scholarly journals The Mass Loss Rate of SK 80 (07Iaf) in the Small Magellanic Cloud

1986 ◽  
Vol 116 ◽  
pp. 269-270
Author(s):  
A J Willis ◽  
I D Howarth ◽  
K Nandy ◽  
D H Morgan
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Optical Spectra ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Small Magellanic Cloud ◽  
Ob Stars

The star SK 80 in the SMC is classified as 07Iaf by Walborn (1976) who notes that it is the only confirmed Of star in that Galaxy known to date. A knowledge of the mass loss properties of OB stars in the Magellanic Clouds is of interest because of the recent evidence that such stars show reduced mass loss properties than their galactic counterparts (Hutchings 1980) and for Of stars because of the possible link between such stars and Pop I transition WNL stars (Conti 1976).We have secured HIRES IUE and optical spectra of SK 80 and have attempted to derive the mass loss rate from these data.

Mass‐Loss Rate and He/H Abundance of the Erupting Component in the Small Magellanic Cloud System HD 5980

1998 ◽  
Vol 499 (2) ◽  
pp. 889-897 ◽  
Author(s):  
G. Koenigsberger ◽  
M Pena ◽  
W. Schmutz ◽  
S. Ayala
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Magellanic Cloud ◽  
Cloud System ◽  
Small Magellanic Cloud

scholarly journals ISO Observations of AGB Stars in the Small Magellanic Cloud

1999 ◽  
Vol 192 ◽  
pp. 95-99
Author(s):  
J.A.D.L. Blommaert ◽  
M.A.T. Groenewegen ◽  
M. R. Cioni ◽  
H. J. Habing ◽  
J.Th. van Loon ◽  
...  
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Magellanic Cloud ◽  
Radiative Transfer Model ◽  
Spectral Energy ◽  
Transfer Model ◽  
Agb Stars ◽  
Small Magellanic Cloud

We used ISOCAM and ISOPHOT to observe the spectral energy distribution between 3.6 and 60 μm of AGB stars in the Small Magellanic Cloud detected by IRAS. CAM-CVF spectra are made which enable us to establish the carbon- or oxygen-rich nature of the stars.We are in the process of analysing this data using a radiative transfer model. This will provide us with accurate determinations of luminosity and mass loss rate. Combining the results on the SMC, LMC and Galaxy we hope to address the open question of the metallicity dependencies of the mass loss rate. This in turn is important in the ejection of matter by AGB stars into the interstellar medium.

scholarly journals Mass loss and evolution of massive stars in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 480-482 ◽  
Author(s):  
Claus Leitherer ◽  
Norbert Langer
Keyword(s):  
Mass Loss ◽  
Iterative Procedure ◽  
Metal Content ◽  
Loss Rate ◽  
Massive Stars ◽  
Mass Loss Rate ◽  
Magellanic Clouds ◽  
Evolutionary Models ◽  
Low Metallicity ◽  
Self Consistency

The structure and evolution of massive stars is significantly influenced by effects of chemical composition in a low-metallicity environment (as compared to the solar neighbourhood, SN), such as the Magellanic Clouds. A fundamental ingredient in evolutionary models is the stellar mass-loss rate M. Lower metal content decreases the mass-loss rates derived theoretically, which in turn affects the stellar evolution models. On the other hand, different evolutionary models predict different stellar parameters (especially L), which again influence M so that an iterative procedure is required to achieve self-consistency.

scholarly journals Red Giant Stars: Comparison of Observations and Theory

1984 ◽  
Vol 108 ◽  
pp. 195-206
Author(s):  
Jeremy Mould
Keyword(s):  
Mass Loss ◽  
Parameter Space ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Carbon Stars ◽  
Giant Stars ◽  
Theoretical Investigations ◽  
Red Giant

Recent observations in both the field and the clusters of the Magellanic Clouds suggest a higher mass loss rate during or at the end of the asymptotic giant branch phase than previously supposed. Recent theoretical investigations offer an explanation for the frequency of carbon stars in the Clouds, but a rich parameter space remains to be explored, before detailed agreement can be expected.

scholarly journals Evolution of 1–5 Mm⊙ Stars by Mass Loss

1993 ◽  
Vol 155 ◽  
pp. 478-478
Author(s):  
E. Vassiliadis ◽  
P.R. Wood
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Main Sequence ◽  
Mass Loss Rate ◽  
Star Clusters ◽  
Magellanic Clouds ◽  
Pulsation Period ◽  
Agb Stars ◽  
Loss Formula ◽  
Loss Rates

Stars of mass 1–5 MM⊙ and composition Y=0.25 and Z=0.016 have been evolved from the main-sequence to the white dwarf stage with an empirical mass loss formula based on observations of mass loss rates in AGB stars. This mass loss formula (Wood 1990) causes the mass loss rate to rise exponentially with pulsation period on the AGB until superwind rates are achieved, where these rates correspond to radiation pressure driven mass loss rates. The formula was designed to reproduce the maximum periods observed for optically-visible LPVs and it also reproduces extremely well the maximum AGB luminosities observed in star clusters in the Magellanic Clouds (see Vassiliadis and Wood 1992 for details).

scholarly journals The mass-loss, expansion velocities, and dust production rates of carbon stars in the Magellanic Clouds

2019 ◽  
Vol 487 (1) ◽  
pp. 502-521 ◽  
Author(s):  
Ambra Nanni ◽  
Martin A T Groenewegen ◽  
Bernhard Aringer ◽  
Stefano Rubele ◽  
Alessandro Bressan ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Loss Rate ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Spectral Energy ◽  
Carbon Stars ◽  
Dust Production ◽  
Production Rates ◽  
Total Dust

ABSTRACT The properties of carbon stars in the Magellanic Clouds (MCs) and their total dust production rates are predicted by fitting their spectral energy distributions (SED) over pre-computed grids of spectra reprocessed by dust. The grids are calculated as a function of the stellar parameters by consistently following the growth for several dust species in their circumstellar envelopes, coupled with a stationary wind. Dust radiative transfer is computed taking as input the results of the dust growth calculations. The optical constants for amorphous carbon are selected in order to reproduce different observations in the infrared and optical bands of Gaia Data Release 2. We find a tail of extreme mass-losing carbon stars in the Large Magellanic Cloud (LMC) with low gas-to-dust ratios that is not present in the Small Magellanic Cloud (SMC). Typical gas-to-dust ratios are around 700 for the extreme stars, but they can be down to ∼160–200 and ∼100 for a few sources in the SMC and in the LMC, respectively. The total dust production rate for the carbon star population is ∼1.77 ± 0.45 × 10−5 M⊙ yr−1, for the LMC, and ∼2.52 ± 0.96 × 10−6 M⊙ yr−1, for the SMC. The extreme carbon stars observed with the Atacama Large Millimeter Array and their wind speed are studied in detail. For the most dust-obscured star in this sample the estimated mass-loss rate is ∼6.3 × 10−5 M⊙ yr−1. The grids of spectra are available at:1 and included in the SED-fitting python package for fitting evolved stars.2

scholarly journals Mass loss rate determination of southern OB stars

2001 ◽  
Vol 372 (3) ◽  
pp. 952-962 ◽  
Author(s):  
P. Benaglia ◽  
C. E. Cappa ◽  
B. S. Koribalski
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Ob Stars

scholarly journals X-rays From Centrifugal Magnetospheres in Massive Stars

2014 ◽  
Vol 9 (S307) ◽  
pp. 449-450 ◽  
Author(s):  
Christopher Bard ◽  
Richard Townsend
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Massive Stars ◽  
Mass Loss Rate ◽  
X Rays ◽  
Stellar Rotation ◽  
Hydrodynamic Simulations ◽  
X Ray ◽  
Ob Stars ◽  
Magnetically Confined

AbstractIn the subset of massive OB stars with strong global magnetic fields, X-rays arise from magnetically confined wind shocks (Babel & Montmerle 1997). However, it is not yet clear what the effect of stellar rotation and mass-loss rate is on these wind shocks and resulting X-rays. Here, we present results from a grid of Arbitrary Rigid-Field Hydrodynamic simulations (ARFHD) of a B-star centrifugal magnetosphere with an eye towards quantifying the effect of stellar rotation and mass-loss rate on the level of X-ray emission. The results are also compared to a generalized XADM model for X-rays in dynamical magnetospheres (ud-Doula et al. 2014).

scholarly journals Global hot-star wind models for stars from Magellanic Clouds

2018 ◽  
Vol 612 ◽  
pp. A20 ◽  
Author(s):  
J. Krtička ◽  
J. Kubát
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Main Sequence ◽  
Mass Loss Rate ◽  
Magellanic Clouds ◽  
Line Profiles ◽  
Equilibrium Equations ◽  
Theoretical Predictions ◽  
Kinetic Equilibrium ◽  
Loss Rates

We provide mass-loss rate predictions for O stars from Large and Small Magellanic Clouds. We calculate global (unified, hydrodynamic) model atmospheres of main sequence, giant, and supergiant stars for chemical composition corresponding to Magellanic Clouds. The models solve radiative transfer equation in comoving frame, kinetic equilibrium equations (also known as NLTE equations), and hydrodynamical equations from (quasi-)hydrostatic atmosphere to expanding stellar wind. The models allow us to predict wind density, velocity, and temperature (consequently also the terminal wind velocity and the mass-loss rate) just from basic global stellar parameters. As a result of their lower metallicity, the line radiative driving is weaker leading to lower wind mass-loss rates with respect to the Galactic stars. We provide a formula that fits the mass-loss rate predicted by our models as a function of stellar luminosity and metallicity. On average, the mass-loss rate scales with metallicity as Ṁ ~ Z0.59. The predicted mass-loss rates are lower than mass-loss rates derived from Hα diagnostics and can be reconciled with observational results assuming clumping factor Cc = 9. On the other hand, the predicted mass-loss rates either agree or are slightly higher than the mass-loss rates derived from ultraviolet wind line profiles. The calculated P v ionization fractions also agree with values derived from observations for LMC stars with Teff ≤ 40 000 K. Taken together, our theoretical predictions provide reasonable models with consistent mass-loss rate determination, which can be used for quantitative study of stars from Magellanic Clouds.

scholarly journals Critical rates of stellar mass loss

1979 ◽  
Vol 83 ◽  
pp. 349-356 ◽  
Author(s):  
D. S. P. Dearborn ◽  
J. B. Blake
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Main Sequence ◽  
Mass Loss Rate ◽  
Critical Mass ◽  
Ob Stars ◽  
Average Mass ◽  
Original Mass ◽  
Moderate Mass ◽  
Rayet Star

Many of the effects of mass loss on OB stars have now been explored. Mass loss will cause a star to be overluminous for its mass (though less luminous than a star of its original mass) and, for moderate mass-loss rates, the luminosity decreases at the same rate as the mass contained in the convective core decreases causing the main sequence lifetime to remain unchanged (Chiosi and Nasi 1974, 1978, Deloore, DeGreve and Lamers 1977, Dearborn, Blake, Hainebach and Schramm 1978). Mass loss can also expose layers where 14N has been enhanced via the CNO tricyle (Dearborn and Eggleton 1977) and, in extreme cases, can produce a stripped helium core resembling a Wolf-Rayet Star (Hartwick 1967). While many of these phenomena (in particular the composition change) are more sensitive to the total mass removed than the formalism used to represent the mass loss, significant differences will result for the same average mass-loss rate depending on whether the mass was removed early (near the ZAMS), or late (near core hydrogen depletion). In addition, there appears to be a critical mass loss rate which depends on initial mass and separates those models which continue to evolve in a relatively normal (though subluminous) manner, and those models which evolve to a Wolf-Rayet configuration.

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