scholarly journals How to inflate a wind-blown bubble

2021 ◽  
Vol 508 (2) ◽  
pp. 1768-1776
Author(s):  
J M Pittard ◽  
C J Wareing ◽  
M M Kupilas
Keyword(s):  
Stellar Wind ◽  
External Medium ◽  
Reference Model ◽  
Massive Stars ◽  
Ambient Medium ◽  
Stellar Winds ◽  
Relative Importance ◽  
Numerical Resolution ◽  
Maximum Value ◽  
Injection Region

ABSTRACT Stellar winds are one of several ways that massive stars can affect the star formation process on local and galactic scales. In this paper, we investigate the numerical resolution needed to inflate an energy-driven stellar wind bubble in an external medium. We find that the radius of the wind injection region, rinj, must be below a maximum value, rinj,max, in order for a bubble to be produced, but must be significantly below this value if the bubble properties are to closely agree with analytical predictions. The final bubble momentum is within 25 per cent of the value from a higher resolution reference model if χ = rinj/rinj,max = 0.1. Our work has significance for the amount of radial momentum that a wind-blown bubble can impart to the ambient medium in simulations, and thus on the relative importance of stellar wind feedback.

scholarly journals Bubbles and Superbubbles: Observations and Theory

2007 ◽  
Vol 3 (S250) ◽  
pp. 341-354 ◽  
Author(s):  
You-Hua Chu
Keyword(s):  
Turbulent Mixing ◽  
Thermal Conduction ◽  
Massive Stars ◽  
Ambient Medium ◽  
Surrounding Medium ◽  
Shell Structures ◽  
Stellar Winds ◽  
Hot Gas ◽  
Dense Shell ◽  
Supernova Explosions

AbstractMassive stars inject energy into the surrounding medium and form shell structures. Bubbles are blown by fast stellar winds from individual massive stars, while superbubbles are blown by fast stellar winds and supernova explosions from groups of massive stars. Bubbles and superbubbles share a similar overall structure: a swept-up dense shell with an interior filled by low-density hot gas. Physical properties of a bubble/superbubble can be affected by magnetic field, thermal conduction, turbulent mixing, inhomogeneous ambient medium, etc. I will review recent progresses on observations and compare them to theoretical expectations for (1) swept-up dense shells, (2) hot interiors, and (3) interface between a dense shell and its interior hot gas.

Formation of Ring Nebulae around Massive Stars in LMC HII Regions

1999 ◽  
Vol 190 ◽  
pp. 134-135
Author(s):  
Kerstin Weis ◽  
Wolfgang J. Duschl
Keyword(s):  
Main Sequence ◽  
Massive Stars ◽  
Ambient Medium ◽  
Hii Regions ◽  
Large Magellanic Cloud ◽  
High Mass ◽  
Stellar Winds ◽  
High Mass Loss ◽  
Form Ring ◽  
Ring Nebulae

Massive stars have strong stellar winds and consequently a high mass loss during their lifetimes. Therefore they can form ring nebulae by stellar winds sweeping up the ambient medium in the main sequence phase or through wind-wind interaction or eruptions in the evolved state. We present preliminary results of a search for single bubbles and ring-nebulae around massive stars in the Large Magellanic Cloud (LMC).

scholarly journals X-ray diagnostics of massive star winds

2016 ◽  
Vol 12 (S329) ◽  
pp. 151-155
Author(s):  
L. M. Oskinova ◽  
R. Ignace ◽  
D. P. Huenemoerder
Keyword(s):  
High Resolution ◽  
Stellar Wind ◽  
Massive Star ◽  
Massive Stars ◽  
Stellar Winds ◽  
X Rays ◽  
Early Type ◽  
Stellar Rotation ◽  
X Ray ◽  
Early Type Stars

AbstractObservations with powerful X-ray telescopes, such as XMM-Newton and Chandra, significantly advance our understanding of massive stars. Nearly all early-type stars are X-ray sources. Studies of their X-ray emission provide important diagnostics of stellar winds. High-resolution X-ray spectra of O-type stars are well explained when stellar wind clumping is taking into account, providing further support to a modern picture of stellar winds as non-stationary, inhomogeneous outflows. X-ray variability is detected from such winds, on time scales likely associated with stellar rotation. High-resolution X-ray spectroscopy indicates that the winds of late O-type stars are predominantly in a hot phase. Consequently, X-rays provide the best observational window to study these winds. X-ray spectroscopy of evolved, Wolf-Rayet type, stars allows to probe their powerful metal enhanced winds, while the mechanisms responsible for the X-ray emission of these stars are not yet understood.

scholarly journals Ring Nebulae Around Massive Stars

1991 ◽  
Vol 143 ◽  
pp. 349-364
Author(s):  
You-Hua Chu
Keyword(s):  
Stellar Evolution ◽  
Spectral Properties ◽  
Massive Stars ◽  
Ambient Medium ◽  
Stellar Winds ◽  
Luminous Blue Variables ◽  
Stellar Properties ◽  
Ring Nebulae ◽  
Central Stars ◽  
Temperature Correlations

Ring nebulae have been found around WR stars, OB and Of stars, and luminous blue variables. Ring nebulae are formed by the interaction between the central stars and their ambient medium via different combinations of stellar winds, ejecta, and radiation. The spectral properties of the nebulae can be used to diagnose the stellar properties, such as luminosity and effective temperature. Correlations between ring nebulae and their central stars may be used to check scenarios of stellar evolution.

scholarly journals The Evolution of the Circumstellar and Interstellar Medium Around Massive Stars

2007 ◽  
Vol 3 (S250) ◽  
pp. 355-360
Author(s):  
S. Jane Arthur
Keyword(s):  
Stellar Wind ◽  
Massive Star ◽  
Main Sequence ◽  
Massive Stars ◽  
Central Star ◽  
Stellar Winds ◽  
X Rays ◽  
Hydrodynamic Calculations ◽  
The Impact ◽  
Size Scales

AbstractThroughout their lives massive stars modify their environment through their ionizing photons and strong stellar winds. Here, I present coupled radiation-hydrodynamic calculations of the evolution of the bubbles and nebulae surrounding massive stars. The evolution is followed from the main sequence through the Wolf-Rayet stage and shows that structures are formed in the ISM out to some tens of parsecs radius. Closer to the star, instabilities lead to the breakup of swept-up wind shells. The photoevaporated flows from the resulting clumps interact with the stellar wind from the central star, which leads to the production of soft X-rays. I examine the consequences for the different observable structures at all time and size scales and evaluate the impact that the massive star has on its environment.

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 On the ring nebulae around runaway Wolf–Rayet stars

2020 ◽  
Vol 496 (3) ◽  
pp. 3906-3911
Author(s):  
D M-A Meyer ◽  
L M Oskinova ◽  
M Pohl ◽  
M Petrov
Keyword(s):  
High Latitude ◽  
Stellar Wind ◽  
Near Infrared ◽  
Moving Objects ◽  
Galactic Plane ◽  
Massive Stars ◽  
Ambient Medium ◽  
Bow Shock ◽  
Fast Wind ◽  
Bow Shocks

ABSTRACT Wolf–Rayet stars are advanced evolutionary stages of massive stars. Despite their large mass-loss rates and high wind velocities, none of them displays a bow shock, although a fraction of them are classified as runaway. Our 2.5-D numerical simulations of circumstellar matter around a $60\mbox{-}\rm M_{\odot }$ runaway star show that the fast Wolf–Rayet stellar wind is released into a wind-blown cavity filled with various shocks and discontinuities generated throughout the preceding evolutionary phases. The resulting fast-wind–slow-wind interaction leads to the formation of spherical shells of swept-up dusty material similar to those observed in the near-infrared at $24\, \rm \mu \rm m$ with Spitzer, which appear to be comoving with the runaway massive stars, regardless of their proper motion and/or the properties of the local ambient medium. We interpret bright infrared rings around runaway Wolf–Rayet stars in the Galactic plane as an indication of their very high initial masses and complex evolutionary history. Stellar-wind bow shocks become faint as stars run in diluted media, therefore our results explain the absence of bow shocks detected around Galactic Wolf–Rayet stars, such as the high-latitude, very fast-moving objects WR71, WR124 and WR148. Our results show that the absence of a bow shock is consistent with the runaway nature of some Wolf–Rayet stars. This questions the in situ star formation scenario of high-latitude Wolf–Rayet stars in favour of dynamical ejection from birth sites in the Galactic plane.

scholarly journals Physical Processes in Nebular Shells and the Interpretation of Nebular Spectra

1983 ◽  
Vol 103 ◽  
pp. 219-227
Author(s):  
J. Patrick Harrington
Keyword(s):  
Charge Transfer ◽  
Simple Model ◽  
Stellar Wind ◽  
High Velocity ◽  
Planetary Nebulae ◽  
Geometrical Parameters ◽  
Stellar Winds ◽  
Physical Processes ◽  
Rapid Cooling ◽  
Particle Distributions

Computed models are now recognized as useful tools for interpretation of the spectra of planetary nebulae. However, even the most detailed models need geometrical parameters such as filling factors which are poorly determined by observations. Some effects may be seen more clearly by modeling the stratification than by just using total fluxes. A simple model for NGC 6720 is presented which reproduces the behavior of (Ne III) λ3869 observed by Hawley and Miller (1977), clearly showing the effects of charge transfer. The behavior of C II λ4267 remains puzzling. Finally, we comment on the interaction of high velocity stellar winds with nebular shells. Non-equilibrium particle distributions at the contact between the shocked stellar wind and the nebula may result in the rapid cooling of the shocked gas.

scholarly journals Stellar wind effects on the atmospheres of close-in giants: a possible reduction in escape instead of increased erosion

2020 ◽  
Vol 494 (2) ◽  
pp. 2417-2428 ◽  
Author(s):  
A A Vidotto ◽  
A Cleary
Keyword(s):  
Parameter Space ◽  
Stellar Wind ◽  
Planetary Atmospheres ◽  
External Pressure ◽  
Stellar Winds ◽  
Wind Effects ◽  
Atmospheric Escape ◽  
Large Pressure ◽  
Ram Pressure ◽  
Host Stars

ABSTRACT The atmospheres of highly irradiated exoplanets are observed to undergo hydrodynamic escape. However, due to strong pressures, stellar winds can confine planetary atmospheres, reducing their escape. Here, we investigate under which conditions atmospheric escape of close-in giants could be confined by the large pressure of their host star’s winds. For that, we simulate escape in planets at a range of orbital distances ([0.04, 0.14] au), planetary gravities ([36, 87 per cent] of Jupiter’s gravity), and ages ([1, 6.9] Gyr). For each of these simulations, we calculate the ram pressure of these escaping atmospheres and compare them to the expected stellar wind external pressure to determine whether a given atmosphere is confined or not. We show that although younger close-in giants should experience higher levels of atmospheric escape, due to higher stellar irradiation, stellar winds are also stronger at young ages, potentially reducing escape of young exoplanets. Regardless of the age, we also find that there is always a region in our parameter space where atmospheric escape is confined, preferably occurring at higher planetary gravities and orbital distances. We investigate confinement of some known exoplanets and find that the atmosphere of several of them, including π Men c, should be confined by the winds of their host stars, thus potentially preventing escape in highly irradiated planets. Thus, the lack of hydrogen escape recently reported for π Men c could be caused by the stellar wind.

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