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

This work focuses broadly on individual, live shrubs and, more specifically, it examines bulk density in chaparral and its combined effects with wind and ignition location on the resulting fire behaviour. Empirical functions to predict bulk density as a function of height for 4-year-old chaparral were developed for two typical species of shrub fuels in southern California, USA, namely chamise (Adenostoma fasciculatum Hook & Arn.) and manzanita (Arctostaphylos spp. Adans.). Fuel beds of chamise foliage and small-diameter branches were burned in an open-topped wind tunnel. Three levels of bulk density, two ignition locations and two wind speeds were examined, focusing on overall fire behaviour. Mean maximum mass loss rate, elapsed time at which maximum mass loss rate occurred, flame height, flame angle, peak gas temperature and its peak change rate were measured. The mean maximum mass loss rate was not significantly affected by wind speed, ignition location, bulk density or moisture content. Both wind speed and ignition location significantly affected the time that maximum mass loss rate occurred. Only wind speed affected flame height and flame angle. The peak gas temperature within the shrub burning area was found to be mostly affected by the bulk density.

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A New Evolutionary Interpretation of the IRAS Two-Colour Diagram

Symposium - International Astronomical Union ◽

10.1017/s0074180900171219 ◽

1993 ◽

Vol 155 ◽

pp. 332-332 ◽

Cited By ~ 1

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.

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OH masers in oxygen-rich late-type stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900222626 ◽

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.

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The estimate of hot Jupiter mass loss rate in the interaction with CME from a solar type star

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316000089 ◽

2015 ◽

Vol 11 (S320) ◽

pp. 224-229

Author(s):

Dmitry V. Bisikalo ◽

Alexander A. Cherenkov ◽

Pavel V. Kaygorodov

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Type Star ◽

Dynamic Simulations ◽

Solar Type ◽

Mass Ejection ◽

Maximum Mass Loss ◽

Solar Type Star ◽

Hot Jupiter

AbstractWe consider the influence of a coronal mass ejection (CME) of a solar type star on the mass loss rate of a hot Jupiter exoplanet. We have conducted 3D numerical gas-dynamic simulations of the planet's atmosphere that interacts with CME. Using the results of these simulations we have estimated the specific parameters that influence the mass loss rate. Based on the assumption that CME totally sweeps away part of the planet's gaseous envelope located outside the Roche lobe we estimated the maximum mass loss rate. Finally, we have considered the dependence of mass loss rate on the frequency of CMEs in course of star's evolution.

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

Symposium - International Astronomical Union ◽

10.1017/s0074180900094304 ◽

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.

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AGB mass loss

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312010721 ◽

2011 ◽

Vol 7 (S283) ◽

pp. 71-78

Author(s):

Lee A. Willson ◽

Qian Wang

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Central Star ◽

Constant Mass ◽

Single Star ◽

The Core ◽

Maximum Mass Loss ◽

Loss Formula ◽

Remnant Mass

AbstractMass loss on the AGB removes most of the envelope and leaves a compact remnant to become a white dwarf and perhaps first the central star of a planetary nebula. The envelope mass provides an upper limit on the material available to form the PN, and the terminal mass loss rate plus the small remnant mass left on the core determines how much of that would still be available to form the PN after the star has evolved far enough to the blue. Given a mass loss formula based on observations or models, we can find the deathline where −dMstar/dt = (M/L) dL/dt and can find the contours of constant mass loss rate on a plot of M vs. L. From such plots we can derive the mass available for a PN and the lowest mass single star that can produce a PN of a given mass. However, some details important for PN formation remain uncertain, including the maximum mass loss rate achieved and the envelope mass left when AGB mass loss ceases.

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Evolution and Mass Loss of Cool Aging Stars: A Daedalean Story

Annual Review of Astronomy and Astrophysics ◽

10.1146/annurev-astro-090120-033712 ◽

2021 ◽

Vol 59 (1) ◽

Author(s):

Leen Decin

Keyword(s):

Mass Loss ◽

Stellar Evolution ◽

Loss Rate ◽

Mass Loss Rate ◽

Binary Interaction ◽

Annual Review ◽

Publication Date ◽

Driving Mechanism ◽

Chemical Enrichment ◽

Dust Seeds

A multitude of phenomena—such as the chemical enrichment of the Universe, the mass spectrum of planetary nebulae, white dwarfs and gravitational wave progenitors, the frequency distribution of supernovae, the fate of exoplanets, etc.—are highly regulated by the amounts of mass that stars expel through a powerful wind. For more than half a century, these winds of cool aging stars have been interpreted within the common interpretive framework of 1D models. I here discuss how that framework now appears to be highly problematic. • Current 1D mass-loss rate formulae differ by orders of magnitude, rendering contemporary stellar evolution predictions highly uncertain. These stellar winds harbor 3D complexities that bridge 23 orders of magnitude in scale, ranging from the nanometer up to thousands of astronomical units. We need to embrace and understand these 3D spatial realities if we aim to quantify mass loss and assess its effect on stellar evolution. We therefore need to gauge the following: • The 3D life of molecules and solid-state aggregates: The gas-phase clusters that form the first dust seeds are not yet identified. This limits our ability to predict mass-loss rates using a self-consistent approach. • The emergence of 3D clumps: They contribute in a nonnegligible way to the mass loss, although they seem of limited importance for the wind-driving mechanism. • The 3D lasting impact of a (hidden) companion: Unrecognized binary interaction has biased previous mass-loss rate estimates toward values that are too large. Only then will it be possible to drastically improve our predictive power of the evolutionary path in 4D (classical) spacetime of any star. Expected final online publication date for the Annual Review of Astronomy and Astrophysics, Volume 59 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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