Chemical enrichment from Wolf-Rayet stellar winds

Stellar winds contribute together with supernovae explosions to the chemical enrichment of the interstellar medium. We recall how the metallicity dependence of the stellar winds implies a metallicity dependence of the stellar yields. We show that an increase of the initial angular velocity has different effects than an increase of the mass loss rates. Wolf-Rayet stars appear as important sources of 19F and 26Al. They are the favoured candidates for the 22Ne anomaly observed in the Galactic cosmic ray sources. They may also have injected into the proto-solar nebula short-lived radionuclides as 26Al, 36Cl, 41Ca, 107Pd and 205Pb.

Asteroseismology of luminous red giants with Kepler. II. Dependence of mass loss on pulsations and radiation

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3970 ◽

2020 ◽

Author(s):

Jie Yu ◽

Saskia Hekker ◽

Timothy R Bedding ◽

Dennis Stello ◽

Daniel Huber ◽

...

Keyword(s):

Mass Loss ◽

Mass Loss Rate ◽

Asymptotic Giant Branch ◽

Red Giants ◽

Asymptotic Giant Branch Stars ◽

Chemical Enrichment ◽

Dust Mass ◽

Red Giant ◽

The Masses ◽

Abstract Mass loss by red giants is an important process to understand the final stages of stellar evolution and the chemical enrichment of the interstellar medium. Mass-loss rates are thought to be controlled by pulsation-enhanced dust-driven outflows. Here we investigate the relationships between mass loss, pulsations, and radiation, using 3213 luminous Kepler red giants and 135000 ASAS–SN semiregulars and Miras. Mass-loss rates are traced by infrared colours using 2MASS and WISE and by observed-to-model WISE fluxes, and are also estimated using dust mass-loss rates from literature assuming a typical gas-to-dust mass ratio of 400. To specify the pulsations, we extract the period and height of the highest peak in the power spectrum of oscillation. Absolute magnitudes are obtained from the 2MASS Ks band and the Gaia DR2 parallaxes. Our results follow. (i) Substantial mass loss sets in at pulsation periods above ∼60 and ∼100 days, corresponding to Asymptotic-Giant-Branch stars at the base of the period-luminosity sequences C′ and C. (ii) The mass-loss rate starts to rapidly increase in semiregulars for which the luminosity is just above the red-giant-branch tip and gradually plateaus to a level similar to that of Miras. (iii) The mass-loss rates in Miras do not depend on luminosity, consistent with pulsation-enhanced dust-driven winds. (iv) The accumulated mass loss on the Red Giant Branch consistent with asteroseismic predictions reduces the masses of red-clump stars by 6.3%, less than the typical uncertainty on their asteroseismic masses. Thus mass loss is currently not a limitation of stellar age estimates for galactic archaeology studies.

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308020371 ◽

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 ◽

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.

Clumps in stellar winds

ASTRA Proceedings ◽

10.5194/ap-1-39-2014 ◽

2014 ◽

Vol 1 ◽

pp. 39-41 ◽

Cited By ~ 1

Author(s):

J. S. Vink

Keyword(s):

Mass Loss ◽

Massive Stars ◽

Stellar Winds ◽

Present Evidence ◽

Close Proximity ◽

Stellar Photosphere ◽

Abstract. We discuss the origin and quantification of wind clumping and mass–loss rates (Ṁ), particularly in close proximity to the Eddington (Γ) limit, relevant for very massive stars (VMS). We present evidence that clumping may not be the result of the line-deshadowing instability (LDI), but that clumps are already present in the stellar photosphere.

Stellar Winds and Mass-Loss Rates from Be Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900038055 ◽

1982 ◽

Vol 98 ◽

pp. 377-385 ◽

Cited By ~ 1

Author(s):

Theodore P. Snow

Keyword(s):

Mass Loss ◽

Stellar Evolution ◽

Stellar Winds ◽

Be Stars ◽

Line Profiles ◽

Sample Group ◽

Show Evidence ◽

Acceleration Zone ◽

Low Levels ◽

Resonance-line profiles of SiIII and SiIV lines in 22 B and Be stars have been analyzed in the derivation of mass-loss rates. Of the 19 known Be or shell stars in the sample group, all but one show evidence of winds. It is argued that for stars of spectral type B1.5 and later, SiIII and SiIV are the dominant stages of ionization, and this conclusion, together with theoretical fits to the line profiles, leads to mass-loss rates between 10-11 and 3 × 10-9 for the stars. The rate of mass loss does not correlate simply with stellar parameters, and probably is variable with time. The narrow FeIII shell lines often seen in the ultraviolet spectra of Be stars may arise at low levels in the wind, below the strong acceleration zone. The mass-loss rates from Be stars are apparently insufficient to affect stellar evolution.

Direct Numerical Simulations of Cosmic-ray Acceleration at Dense Circumstellar Medium: Magnetic-field Amplification and Maximum Energy

The Astrophysical Journal ◽

10.3847/1538-4357/ac21ce ◽

2021 ◽

Vol 922 (1) ◽

pp. 7

Author(s):

Tsuyoshi Inoue ◽

Alexandre Marcowith ◽

Gwenael Giacinti ◽

Allard Jan van Marle ◽

Shogo Nishino

Keyword(s):

Cosmic Rays ◽

Mass Loss ◽

Supernova Remnants ◽

Mass Loss Rate ◽

Spherical Geometry ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Maximum Energy ◽

Blast Waves ◽

Abstract Galactic cosmic rays are believed to be accelerated at supernova remnants. However, whether supernova remnants can be PeV is still very unclear. In this work we argue that PeV cosmic rays can be accelerated during the early phase of a supernova blast-wave expansion in dense red supergiant winds. We solve in spherical geometry a system combining a diffusive–convection equation that treats cosmic-ray dynamics coupled to magnetohydrodynamics to follow gas dynamics. A fast shock expanding in a dense ionized wind is able to trigger fast, non-resonant streaming instability over day timescales and energizes cosmic rays even under the effect of p–p losses. We find that such environments produce PeV blast waves, although the maximum energy depends on various parameters such as the injection rate and mass-loss rate of the winds. Multi-PeV energies can be reached if the progenitor mass-loss rates are of the order of 10−3 M ⊙ yr−1. It has been recently proposed that, prior to the explosion, hydrogen-rich massive stars can produce enhanced mass-loss rates. These enhanced rates would then favor the production of a PeV phase in early times after shock breakout.

The Surroundings of Gamma-Ray Bursts: Constraints on Progenitors

10.1017/s0252921100009520 ◽

2005 ◽

Vol 192 ◽

pp. 441-450

Author(s):

Roger A. Chevalier

Keyword(s):

Interstellar Medium ◽

Mass Loss ◽

Massive Star ◽

Gamma Ray ◽

Gamma Ray Bursts ◽

Uniform Density ◽

Stellar Winds ◽

Wind Environment ◽

Low Mass ◽

Pulsar Wind

SummaryThe association of a supernova with a gamma-ray burst (GRB 030329) implies a massive star progenitor, which is expected to have an environment formed by pre-burst stellar winds. Although some sources are consistent with the expected wind environment, many are not, being better fit by a uniform density environment. One possibility is that this is a shocked wind, close to the burst because of a high interstellar pressure and a low mass loss density. Alternatively, there is more than one kind of burst progenitor, some of which interact directly with the interstellar medium. Another proposed environment is a pulsar wind bubble that has expanded inside a supernova, which requires that the supernova precede the burst.

Stellar Winds in A-Type Supergiants

10.1017/s0252921100023666 ◽

1989 ◽

Vol 120 ◽

pp. 146-151

Author(s):

A. Talavera ◽

A.I. Gomez de Castro

Keyword(s):

Interstellar Medium ◽

Mass Loss ◽

Stellar Winds ◽

Cool Stars ◽

Radiative Acceleration

The contribution of A supergiant stars to the return of mass and energy to the interstellar medium is not very important. Abbott (1982) analised a sample of early stars and concluded that B and A supergiants provided less than 8 % of the mass input to the ISM by stellar winds. However, A-type supergiants are important in the framework of the stellar winds-mass loss phenomenology since they are located at the boundary between hot and cool stars, where radiative acceleration may not be sufficiently efficient to drive the wind.

Mass loss rates for twenty one Wolf-Rayet stars

10.1017/s0252921100094604 ◽

1981 ◽

Vol 59 ◽

pp. 65-65

Author(s):

M.J. Barlow ◽

L.J. Smith ◽

A.J. Willis

Keyword(s):

Kinetic Energy ◽

Interstellar Medium ◽

Mass Loss ◽

Radiation Pressure ◽

Massive Star ◽

Total Kinetic Energy ◽

The Mean ◽

AbstractMass loss rates have been derived for twenty one WR stars encompassing most subtypes in the WN and WC sequences, from measurements of their infrared free-free fluxes. The resultant mass loss rates show a range of only a factor of four. WC stars generally have larger mass loss rates than WN stars, the mean rates being Ṁ(WC) = 4.1x10-5 M⊙y-1 and Ṁ(WN) = 2.7x10-5 M⊙y-1. Optical and ultraviolet data have been used to estimate bolometric luminosities for a range of WR spectral types, and it is shown that the derived mass loss rates are too large to be powered by radiation pressure. The total kinetic energy ejected into the interstellar medium through mass loss during the WR phase of a massive star is estimated to be 7x1050 ergs, comparable to that of a supernova event.

Interacting stellar winds in a binary system

10.1017/s0252921100095208 ◽

1981 ◽

Vol 59 ◽

pp. 499-502

Author(s):

Sun Kwok

Keyword(s):

Binary System ◽

Mass Loss ◽

Stellar Winds ◽

Long Time ◽

Wind Velocities ◽

M Stars ◽

Hr Diagram ◽

It is now known that strong stellar winds develop in stars mostly at the red and blue sides of the HR diagram. However, although the mass loss rates observed in O and M stars are comparable, the corresponding wind velocities are vastly different. It would thus be of great interest to find a binary system, containing both a cool and a hot star each with its own wind, and observe the resultant interaction. For a long time, α Sco (M1.5 Iab + B2.5 V) was the only known example (Kudritzki and Reimers 1978, van der Hucht et al. 1980). The situation in this case is best illustrated by a VLA map made by Gibson (1979) who finds that a shock develops at the surface of interaction of the two winds. In this paper I shall describe another binary system in which two stellar winds are interacting with dramatic effects.

Wind properties of variable B supergiants

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731678 ◽

2018 ◽

Vol 614 ◽

pp. A91 ◽

Cited By ~ 3

Author(s):

M. Haucke ◽

L. S. Cidale ◽

R. O. J. Venero ◽

M. Curé ◽

M. Kraus ◽

...

Keyword(s):

Mass Loss ◽

Mass Loss Rate ◽

Empirical Relationship ◽

Variable Stars ◽

Stellar Winds ◽

Radial Pulsation ◽

Line Profiles ◽

Stellar Radius ◽

Wind Variability ◽

Context. Variable B supergiants (BSGs) constitute a heterogeneous group of stars with complex photometric and spectroscopic behaviours. They exhibit mass-loss variations and experience different types of oscillation modes, and there is growing evidence that variable stellar winds and photospheric pulsations are closely related. Aims. To discuss the wind properties and variability of evolved B-type stars, we derive new stellar and wind parameters for a sample of 19 Galactic BSGs by fitting theoretical line profiles of H, He, and Si to the observed ones and compare them with previous determinations. Methods. The synthetic line profiles are computed with the non-local thermodynamic equilibrium (NLTE) atmosphere code FASTWIND, with a β-law for hydrodynamics. Results. The mass-loss rate of three stars has been obtained for the first time. The global properties of stellar winds of mid/late B supergiants are well represented by a β-law with β > 2. All stars follow the known empirical wind momentum–luminosity relationships, and the late BSGs show the trend of the mid BSGs. HD 75149 and HD 99953 display significant changes in the shape and intensity of the Hα line (from a pure absorption to a P Cygni profile, and vice versa). These stars have mass-loss variations of almost a factor of 2.8. A comparison among mass-loss rates from the literature reveals discrepancies of a factor of 1 to 7. This large variation is a consequence of the uncertainties in the determination of the stellar radius. Therefore, for a reliable comparison of these values we used the invariant parameter Qr. Based on this parameter, we find an empirical relationship that associates the amplitude of mass-loss variations with photometric/spectroscopic variability on timescales of tens of days. We find that stars located on the cool side of the bi-stability jump show a decrease in the ratio V∞∕Vesc, while their corresponding mass-loss rates are similar to or lower than the values found for stars on the hot side. Particularly, for those variable stars a decrease in V∞∕Vesc is accompanied by a decrease in Ṁ. Conclusions. Our results also suggest that radial pulsation modes with periods longer than 6 days might be responsible for the wind variability in the mid/late-type. These radial modes might be identified with strange modes, which are known to facilitate (enhanced) mass loss. On the other hand, we propose that the wind behaviour of stars on the cool side of the bi-stability jump could fit with predictions of the δ−slow hydrodynamics solution for radiation-driven winds with highly variable ionization.