Stability analysis, non-linear pulsations and mass loss of models for 55 Cygni (HD 198478)

55 Cygni is a variable supergiant. Recent observational studies revealed that this star pulsates in pressure, gravity and strange modes. The pulsations seem to be associated with episodes of mass loss. In this paper we present a theoretical study of stellar models with parameters close to that of 55...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2016-04, Vol.457 (4), p.4330-4339
Main Authors: Yadav, Abhay Pratap, Glatzel, Wolfgang
Format: Article
Language:English
Subjects:
Computer simulation
Gravity
Instability
Mathematical models
Nonlinearity
Pressure
Pulsars
Pulsation
Simulation
Stability
Stability analysis
Star & galaxy formation
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Summary:55 Cygni is a variable supergiant. Recent observational studies revealed that this star pulsates in pressure, gravity and strange modes. The pulsations seem to be associated with episodes of mass loss. In this paper we present a theoretical study of stellar models with parameters close to that of 55 Cygni. A linear non-adiabatic stability analysis with respect to radial perturbations is performed and the evolution of instabilities into the non-linear regime is followed by numerical simulation. Our study indicates that the mass of 55 Cygni lies below 28 M⊙. As the final consequence of the instabilities the non-linear simulations revealed finite amplitude pulsations with periods consistent with the observations. The non-linear results also indicate a connection between pulsations and mass loss and allow for an estimate of the mean mass-loss rate. It is consistent with the observed values.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stw236