scholarly journals Metastable Helium Absorptions with 3D Hydrodynamics and Self-consistent Photochemistry. II. WASP-107b, Stellar Wind, Radiation Pressure, and Shear Instability

2021 ◽  
Vol 914 (2) ◽  
pp. 99
Author(s):  
Lile Wang ◽  
Fei Dai
Keyword(s):  
Radiation Pressure ◽  
Stellar Wind ◽  
Shear Instability ◽  
Metastable Helium ◽  
Self Consistent

scholarly journals The domain of radiatively driven mass loss in the H-R diagram

1979 ◽  
Vol 83 ◽  
pp. 235-240 ◽  
Author(s):  
David C. Abbott
Keyword(s):  
Steady State ◽  
Mass Loss ◽  
Radiation Pressure ◽  
Effective Temperature ◽  
Stellar Wind ◽  
Radiation Force ◽  
Theoretical Uncertainty ◽  
Line Radiation ◽  
Consistent Model ◽  
Self Consistent

Previous work by Castor, Abbott, and Klein (1975) presented a self-consistent model of a steady-state stellar wind. They also showed qualitatively that for O stars at least a static atmosphere could not exist. This paper extends that result by calculating in detail the minimum luminosity as a function of effective temperature required for the line radiation force to exceed gravity. Within the observational and theoretical uncertainty there is a one-to-one correspondence between a star's calculated ability to self-initiate a stellar wind by radiation pressure alone and the observed presence of outflowing material in the UV resonance lines.

scholarly journals AGB winds in interacting binary stars

2020 ◽  
Vol 493 (2) ◽  
pp. 2606-2617 ◽  
Author(s):  
Luis C Bermúdez-Bustamante ◽  
G García-Segura ◽  
W Steffen ◽  
L Sabin
Keyword(s):  
Radiation Pressure ◽  
Stellar Wind ◽  
Binary Stars ◽  
Massive Star ◽  
Density Ratio ◽  
Asymptotic Giant Branch ◽  
Surface Layers ◽  
Outflow Velocity ◽  
Analytical Formulae ◽  
Set Up

ABSTRACT We perform numerical simulations to investigate the stellar wind from interacting binary stars. Our aim is to find analytical formulae describing the outflow structure. In each binary system the more massive star is in the asymptotic giant branch (AGB) and its wind is driven by a combination of pulsations in the stellar surface layers and radiation pressure on dust, while the less massive star is in the main sequence. Time averages of density and outflow velocity of the stellar wind are calculated and plotted as profiles against distance from the centre of mass and colatitude angle. We find that mass is lost mainly through the outer Lagrangian point L2. The resultant outflow develops into a spiral at low distances from the binary. The outflowing spiral is quickly smoothed out by shocks and becomes an excretion disc at larger distances. This leads to the formation of an outflow structure with an equatorial density excess, which is greater in binaries with smaller orbital separation. The pole-to-equator density ratio reaches a maximum value of ∼105 at Roche lobe overflow state. We also find that the gas stream leaving L2 does not form a circumbinary ring for stellar mass ratios above 0.78, when radiation pressure on dust is taken into account. Analytical formulae are obtained by curve fitting the two-dimensional, azimuthally averaged density and outflow velocity profiles. The formulae can be used in future studies to set-up the initial outflow structure in hydrodynamic simulations of common-envelope evolution and formation of planetary nebulae.

scholarly journals LIDT-DD: A New Self-Consistent Debris Disc Model Including Radiation Pressure and Coupling Dynamical and Collisional Evolution

2013 ◽  
Vol 8 (S299) ◽  
pp. 346-347
Author(s):  
Q. Kral ◽  
P. Thebault ◽  
S. Charnoz
Keyword(s):  
Radiation Pressure ◽  
New Model ◽  
Disc Model ◽  
Self Consistent ◽  
Radiation Forces ◽  
Coupling Dynamics ◽  
Long Timescales ◽  
Collisional Evolution

AbstractThe first attempt at developing a fully self-consistent code coupling dynamics and collisions to study debris discs (Kral et al. 2013) is presented. So far, these two crucial mechanisms were studied separately, with N-body and statistical collisional codes respectively, because of stringent computational constraints.We present a new model named LIDT-DD which is able to follow over long timescales the coupled evolution of dynamics (including radiation forces) and collisions in a self-consistent way.

scholarly journals On the influence of magnetic fields in neutral planetary wakes

2016 ◽  
Vol 12 (S328) ◽  
pp. 192-197
Author(s):  
C. Villarreal D’Angelo ◽  
M. Schneiter ◽  
A. Esquivel
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Magnetic Moments ◽  
Radiative Processes ◽  
Planetary Magnetic Fields ◽  
Stellar Magnetic Fields

AbstractWe present a 3D magnetohydrodynamic study of the effect that stellar and planetary magnetic fields have on the calculated Lyα absorption during the planetary transit, employing parameters that resemble the exoplanet HD209458b. We assume a dipolar magnetic field for both the star and the planet, and use the Parker solution to initialize the stellar wind. We also consider the radiative processes and the radiation pressure.We use the numerical MHD code Guacho to run several models varying the values of the planetary and stellar magnetic moments within the range reported in the literature.We found that the presence of magnetic fields influences the escaping neutral planetary material spreading the absorption Lyα line for large stellar magnetic fields.

scholarly journals Stellar-wind theory for O and B stars

1970 ◽  
Vol 36 ◽  
pp. 236-237
Author(s):  
Philip M. Solomon
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Conclusive Evidence ◽  
Driving Mechanism ◽  
Gravitational Acceleration ◽  
Hot Stars ◽  
B Stars ◽  
Wind Theory ◽  
Ultraviolet Observations

The rocket-ultraviolet observations of strong Doppler-shifted absorption lines of Siiv, Civ, Nv and other ions in the spectrum of O and B supergiants clearly indicate a high velocity outflow of matter from these stars. The presence of moderate ionisation stages in the stellar wind is conclusive evidence that the flow cannot be due to a high temperature corona as is the case for the solar wind. It is shown that the driving mechanism for the hot-star mass loss is radiation pressure exerted on the gas through absorption in resonance lines occurring at wavelengths near the maximum of the star's continuum flux. In the upper layers of these stars the outward force per gram of matter due to the radiation pressure can greatly exceed the gravitational acceleration making a static atmosphere impossible.The problem of a steady-state moving reversing layer is formulated and the solution leads to predictions of mass-loss rates as a function of effective temperature and gravity for all hot stars. These results are in substantial agreement with the observations.

Spectroscopic Investigations of Herbig-Ae-Be-Stars

1982 ◽  
Vol 98 ◽  
pp. 501-507
Author(s):  
Ulrich Finkenzeller
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Main Sequence ◽  
Physical Structure ◽  
Pressure Effects ◽  
Theoretical Knowledge ◽  
Be Stars ◽  
Be Star ◽  
Moderate Mass

“Herbig-Ae-Be-Stars” are assumed to be pre-main sequence objects of moderate mass with line emitting envelopes of an unknown nature. From our present theoretical knowledge it is not clear whether the physical structure of these envelopes is dominated by mass accretion or mass loss induced by a stellar wind or radiation pressure effects. Radial velocities and remarks on peculiarities are given for the star HD 200 775, which seems to represent a typical Herbig-Ae-Be-star fairly well. A catalogue of about 60 supposed Herbig-Ae-Be-stars is presented and comments, in particular on the brighter members, are invited.

A Hydrodynamic Modelling of Atmospheric Escape and Absorption Line of WASP-12b

2018 ◽  
Vol 14 (S345) ◽  
pp. 301-303
Author(s):  
N. K. Dwivedi ◽  
M. L. Khodachenko ◽  
I. F. Shaikhislamov ◽  
A. G. Berezutsky ◽  
I. B. Miroshnichenko ◽  
...  
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Energy Input ◽  
Gravitational Interaction ◽  
Radiation Energy ◽  
Tidal Force ◽  
Atmospheric Escape ◽  
Planetary Mass ◽  
Stellar Radiation ◽  
Self Consistent

AbstractSelf-Consistent 2D modelling of stellar wind interaction with the upper atmosphere of WASP-12b has been performed. The two case-scenarios of the planetary material escape and interaction with the stellar wind, namely the ‘blown by the wind’ (without the inclusion of tidal force) and ‘captured by the star’ (with the tidal force) have been modelled under different stellar XUV radiations and stellar wind parameters. In the first scenario, a shock is formed around the planet, and the planetary mass loss is controlled completely by the stellar radiation energy input. In the second scenario, the mass loss is mainly due to the gravitational interaction effects. The dynamics of MGII and related absorption were modelled with three sets of different stellar wind parameters and XUV flux values.

Mass flow and evolution of UW Canis Majoris

1979 ◽  
Vol 83 ◽  
pp. 281-286
Author(s):  
Yoji Kondo ◽  
George E. McCluskey ◽  
Jürgen Rahe
Keyword(s):  
Mass Loss ◽  
Mass Flow ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Primary Component ◽  
Uv Spectrum ◽  
Solar Mass ◽  
Eclipsing Binary

The far-UV spectrum of the eclipsing binary UW CMa (O7f + O-B) had earlier been utilized to derive a mass-loss rate of about 10−6 to 10−5 solar mass per year. The mass flow seems to be basically in the form of a stellar wind emanating from the O7f primary component, with radiation pressure as the controlling factor. The main characteristics that make UW CMa a possible progenitor of a Wolf-Rayet system are discussed.

scholarly journals Spectroscopic Investigations of Herbig-Ae-Be-Stars

1982 ◽  
Vol 98 ◽  
pp. 501-507
Author(s):  
Ulrich Finkenzeller
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Main Sequence ◽  
Physical Structure ◽  
Pressure Effects ◽  
Theoretical Knowledge ◽  
Be Stars ◽  
Be Star ◽  
Moderate Mass

“Herbig-Ae-Be-Stars” are assumed to be pre-main sequence objects of moderate mass with line emitting envelopes of an unknown nature. From our present theoretical knowledge it is not clear whether the physical structure of these envelopes is dominated by mass accretion or mass loss induced by a stellar wind or radiation pressure effects. Radial velocities and remarks on peculiarities are given for the star HD 200 775, which seems to represent a typical Herbig-Ae-Be-star fairly well. A catalogue of about 60 supposed Herbig-Ae-Be-stars is presented and comments, in particular on the brighter members, are invited.

scholarly journals O-Star Winds: Is Rotation Important?

1986 ◽  
Vol 116 ◽  
pp. 93-94
Author(s):  
Raman Prinja ◽  
Ian Howarth
Keyword(s):  
Critical Point ◽  
Radiation Pressure ◽  
Mass Flux ◽  
Stellar Wind ◽  
Terminal Velocity ◽  
Stellar Surface ◽  
Surface Mass ◽  
Pressure Driven

The inclusion of rotation as an ingredient in radiation pressure driven stellar wind models is a nontrivial undertaking. Those bold enough to attempt an investigation of its likely importance include Castor (1979), Abbott (1980), and Marlborough & Zamir (1984), whose work shows that the critical point is expected to move away from the stellar surface with increasing rotation. Observationally, the surface mass flux is predicted to be insensitive to rotation, but the wind acceleration is expected to be less than in a nonrotating star and the terminal velocity smaller.

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