Brandet al. in prep.).

scholarly journals Submillimetre water masers at 437, 439, 471, and 474 GHz towards evolved stars

2020 ◽  
Vol 638 ◽  
pp. A19
Author(s):  
P. Bergman ◽  
E. M. L. Humphreys
Keyword(s):  
Radiative Transfer ◽  
Kinetic Temperature ◽  
Circumstellar Envelopes ◽  
Maser Emission ◽  
Evolved Stars ◽  
Mira Variables ◽  
Dust Temperature ◽  
Stellar Velocity ◽  
Maser Line ◽  
Water Masers

Aims. Here we aim to characterise submillimetre water masers at 437, 439, 471, and 474 GHz towards a sample of evolved stars. Methods. We used the Atacama Pathfinder Experiment (APEX1) to observe submillimetre water transitions and the CO (4–3) line towards 11 evolved stars. The sample included semi-regular and Mira variables, plus a red supergiant star. We performed radiative transfer modelling for the water masers. We also used the CO observations to determine mass loss rates for the stars. Results. From the sample of 11 evolved stars, 7 display one or more of the masers at 437, 439, 471, and 474 GHz. We therefore find that these masers are common in evolved star circumstellar envelopes. The fact that the maser lines are detected near the stellar velocity indicates that they are likely to originate from the inner circumstellar envelopes of our targets. We tentatively link the presence of masers to the degree of variability of the target star, that is, masers are more likely to be present in Mira variables than in semi-regular variables. We suggest that this indicates the importance of strong shocks in creating the necessary conditions for the masers. Typically, the 437 GHz line is the strongest maser line observed among those studied here. We cannot reproduce the above finding in our radiative transfer models. In general, we find that maser emission is very sensitive to dust temperature in the lines studied here. To produce strong maser emission, the dust temperature must be significantly lower than the gas kinetic temperature. In addition to running grids of models in order to determine the optimum physical conditions for strong masers in these lines, we performed smooth wind modelling for which we cannot reproduce the observed line shapes. This also suggests that the masers must originate predominantly from the inner envelopes.

scholarly journals TYPE I SUPERLUMINOUS SUPERNOVAE AS EXPLOSIONS INSIDE NON-HYDROGEN CIRCUMSTELLAR ENVELOPES

2016 ◽  
Vol 829 (1) ◽  
pp. 17 ◽  
Author(s):  
Elena Sorokina ◽  
Sergei Blinnikov ◽  
Ken’ichi Nomoto ◽  
Robert Quimby ◽  
Alexey Tolstov
Keyword(s):  
Type I ◽  
Circumstellar Envelopes
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