scholarly journals Ring nebulae around massive stars throughout the Hertzsprung-Russell diagram

2003 ◽  
Vol 212 ◽  
pp. 585-595 ◽  
Author(s):  
You-Hua Chu
Keyword(s):  
Interstellar Medium ◽  
Mass Loss ◽  
Stellar Wind ◽  
Massive Star ◽  
Main Sequence ◽  
Massive Stars ◽  
X Ray ◽  
Red Giant ◽  
Ring Nebulae ◽  
Luminous Blue Variable

Massive stars evolve across the H-R diagram, losing mass along the way and forming a variety of ring nebulae. During the main sequence stage, the fast stellar wind sweeps up the ambient interstellar medium to form an interstellar bubble. After a massive star evolves into a red giant or a luminous blue variable, it loses mass copiously to form a circumstellar nebula. As it evolves further into a WR star, the fast WR wind sweeps up the previous mass loss and forms a circumstellar bubble. Observations of ring nebulae around massive stars not only are fascinating, but also are useful in providing templates to diagnose the progenitors of supernovae from their circumstellar nebulae. In this review, I will summarize the characteristics of ring nebulae around massive stars throughout the H-R diagram, show recent advances in X-ray observations of bubble interiors, and compare supernovae's circumstellar nebulae with known types of ring nebulae around massive stars.

Mass Loss and Stellar Wind in Massive X-Ray Binaries

1980 ◽  
Vol 5 ◽  
pp. 541-547
Author(s):  
H. F. Henrichs
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Binary Systems ◽  
Massive Stars ◽  
Compact Star ◽  
X Rays ◽  
Early Type ◽  
X Ray ◽  
X Ray Binaries ◽  
Loss Rates

A number of massive stars of early type is found in X-ray binary systems. The catalog of Bradt et al. (1979) contains 21 sources optically identified with massive stars ranging in spectral type from 06 to B5 out of which 13 are (nearly) unevolved stars and 8 are supergiants. Single stars of this type generally show moderate to strong stellar winds. The X-rays in these binaries originate from accretion onto a compact companion (we restrict the discussion to this type of X-rays).We consider the compact star as a probe traveling through the stellar wind. This probe enables us to derive useful information about the mass outflow of massive stars.After presenting the basic data we derive an upper limit to mass loss rates of unevolved early type stars by studying X-ray pulsars. Next we consider theoretical predictions concerning the influence of X-rays on the stellar wind and compare these with the observations. Finally, using new data from IUE, we draw some conclusions about mass loss rates and velocity laws as derived from X-ray binaries.

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 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 Instabilities in massive stars

2003 ◽  
Vol 212 ◽  
pp. 281-290 ◽  
Author(s):  
Stanley P. Owocki
Keyword(s):  
Physical Properties ◽  
Mass Loss ◽  
Stellar Wind ◽  
Massive Stars ◽  
Dynamical Instability ◽  
Radiation Hydrodynamics ◽  
Stellar Rotation ◽  
Eddington Limit ◽  
Luminous Blue Variable

A defining property of massive stars is the dominant, dynamical role played by radiation throughout the stellar interior, atmosphere, and wind. Associated with this radiation hydrodynamics are several distinct kinds of instabilities that can lead to convection in both core and envelope, clumping in atmosphere and wind outflow, and perhaps even the dramatic mass loss outbursts associated with Luminous Blue Variable phases. Here I review these instabilities with emphasis on basic physical properties of radiative driving. I draw on two specific examples of dynamical instability, namely the strong instability associated with line-driving of a stellar wind outflow, and the global stellar instabilities associated with approaching or exceeding a modified Eddington limit. I conclude with a brief mention of recent ideas on the role of stellar rotation in the shaping of bipolar LBV outbursts.

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 Observational tests for overshoot and opacity enhancement based on massive stars

1984 ◽  
Vol 105 ◽  
pp. 333-336
Author(s):  
G. Bertelli ◽  
A. Bressan ◽  
C. Chiosi
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Classical Limit ◽  
Main Sequence ◽  
Massive Stars ◽  
Heavy Elements ◽  
Moderate Increase ◽  
Theoretical Expectation ◽  
Sequence Band ◽  
Convective Overshoot

It is shown that a moderate increase in the opacity due to heavy elements in models of massive stars, incorporating convective overshoot and mass loss by stellar wind, can remove the well known discrepancy between theoretical expectation and observed frequencies of luminous stars in the HR diagram. These models in fact extend their main sequence band far beyond the classical limit.

scholarly journals Massive star evolution: from the early to the present day Universe

2008 ◽  
Vol 4 (S252) ◽  
pp. 317-327 ◽  
Author(s):  
Georges Meynet ◽  
Sylvia Ekström ◽  
Cyril Georgy ◽  
André Maeder ◽  
Raphael Hirschi
Keyword(s):  
Interstellar Medium ◽  
Mass Loss ◽  
Radiation Field ◽  
Massive Star ◽  
Massive Stars ◽  
Mechanical Energy ◽  
Axial Rotation ◽  
Star Evolution ◽  
Massive Star Evolution ◽  
Hr Diagram

AbstractMass loss and axial rotation are playing key roles in shaping the evolution of massive stars. They affect the tracks in the HR diagram, the lifetimes, the surface abundances, the hardness of the radiation field, the chemical yields, the presupernova status, the nature of the remnant, the mechanical energy released in the interstellar medium, etc. . . In this paper, after recalling a few characteristics of mass loss and rotation, we review the effects of these two processes at different metallicities. Rotation probably has its most important effects at low metallicities, while mass loss and rotation deeply affect the evolution of massive stars at solar and higher than solar metallicities.

scholarly journals Radiation-Driven Stellar Eruptions

Galaxies ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 10 ◽  
Author(s):  
Kris Davidson
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Central Region ◽  
Massive Stars ◽  
Variable Stars ◽  
Blast Waves ◽  
Subsequent Evolution ◽  
Fundamental Causes ◽  
Radiative Output ◽  
Luminous Blue Variable

Very massive stars occasionally expel material in colossal eruptions, driven by continuum radiation pressure rather than blast waves. Some of them rival supernovae in total radiative output, and the mass loss is crucial for subsequent evolution. Some are supernova impostors, including SN precursor outbursts, while others are true SN events shrouded by material that was ejected earlier. Luminous Blue Variable stars (LBV’s) are traditionally cited in relation with giant eruptions, though this connection is not well established. After four decades of research, the fundamental causes of giant eruptions and LBV events remain elusive. This review outlines the basic relevant physics, with a brief summary of essential observational facts. Reasons are described for the spectrum and emergent radiation temperature of an opaque outflow. Proposed mechanisms are noted for instabilities in the star’s photosphere, in its iron opacity peak zones, and in its central region. Various remarks and conjectures are mentioned, some of them relatively unfamiliar in the published literature.

scholarly journals The VLT-FLAMES Tarantula Survey

2016 ◽  
Vol 12 (S329) ◽  
pp. 279-286
Author(s):  
Jorick S. Vink ◽  
C.J. Evans ◽  
J. Bestenlehner ◽  
C. McEvoy ◽  
O. Ramírez-Agudelo ◽  
...  
Keyword(s):  
Mass Loss ◽  
Main Sequence ◽  
Massive Stars ◽  
Mass Function ◽  
Large Magellanic Cloud ◽  
Initial Mass Function ◽  
Data Set ◽  
Large Program ◽  
Medium Resolution ◽  
Key Questions

AbstractWe present a number of notable results from the VLT-FLAMES Tarantula Survey (VFTS), an ESO Large Program during which we obtained multi-epoch medium-resolution optical spectroscopy of a very large sample of over 800 massive stars in the 30 Doradus region of the Large Magellanic Cloud (LMC). This unprecedented data-set has enabled us to address some key questions regarding atmospheres and winds, as well as the evolution of (very) massive stars. Here we focus on O-type runaways, the width of the main sequence, and the mass-loss rates for (very) massive stars. We also provide indications for the presence of a top-heavy initial mass function (IMF) in 30 Dor.

scholarly journals What Do We Really Know About the Winds of Massive Stars?

2007 ◽  
Vol 3 (S250) ◽  
pp. 89-96
Author(s):  
D. John Hillier
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Standard Theory ◽  
Stellar Winds ◽  
X Rays ◽  
X Ray ◽  
Stellar Photosphere ◽  
Weak Winds ◽  
Ionization Balance ◽  
Loss Rates

AbstractThe standard theory of radiation driven winds has provided a useful framework to understand stellar winds arising from massive stars (O stars, Wolf-Rayet stars, and luminous blue variables). However, with new diagnostics, and advances in spectral modeling, deficiencies in our understanding of stellar winds have been thrust to the forefront of our research efforts. Spectroscopic observations and analyses have shown the importance of inhomogeneities in stellar winds, and revealed that there are fundamental discrepancies between predicted and theoretical mass-loss rates. For late O stars, spectroscopic analyses derive mass-loss rates significantly lower than predicted. For all O stars, observed X-ray fluxes are difficult to reproduce using standard shock theory, while observed X-ray profiles indicate lower mass-loss rates, the potential importance of porosity effects, and an origin surprisingly close to the stellar photosphere. In O stars with weak winds, X-rays play a crucial role in determining the ionization balance, and must be taken into account.

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