scholarly journals A New Evolutionary Interpretation of the IRAS Two-Colour Diagram

1993 ◽  
Vol 155 ◽  
pp. 332-332 ◽  
Author(s):  
P. García-Lario ◽  
A. Manchado ◽  
S.R. Pottasch
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Theoretical Models ◽  
Initial Mass ◽  
Type I ◽  
Processed Material ◽  
Ir Stars ◽  
Image Position ◽  
Evolutionary Interpretation

A new evolutionary interpretation of the sequence of colours observed in the IRAS two-colour diagram by AGB and post-AGB stars is given, which is capable of explaining the observational properties of both kind of objects. It is useful to define a parameter λ to define the position of a given star in this “infrared main sequence” (IRMS). Adopting and from the analysis of the expansion velocities, mass loss rates and luminosities observed in a selected sample of non-variable OH/IR stars with no optical counterpart in the Galactic bulge as a function of λ, we conclude that the position in the IRAS two-colour diagram at which a star leaves the IRMS (λmax) only depends on the initial mass Mz of the progenitor star, so that only massive objects can reach the upper end of this sequence. The relation found is: Expansion velocities increase with the initial mass while every point in the IRMS is found to be associated to a certain value of the mass loss rate. This model also predicts the evolution with time of the mass loss rate during the AGB as a function of the initial mass of the progenitor star, and confirms that most known planetary nebulae are the result of the evolution of considerably massive stars (between 2–3 solar masses) which means that the contribution of processed material to the interstellar medium is considerably higher than what theoretical models predict. Type I PNe are the result of the evolution of 3 — 5 M⊙ progenitors while progenitors with Mi ≤ 1.2 M⊙ probably do not give PNe. The model is also in agreement with the narrow distribution of core masses found in central stars of PNe and white dwarfs and with the usual expansion velocities found in OH/IR stars.

scholarly journals Author Correction: Reduction of the maximum mass-loss rate of OH/IR stars due to unnoticed binary interaction

2019 ◽  
Vol 3 (5) ◽  
pp. 462-462
Author(s):  
L. Decin ◽  
W. Homan ◽  
T. Danilovich ◽  
A. de Koter ◽  
D. Engels ◽  
...  
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Binary Interaction ◽  
Maximum Mass ◽  
Ir Stars ◽  
Maximum Mass Loss

scholarly journals Influence of the Stellar Winds on the Evolution of the Planetary Nebula Nuclei

1993 ◽  
Vol 155 ◽  
pp. 483-483
Author(s):  
S.K. Górny
Keyword(s):  
Mass Loss ◽  
Planetary Nebula ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Stellar Winds ◽  
Hydrogen Burning ◽  
Wind Theory ◽  
Homogeneous Models ◽  
Image Position ◽  
Zero Points

A grid of homogeneous models of evolution of hydrogen burning planetary nebulae nuclei, assuming different stellar winds and the zero points for the post-AGB evolution, have been constructed from original Schönberners tracks. Following a simplified line-driven wind theory the mass loss rate has been adopted to be

scholarly journals OH masers in oxygen-rich late-type stars

2002 ◽  
Vol 206 ◽  
pp. 319-322
Author(s):  
Sandra Etoka ◽  
A.M. Le Squeren
Keyword(s):  
Mass Loss ◽  
Radio Telescope ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Monitoring Programme ◽  
Late Type ◽  
Wide Range ◽  
Ir Stars ◽  
Circumstellar Shell

We present here some noteworthy results of two related studies on oxygen-rich late type stars. The aim of this work was to study the OH circumstellar shell properties in terms of evolution. These studies are based on an OH monitoring programme carried out with the Nançay Radio Telescope. The first study concerns seven Miras distributed along the colour-colour diagram. They were observed at two or three different epochs covering one to seven cycles over a period from 1980 to 1995 at 1612, 1667 and 1665 MHz in both circular polarizations. The second study concerns thirty objects covering a wide range of mass loss rate from Miras to OH/IR stars. They were observed in 1994 at 1665 & 1667 MHz in both circular polarizations.

scholarly journals Mass loss from pulsating cool stars

2008 ◽  
Vol 4 (S252) ◽  
pp. 259-260
Author(s):  
Qian Wang ◽  
Lee Anne Willson ◽  
Steven Kawaler
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Evolutionary Model ◽  
Theoretical Models ◽  
Observation Data ◽  
Loss Mechanism ◽  
Model Calculations ◽  
Cool Stars ◽  
Evolutionary Studies

AbstractIt has long been clear that most, if not all, of the mass loss experienced by stars from 0.8 to 8 solar masses occurs near the tip of the AGB and/or the RGB. Evolutionary studies have incorporated empirical mass loss laws but theoretical models suggest quite different dependence of mass loss rate on stellar parameters. We are combining evolutionary model calculations with ISUEVO with mass loss modeling using the Bowen code in a systematic study of final stages of stellar evolution. We mapped the RGB (without steady mass loss) to the “Death Zone” as a function of mixing length, mass, and metallicity. We compared these results with observation data from Origlia. We are investigating a possible mass loss mechanism through companions as a complement to mass loss through pulsation. By the end of the project we expect to provide a reliable prescription for AGB mass loss.

scholarly journals The Maser Strength of OH/IR Stars, the Evolution of Mass loss and the Formation of a Planetary Nebula

1983 ◽  
Vol 103 ◽  
pp. 530-530
Author(s):  
B. Baud ◽  
H. J. Habing
Keyword(s):  
Mass Loss ◽  
Planetary Nebula ◽  
Loss Rate ◽  
Large Range ◽  
Mass Loss Rate ◽  
Asymptotic Giant Branch ◽  
Expansion Velocity ◽  
Simple Modification ◽  
Ir Stars ◽  
Circumstellar Shell

From observations we find that the OH luminosity LOH of an OH/IR star increases with R2, where R is the size of the masing region. From this correlation we deduce that the mass loss rate M, the expansion velocity ve and LOH are related by LOH ~(M/ve)2. Next we consider the large range that is observed in LOH and the steep OH luminosity distribution for OH/IR stars. Both facts can be explained by the postulate that these objects undergo accelerated mass loss, and thus steadily increase their OH luminosity. We propose that OH/IR stars are at the extreme end of the Asymptotic Giant Branch and that many of them are in the process of blowing off their entire envelope in a superwind phase. Their mass loss rate during this superwind, as deduced from OH observations of the circumstellar shell, is given by a simple modification of the Reimers equation. This modification connects the superwind continuously to the Reimers wind and it provides observational evidence for the formation of a planetary nebula.

scholarly journals Red Supergiant Stars as Supernova Progenitors – the X-ray Perspective

2015 ◽  
Vol 11 (A29B) ◽  
pp. 450-451
Author(s):  
Vikram V. Dwarkadas
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
High Mass ◽  
Initial Mass ◽  
X Ray ◽  
High Mass Loss ◽  
Red Supergiants ◽  
Low X

AbstractRed Supergiants (RSGs) have for decades been assumed to be the progenitors of Type IIP supernovae (SNe). They are expected to have dense winds with mass-loss rates up to 10−4 M⊙ yr−1. We have created a database of available X-ray lightcurves of SNe. Type IIP SNe are found to have the lowest X-ray luminosities among all classes, which is surprising given the high mass-loss rate winds expected from their red supergiant progenitors, and therefore the high density medium into which Type IIP SNe are expected to expand into. We show that the low X-ray luminosity sets a limit on the mass-loss rate of the progenitor star which can collapse to become a RSG, which is about 10−5 M⊙ yr−1. This in turn can be used to set a limit on the initial mass of a RSG star which can become a Type IIP progenitor, which is about 19 M⊙. This is consistent with the limit obtained via direct optical progenitor identification. Optically identified progenitors of Type IIP SNe are found to be RSGs with masses less than about 17 M⊙ (Smartt (2009)). We discuss the implications of this result for stellar evolution, theorize on the fate of RSG stars with initial mass > 19 M⊙, and discuss what type of SNe they will produce at the end of their lifetime.

WATER ICE IN HIGH MASS-LOSS RATE OH/IR STARS

2012 ◽  
Vol 762 (2) ◽  
pp. 113 ◽  
Author(s):  
Kyung-Won Suh ◽  
Young-Joo Kwon
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
High Mass ◽  
Water Ice ◽  
Ir Stars ◽  
High Mass Loss

scholarly journals Reduction of the maximum mass-loss rate of OH/IR stars due to unnoticed binary interaction

2019 ◽  
Vol 3 (5) ◽  
pp. 408-415 ◽  
Author(s):  
L. Decin ◽  
W. Homan ◽  
T. Danilovich ◽  
A. de Koter ◽  
D. Engels ◽  
...  
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Binary Interaction ◽  
Maximum Mass ◽  
Ir Stars ◽  
Maximum Mass Loss

Litter mass-loss rates in late stages of decomposition at some climatically and nutritionally different pine sites. Long-term decomposition in a Scots pine forest. VIII

1993 ◽  
Vol 71 (5) ◽  
pp. 680-692 ◽  
Author(s):  
Björn Berg ◽  
Charles McClaugherty ◽  
Maj-Britt Johansson
Keyword(s):  
Mass Loss ◽  
Scots Pine ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Climatic Conditions ◽  
Initial Mass ◽  
Lignin Concentration ◽  
Litter Mass ◽  
Litter Mass Loss ◽  
Loss Rates

The patterns of some chemical changes and litter mass-loss rates were investigated for a variety of types of decomposing litter in pine forests under different climatic conditions and at sites with different nutrient status. A mixed deciduous forest was also compared. In initially chemically identical Scots pine needle litter incubated under different climatic conditions, the lignin concentration increased faster as a function of accumulated mass loss when the climatic conditions promoted a higher initial mass-loss rate. Also under artificially created conditions, e.g., after fertilization and irrigation, the same phenomenon occurred. Litter mass-loss rates decreased during decomposition as lignin concentrations increased. The relative decrease was significantly larger at sites with a climate that promoted an initially higher mass-loss rate. At the same lignin concentration, however, the mass-loss rate was significantly lower in drier and colder conditions, viz. climatic conditions that promote a lower initial mass-loss rate. Nevertheless, at very high lignin concentrations that lignin clearly dominated over climate as a rate-regulating factor. A possible consequence of this observation could be a higher rate of organic matter accumulation at sites that initially promote a high initial mass-loss rate for litter than at sites with conditions that give lower initial rates, at least for a given species of litter. Key words: litter, decomposition, lignin, chemical changes, climatic transect, effect of climate change.

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