scholarly journals The mass-loss before the end: two luminous blue variables with a collimated stellar wind

2016 ◽  
Vol 12 (S329) ◽  
pp. 69-73
Author(s):  
C. Agliozzo ◽  
C. Trigilio ◽  
C. Buemi ◽  
P. Leto ◽  
G. Umana ◽  
...  
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Stellar Winds ◽  
Companion Star ◽  
Luminous Blue Variables ◽  
Fast Rotation ◽  
Complex Mass

AbstractWe gathered a multiwavelength dataset of two well-known LBVs. We found a complex mass-loss, with evidence of variability, such as has been seen previously. In addition, our data reveal signatures of collimated stellar winds. We propose a new scenario for these two stars where the nebula shaping is influenced by the presence of a companion star and/or fast rotation.

scholarly journals Evolution of binary stars with mass loss

1979 ◽  
Vol 83 ◽  
pp. 383-399
Author(s):  
Janusz Ziółkowski
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Binary Stars ◽  
Binary Systems ◽  
Close Binaries ◽  
Stellar Winds ◽  
Common Envelope ◽  
Weak Evidence ◽  
Orbital Periods ◽  
Detached Binaries

Three situations involving mass loss from binary systems are discussed. (1) Non-conservative mass exchange in semi-detached binaries. No quantitative estimate of this mechanism is possible at present. (2) Common envelope binaries. There are both theoretical and observational indications that this phase of evolution happens to many systems, even to some that are not very close initially (orbital periods ~ years). (3) Stellar winds in binaries. Observational evidence suggests that stellar winds from components of close binaries (especially semi-detached) are significantly stronger than from single stars at the same location in the H-R diagram. Theoretical arguments indicate that in some cases stellar wind may stabilize the component of a binary against the Roche lobe overflow. In some cases there is weak evidence of an anisotropy in the stellar wind.

scholarly journals Colliding stellar wind modelling of the X-ray emission from WR 140

2020 ◽  
Vol 500 (4) ◽  
pp. 4837-4848
Author(s):  
Svetozar A Zhekov
Keyword(s):  
Mass Loss ◽  
Effective Mass ◽  
Stellar Wind ◽  
Mass Loss Rate ◽  
Emission Measure ◽  
Strong Line ◽  
Stellar Winds ◽  
Line Profiles ◽  
X Ray ◽  
Binary Orbit

ABSTRACT We modelled the Chandra and Rossi X-ray Timing Explorer X-ray spectra of the massive binary WR 140 in the framework of the standard colliding stellar wind (CSW) picture. Models with partial electron heating at the shock fronts are a better representation of the X-ray data than those with complete temperature equalization. Emission measure of the X-ray plasma in the CSW region exhibits a considerable decrease at orbital phases near periastron. This is equivalent to variable effective mass-loss rates over the binary orbit. At orbital phases near periastron, a considerable X-ray absorption in excess to that from the stellar winds in WR 140 is present. The standard CSW model provides line profiles that in general do not match well the observed line profiles of the strong line features in the X-ray spectrum of WR 140. The variable effective mass-loss rate could be understood qualitatively in CSW picture of clumpy stellar winds where clumps are efficiently dissolved in the CSW region near apastron but not at periastron. However, future development of CSW models with non-spherically symmetric stellar winds might be needed to get a better correspondence between theory and observations.

scholarly journals Effects of the stellar wind on the Ly α transit of close-in planets

2020 ◽  
Vol 500 (3) ◽  
pp. 3382-3393
Author(s):  
S Carolan ◽  
A A Vidotto ◽  
C Villarreal D’Angelo ◽  
G Hazra
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Escape Rate ◽  
Stellar Winds ◽  
Solar Mass ◽  
Atmospheric Escape ◽  
Exchange Processes ◽  
Sonic Surface

ABSTRACT We use 3D hydrodynamics simulations followed by synthetic line profile calculations to examine the effect increasing the strength of the stellar wind has on observed Ly α transits of a hot Jupiter (HJ) and a warm Neptune (WN). We find that increasing the stellar wind mass-loss rate from 0 (no wind) to 100 times the solar mass-loss rate value causes reduced atmospheric escape in both planets (a reduction of 65 per cent and 40 per cent for the HJ and WN, respectively, compared to the ‘no wind’ case). For weaker stellar winds (lower ram pressure), the reduction in planetary escape rate is very small. However, as the stellar wind becomes stronger, the interaction happens deeper in the planetary atmosphere, and, once this interaction occurs below the sonic surface of the planetary outflow, further reduction in evaporation rates is seen. We classify these regimes in terms of the geometry of the planetary sonic surface. ‘Closed’ refers to scenarios where the sonic surface is undisturbed, while ‘open’ refers to those where the surface is disrupted. We find that the change in stellar wind strength affects the Ly α transit in a non-linear way (note that here we do not include charge-exchange processes). Although little change is seen in planetary escape rates (≃ 5.5 × 1011 g s−1) in the closed to partially open regimes, the Ly α absorption (sum of the blue [−300, −40 km s−1] and red [40, 300 km s−1] wings) changes from 21 to 6 per cent as the stellar wind mass-loss rate is increased in the HJ set of simulations. For the WN simulations, escape rates of ≃ 6.5 × 1010 g s−1 can cause transit absorptions that vary from 8.8 to 3.7 per cent, depending on the stellar wind strength. We conclude that the same atmospheric escape rate can produce a range of absorptions depending on the stellar wind and that neglecting this in the interpretation of Ly α transits can lead to underestimation of planetary escape rates.

scholarly journals Evolutionary effects of stellar rotation of massive stars in their pre-supernova environments

2010 ◽  
Vol 6 (S272) ◽  
pp. 99-100
Author(s):  
Brenda Pérez-Rendón ◽  
Horacio Pineda-León ◽  
Alfredo Santillán ◽  
Liliana Hernández-Cervantes
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Main Sequence ◽  
Massive Stars ◽  
Stellar Winds ◽  
Stellar Rotation ◽  
Main Sequence Stars ◽  
Mixing Processes ◽  
Circumstellar Medium ◽  
Loss Rates

AbstractMassive main sequence stars are fast rotators. Stellar rotation affects massive stellar rotation due to rotationally induced mixing processes, the increase of mass loss rates, etc. and also affects the circumstellar medium due to their interaction with the stellar wind. The parameters of stellar winds depends on stellar parameters so the wind parameters change as the star evolves, coupling the evolution of circumstellar medium to the star itself. In this work we used a stellar code to build models of two massive stars (30 and 40 M⊙) and we used their wind parameters to simulate the hydrodynamics of their surrounding gas with the ZEUS-3D code in order to explore the effects of stellar rotation in the pre-supernova environments.

scholarly journals Local environments of SNe Ic and Ic-BL

2015 ◽  
Vol 11 (A29B) ◽  
pp. 278-279
Author(s):  
Jonatan Selsing ◽  
Lise Christensen ◽  
Christina Thöne ◽  
Maryam Modjaz
Keyword(s):  
Mass Loss ◽  
Stellar Populations ◽  
Initial Mass ◽  
Stellar Winds ◽  
Sample Type ◽  
Companion Star ◽  
Physical Conditions ◽  
Local Environments ◽  
Local Explosion ◽  
Dependent Mass

AbstractWe have observed the local explosion environments of a sample Type Ic and Type Ic-BL Supernove (SNe) selected from both targeted and non-targeted surveys using VLT/VIMOS in IFU-mode. It is believed that by probing the local surroundings of the parent stellar populations of these types of SNe, valuable information can be gained about the physical conditions, which affect the type of SNe produced. The different kinds of SNe produced are determined by the initial mass and metallicity of the stellar progenitor, as well as by the metallicity-dependent mass loss in the stellar winds at the end phase of their evolution and the interaction with a sufficiently close companion star.

scholarly journals UV Spectroscopy of Massive Stars

Galaxies ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 60
Author(s):  
D. John Hillier
Keyword(s):  
Mass Loss ◽  
Effective Temperature ◽  
Massive Stars ◽  
Uv Spectroscopy ◽  
Uv Spectra ◽  
Stellar Winds ◽  
Luminous Blue Variables ◽  
Weak Wind ◽  
Made In ◽  
Loss Rates

We present a review of UV observations of massive stars and their analysis. We discuss O stars, luminous blue variables, and Wolf–Rayet stars. Because of their effective temperature, the UV (912−3200 Å) provides invaluable diagnostics not available at other wavebands. Enormous progress has been made in interpreting and analysing UV data, but much work remains. To facilitate the review, we provide a brief discussion on the structure of stellar winds, and on the different techniques used to model and interpret UV spectra. We discuss several important results that have arisen from UV studies including weak-wind stars and the importance of clumping and porosity. We also discuss errors in determining wind terminal velocities and mass-loss rates.

scholarly journals X-ray Shaping of Planetary Nebulae

2018 ◽  
Author(s):  
Martin A Guerrero
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Essential Role ◽  
Planetary Nebulae ◽  
Stellar Winds ◽  
Physical Processes ◽  
X Ray ◽  
Hot Gas ◽  
Energy And Momentum ◽  
Central Stars

The stellar winds of the central stars of planetary nebulae play an essential role in planetary nebulae shaping. In the interacting stellar winds model, the fast stellar wind injects energy and momentum which are transfered to the nebular envelope through an X-ray-emitting hot bubble. Together with other physical processes, such as the ionization of the nebular envelope, the asymmetrical mass-loss in the AGB, and the action of collimated outflows and magnetic fields, the presurized hot gas determines the expansion and evolution of planetary nebulae. \emph{Chandra} and \emph{XMM-Newton} have provided us with detailed information of this hot gas. Here in this talk I will review our current understanding of the effects of the fast stellar wind in the shaping and evolution of planetary nebulae and give some hints of the promissing future of this research.

scholarly journals Rotation of B[e] Supergiants, Luminous Blue Variables and Wolf-Rayet Stars

2004 ◽  
Vol 215 ◽  
pp. 97-106 ◽  
Author(s):  
Philippe Eenens
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Rapid Rotation ◽  
Luminous Blue Variables ◽  
Common Features ◽  
Fast Rotation ◽  
Late Evolution

A brief review of the observational properties of evolved massive stars is presented. In the pursuit of clues for their rotation, formidable difficulties are encountered. At the same time, common features emerge between B[e] supergiants, Luminous Blue Variables and Wolf-Rayet stars. Several indications of rapid rotation are found, mostly indirect ones, in each class. It is shown that fast rotation can probably survive the mass loss events which characterize the late evolution of massive stars.

scholarly journals Stellar Wind Theories

1980 ◽  
Vol 5 ◽  
pp. 591-600
Author(s):  
A. G. Hearn
Keyword(s):  
Solar Wind ◽  
Mass Loss ◽  
Stellar Wind ◽  
Extreme Case ◽  
Stellar Atmosphere ◽  
Stellar Winds ◽  
Mean Flow ◽  
Continuous Mass ◽  
Flow Through ◽  
Energy And Momentum

The term stellar wind is used nowadays to describe any more or less continuous mass loss from a star. With the observations made with satellites in recent years it is becoming clear that most stars are undergoing this form of mass loss, though its magnitude can be very different from one star to another. The term stellar wind does not include the more eruptive forms of mass loss such as novae, the ejection of mass in shells or mass loss as a result of flares.Stellar winds are maintained by energy and momentum deposited in the outer layers of a stellar atmosphere. The deposition of energy causes the heating of a chromosphere and corona, so that the theory of stellar winds cannot really be separated from the theory of coronal heating. Energy and momentum can both be deposited by the same mechanism. For example if a corona is heated by the dissipation of a wave which deposits energy, the same wave can change the momentum of the mean flow through wave pressure and this can happen even in the extreme case of no dissipation of the wave.The foundation of the theory of stellar winds was laid by Parker (1958) in his theory of the solar wind. A useful review of this work has been given by Parker (1965). The theory of the solar wind in its simplest form is deduced from the equation of motion combined with the equations of continuity and state.

scholarly journals GJ 436b and the stellar wind interaction: simulations constraints using Lyα and Hα transits

2020 ◽  
Author(s):  
Carolina Villarreal D’Angelo ◽  
Aline A Vidotto ◽  
Alejandro Esquivel ◽  
Gopal Hazra ◽  
Allison Youngblood
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Planetary System ◽  
Neutral Hydrogen ◽  
Hydrogen Atmosphere ◽  
Planetary Atmosphere ◽  
Hydrodynamic Simulations ◽  
Stellar Disc ◽  
Planetary Mass ◽  
Best Fit

Abstract The GJ 436 planetary system is an extraordinary system. The Neptune-size planet that orbits the M3 dwarf revealed in the Lyα line an extended neutral hydrogen atmosphere. This material fills a comet-like tail that obscures the stellar disc for more than 10 hours after the planetary transit. Here, we carry out a series of 3D radiation hydrodynamic simulations to model the interaction of the stellar wind with the escaping planetary atmosphere. With these models, we seek to reproduce the $\sim 56\%$ absorption found in Lyα transits, simultaneously with the lack of absorption in Hα transit. Varying the stellar wind strength and the EUV stellar luminosity, we search for a set of parameters that best fit the observational data. Based on Lyα observations, we found a stellar wind velocity at the position of the planet to be around [250-460] km s−1 with a temperature of [3 − 4] × 105 K. The stellar and planetary mass loss rates are found to be 2 × 10−15 M⊙ yr−1 and ∼[6 − 10] × 109 g s−1, respectively, for a stellar EUV luminosity of [0.8 − 1.6] × 1027 erg s−1. For the parameters explored in our simulations, none of our models present any significant absorption in the Hα line in agreement with the observations.

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