scholarly journals The Mass Loss Rate — Period Relation in Carbon Miras

1995 ◽  
Vol 155 ◽  
pp. 141-142
Author(s):  
Martin Groenewegen
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Linear Relation ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Pulsation Period ◽  
Sudden Increase ◽  
Period Relation ◽  
Dust Mass ◽  
Rate Period

AbstractThe relation between mass loss rate and pulsation period in carbon Miras is discussed. The dust mass loss rate is very low (about 2 10−10 M⊙yr) up to about P = 380 days, where there is a sudden increase. For P > 400 days there is a linear relation between log and P. The change in the mass loss rate near 380 days may be related to radiation pressure on dust becoming effective in driving the outflow.

scholarly journals Interplay between pulsation, mass loss, and third dredge-up: More about Miras with and without technetium

2019 ◽  
Vol 622 ◽  
pp. A120 ◽  
Author(s):  
S. Uttenthaler ◽  
I. McDonald ◽  
K. Bernhard ◽  
S. Cristallo ◽  
D. Gobrecht
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Pulsation Period ◽  
Mira Variables ◽  
Previous Sample ◽  
Ir Photometry ◽  
Good Probe ◽  
Loss Rates

Context. We follow-up on a previous finding that AGB Mira variables containing the third dredge-up indicator technetium (Tc) in their atmosphere form a different sequence of K − [22] colour as a function of pulsation period than Miras without Tc. A near- to mid-infrared colour such as K − [22] is a good probe for the dust mass-loss rate of the stars. Contrary to what might be expected, Tc-poor Miras show redder K − [22] colours (i.e. higher dust mass-loss rates) than Tc-rich Miras at a given period. Aims. Here, the previous sample is extended and the analysis is expanded towards other colours and dust spectra. The most important aim is to investigate if the same two sequences can be revealed in the gas mass-loss rate. Methods. We analysed new optical spectra and expanded the sample by including more stars from the literature. Near- and mid-IR photometry and ISO dust spectra of our stars were investigated where available. Literature data of gas mass-loss rates of Miras and semi-regular variables were collected and analysed. Results. Our results show that Tc-poor Miras are redder than Tc-rich Miras in a broad range of the mid-IR, suggesting that the previous finding based on the K − [22] colour is not due to a specific dust feature in the 22 μm band. We establish a linear relation between K − [22] and the gas mass-loss rate. We also find that the 13 μm feature disappears above K − [22]≃2.17 mag, corresponding to Ṁg ∼ 2.6 × 10−7 M⊙ yr−1. No similar sequences of Tc-poor and Tc-rich Miras in the gas mass-loss rate vs. period diagram are found, most probably owing to limitations in the available data. Conclusions. Different hypotheses to explain the observation of two sequences in the P vs. K − [22] diagram are discussed and tested, but so far, none of them convincingly explains the observations. Nevertheless, we might have found an hitherto unknown but potentially important process influencing mass loss on the TP-AGB.

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).

Does 3rd dredge-up reduce AGB mass-loss?

2018 ◽  
Vol 14 (S343) ◽  
pp. 529-530
Author(s):  
Stefan Uttenthaler ◽  
Iain McDonald ◽  
Klaus Bernhard ◽  
Sergio Cristallo ◽  
David Gobrecht
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Pulsation Period ◽  
Agb Stars ◽  
Mid Infrared ◽  
The Third ◽  
Previous Sample ◽  
Good Probe

AbstractWe follow up on a previous finding that Miras containing the third dredge-up (3DUP) indicator technetium (Tc) in their atmosphere form a different sequence of K – [22] colour as a function of pulsation period than Miras without Tc. A near-to-mid-infrared colour such as K – [22] is a good probe for the dust mass-loss rate (MLR) of these AGB stars. Contrary to what one might naïvely expect, Tc-poor Miras show redderK – [22] colours (i.e. higher dust MLRs) than Tc-rich Miras at a given period. In the follow-up work, the previous sample is extended and the analysis is expanded towards other colours and ISO dust spectra to check if the previous finding is due to a specific dust feature in the 22 μm band. We also investigate if the same two sequences can be revealed in the gas MLR. Different hypotheses to explain the observation of two sequences in the P vs. K – [22] diagram are discussed and tested, but so far none of them convincingly explains the observations.

Mass flow and evolution of UW Canis Majoris

1979 ◽  
Vol 83 ◽  
pp. 281-286
Author(s):  
Yoji Kondo ◽  
George E. McCluskey ◽  
Jürgen Rahe
Keyword(s):  
Mass Loss ◽  
Mass Flow ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Primary Component ◽  
Uv Spectrum ◽  
Solar Mass ◽  
Eclipsing Binary

The far-UV spectrum of the eclipsing binary UW CMa (O7f + O-B) had earlier been utilized to derive a mass-loss rate of about 10−6 to 10−5 solar mass per year. The mass flow seems to be basically in the form of a stellar wind emanating from the O7f primary component, with radiation pressure as the controlling factor. The main characteristics that make UW CMa a possible progenitor of a Wolf-Rayet system are discussed.

scholarly journals Mass loss from metal-poor stars

1981 ◽  
Vol 59 ◽  
pp. 297-300
Author(s):  
C. Chiosi ◽  
G. Bertelli ◽  
E. Nasi ◽  
L. Greggio
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Loss Rate ◽  
Massive Stars ◽  
Mass Loss Rate ◽  
Rate Relationship ◽  
Effective Temperatures ◽  
Hr Diagram ◽  
Pressure Driven

1. IntroductionIt is essential to consider the effect of mass loss to understand the distribution of supergiant stars in the HR diagram. This research concerns the evolution of massive stars with X=0.700 and Z=0.001 during the phases up to central Heexhaustion with the inclusion of mass loss. Such low value of Z has been chosen in order to allow a comparison with the supergiant stars of SMC. The rate of mass loss is formulated as in Chiosi, Nasi and Sreenivasan (1978). More specifically, in the range of high effective temperatures, we adopt the mass-loss rate relationship for radiation pressure driven wind of Castor, Abbott and Klein (1975), whereas in the range of low effective temperatures we assume the mass loss rate to be driven by the acoustic flux mechanism of Fusi Pecci and Renzini (1975).

scholarly journals Winds from Cataclysmic Variables

1997 ◽  
Vol 163 ◽  
pp. 465-474
Author(s):  
J. E. Drew
Keyword(s):  
Boundary Layer ◽  
Mass Loss ◽  
Radiation Pressure ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Cataclysmic Variables ◽  
Recent Developments ◽  
Orbital Phase ◽  
The Impact

AbstractThe winds associated with high states of non-magnetic (diskaccreting) cataclysmic variables are described and discussed. A quick summary of the basic phenomenology is given, and followed by a presentation of some of the more important recent developments in our understanding. The near-ubiquity of orbital-phase linked variability of the UV resonance lines (generally thought of as mainly wind-produced) is noted and its implications are considered. The impact of the much lower-thanexpected boundary layer luminosity upon mass loss rate determinations is also discussed. Current work on the role of radiation pressure (mediated by line opacity) is placed in context.

scholarly journals The wind of P Cygni

1989 ◽  
Vol 113 ◽  
pp. 259-260
Author(s):  
J. Puls ◽  
A.W.A. Pauldrach ◽  
R.P. Kudritzki
Keyword(s):  
Energy Distribution ◽  
Mass Loss ◽  
Radiation Pressure ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Terminal Velocity ◽  
Scaling Relations ◽  
Self Consistent ◽  
Line Pressure ◽  
Eddington Limit

The stationary features of the wind of P Cygni are considerably different from those of ‘normal’ supergiant winds with comparable luminosity. In contrast to such winds, which are generally accepted to be driven by radiation pressure, P Cygni’s mass-loss rate is higher by a factor of 5, the terminal velocity is higher by a factor of 10, and the velocity law itself is much flatter than would be expected from a first glance at glance at typical scaling relations. However, these relations depend crucially and non-linearly on the star’s distance from the Eddington limit, which for P Cyg is very small (see below). Here we investigate whether the acceleration mechanism of P Cygni’s wind can also be explained by line pressure and to what extent self-consistent wind models represent the observed quantities (especially the IR energy distribution).

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