Dynamical modeling of long-period variable star atmospheres

Bowen, G. H.

doi:10.1086/166378

Cited by 497 publications

(565 citation statements)

References 0 publications

Supporting

Mentioning

541

Contrasting

Order By: Relevance

“…This model represented the maser clumps as LVG blocks with physical conditions drawn from a pulsating atmosphere model of a Mira variable (Bowen 1988). The pulsating atmosphere provides radial shock-waves, attenuating with increasing radius.…”

Section: Water Maser Theory and Modellingmentioning

confidence: 99%

The physics of water masers observable with ALMA and SOFIA: model predictions for evolved stars

Gray

Baudry

Richards

et al. 2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

We present the results of models that were designed to study all possible water maser transitions in the frequency range 0-1.91 THz, with particular emphasis on maser transitions that may be generated in evolved-star envelopes and observed with the ALMA and SOFIA telescopes. We used tens of thousands of radiative transfer models of both spin species of H 2 O, spanning a considerable parameter space in number density, kinetic temperature and dust temperature. Results, in the form of maser optical depths, have been summarized in a master table, Table 6. Maser transitions identified in these models were grouped according to loci of inverted regions in the density/kinetic temperature plane, a property clearly related to the dominant mode of pumping. A more detailed study of the effect of dust temperature on maser optical depth enabled us to divide the maser transitions into three groups: those with both collisional and radiative pumping schemes (22,96,209,321,325,395,941 and 1486 GHz), a much larger set that are predominantly radiatively pumped, and another large group with a predominantly collisional pump. The effect of accelerative and decelerative velocity shifts of up to 5 km s −1 was found to be generally modest, with the primary effect of reducing computed maser optical depths. More subtle asymmetric effects, dependent on line overlap, include maximum gains offset from zero shift by >1 km s −1 , but these effects were predominantly found under conditions of weak amplification. These models will allow astronomers to use multi-transition water maser observations to constrain physical conditions down to the size of individual masing clouds (size of a few astronomical units).

show abstract

Section: Water Maser Theory and Modellingmentioning

confidence: 99%

The physics of water masers observable with ALMA and SOFIA: model predictions for evolved stars

Gray

Baudry

Richards

et al. 2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

show abstract

“…The computational improvements can be inferred by comparing these results with the radial structures depicted e.g. in Bowen (1988, Fig. 6-8, calculated for similar initial conditions using a much simpler Lagrangian numerical scheme).…”

Section: Resultsmentioning

confidence: 96%

“…For the equation of state we assume a perfect gas law (7 = 5/3, /i = 1.3), the Rosseland mean of the gas opacity is set to the constant value of 10~4 g/cm 3 and the dust opacity is calculated by the simple formula given in Bowen (1988).…”

Section: Basic Physics and Numerical Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Dust Driven Winds from Pulsating Stars

Dorfi¹,

Feuchtinger²,

Höfner³

1993

International Astronomical Union Colloquium

View full text Add to dashboard Cite

The cool extended atmospheres of late type giants are sites where dust formation takes place. Radiation pressure on the dust grains is an important force for driving the slow but massive winds observed in such objects. Existing calculations of dust driven stellar winds (e.g. Bowen 1988, Fleischer et al. 1991) suffer from the fact that they include approximations at various levels for different parts of the problem like the hydrodynamics or the dust formation. Furthermore they do not include time-dependent radiative transfer.In order to overcome these insufficiencies we plan to calculate self-consistent models of dust driven winds with a full description of both the radiation hydrodynamics and the time-dependent dust formation. As a first step, however, we concentrate our investigations on the self-consistent description of the radiation hydrodynamics adopting only a simple description of the dust opacities.

show abstract

“…Part of the line was found to originate in near-photospheric circumstellar material slightly shifted in velocity relative to the photosphere. It had earlier been suggested that if H2 is produced by three-body recombination, the recombination would be so slow in the low densities in mira atmospheres that H would remain neutral (not associated) between shocks (Bowen 1988). However, these observations disclose that, after the passage of a pulsationally driven shock through the atmosphere, the H2 lines reappear almost as quickly as do CO and TiO lines, forcing the conclusion that recombination proceeds more rapidly than expected, which in turn demands higher densities of H I or consideration of processes other than three-body recombination.…”

Section: Hmentioning

confidence: 99%

Effects of Non-Local Thermodynamic Equilibrium (NLTE) on Molecular Opacities

Johnson

1994

International Astronomical Union Colloquium

View full text Add to dashboard Cite

Molecules increase in importance in stellar atmospheres as the temperature falls along the spectral sequence for all luminosity classes. Among their many roles molecular features provide the basis for spectral classification (temperature and chemical composition) in M, S, and C stars; they constitute important opacity sources across the spectrum from the ultraviolet to the infrared; they influence the energy budget and hence the kinetic temperature in the outer photospheric layers; they may contribute significantly to the radiative levitation of the atmosphere; they form masers; they may cause or facilitate mass loss; and they are indicative of physical conditions and processes from the photosphere to the outer circumstellar envelope.

show abstract

Dynamical modeling of long-period variable star atmospheres

Cited by 497 publications

References 0 publications

The physics of water masers observable with ALMA and SOFIA: model predictions for evolved stars

The physics of water masers observable with ALMA and SOFIA: model predictions for evolved stars

Dust Driven Winds from Pulsating Stars

Effects of Non-Local Thermodynamic Equilibrium (NLTE) on Molecular Opacities

Contact Info

Product

Resources

About