Mass Conservation and Rapid Mass Loss on the Main Sequence

1979 ◽  
pp. 375-382
Author(s):  
T. J. Mazurek
Keyword(s):  
Mass Loss ◽  
Main Sequence ◽  
Mass Conservation ◽  
Rapid Mass

scholarly journals Mass conservation and rapid mass loss on the main sequence

1979 ◽  
Vol 83 ◽  
pp. 375-377
Author(s):  
T. J. Mazurek
Keyword(s):  
Mass Loss ◽  
Flow Rate ◽  
Acoustic Waves ◽  
Main Sequence ◽  
Mass Conservation ◽  
Observational Evidence ◽  
Hydrogen Burning ◽  
Low Mass ◽  
Stellar Masses ◽  
Rapid Mass

The rapid mass loss observed in O stars can affect their evolution dramatically if it takes place during core hydrogen burning on the main sequence. Conti has suggested that this is the case for the brightest Of stars, and that these stars evolve into Wolf-Rayet (WR) stars. Support for this scenario comes from the similarity in the spectra of the Of and WR stars, and from the observed helium enrichment of Wolf-Rayet WN stars along with the correlation of the latter with the most luminous O stars. If the most massive Of stars evolve to WN stars of relatively low mass, one needs to determine the range of zero-age stellar masses where such an evolution occurs. This communication abstracts some observational evidence that bears on the question of the minimum zero-age mass for rapid mass loss on the main sequence. It then summarizes the author's investigation of a model for mass loss where photospheric acoustic waves control the flow rate.

scholarly journals On Stothers’ and Simon’s Binary-Star Hypothesis for Beta Canis Majoris Star Pulsation

1971 ◽  
Vol 15 ◽  
pp. 197-203
Author(s):  
John R. Percy ◽  
Katherine Madore
Keyword(s):  
Mass Loss ◽  
Binary Systems ◽  
Main Sequence ◽  
Binary Star ◽  
Variable Stars ◽  
Pulsating Variable Stars ◽  
Short Period ◽  
Massive Binary Systems ◽  
Radial Pulsations ◽  
Rapid Mass

The β CMa stars are short-period pulsating variable stars lying slightly above the upper main sequence. Although they have been known and studied for 70 years, little is known about the nature and cause of their pulsation.STOTHERS and SIMON (1969) have recently advanced an hypothesis – hereinafter known as the hypothesis – which proposes that all β CMa stars are the former secondary components of massive binary systems. The former primary components, being more massive, have evolved first, have shed their envelopes by rapid mass loss, and have deposited helium-enriched material from their cores upon the surfaces of the secondary components. This causes the secondary components (now the primary components) to become unstable, via the so-called „μ-mechanism“, to nuclear-energized radial pulsations.

scholarly journals Mass-loss varying luminosity and its implication to the solar evolution

2019 ◽  
Vol 15 (S356) ◽  
pp. 403-404
Author(s):  
Negessa Tilahun Shukure ◽  
Solomon Belay Tessema ◽  
Endalkachew Mengistu
Keyword(s):  
Standard Model ◽  
Mass Loss ◽  
Main Sequence ◽  
The Sun ◽  
Solar Mass ◽  
Solar Luminosity ◽  
Solar Evolution

AbstractSeveral models of the solar luminosity, , in the evolutionary timescale, have been computed as a function of time. However, the solar mass-loss, , is one of the drivers of variation in this timescale. The purpose of this study is to model mass-loss varying solar luminosity, , and to predict the luminosity variation before it leaves the main sequence. We numerically computed the up to 4.9 Gyrs from now. We used the solution to compute the modeled . We then validated our model with the current solar standard model (SSM). The shows consistency up to 8 Gyrs. At about 8.85 Gyrs, the Sun loses 28% of its mass and its luminosity increased to 2.2. The model suggests that the total main sequence lifetime is nearly 9 Gyrs. The model explains well the stage at which the Sun exhausts its central supply of hydrogen and when it will be ready to leave the main sequence. It may also explain the fate of the Sun by making some improvements in comparison to previous models.

scholarly journals Discovery of Infrared Stars in Globular Clusters in the Magellanic Clouds and Their Light Variations

1998 ◽  
Vol 11 (1) ◽  
pp. 395-395
Author(s):  
S. Nishida ◽  
T. Tanabé ◽  
S. Matsumoto ◽  
T. Onaka ◽  
Y. Nakada ◽  
...  
Keyword(s):  
Mass Loss ◽  
Globular Clusters ◽  
Main Sequence ◽  
Near Infrared ◽  
Magellanic Clouds ◽  
Infrared Light ◽  
Agb Stars ◽  
Dust Shells ◽  
Infrared Stars ◽  
Infrared Survey

A systematic near-infrared survey was made for globular clusters in the Magellanic Clouds. Two infrared stars were discovered in NGC419 (SMC) and NGC1783 (LMC). NGC419 and NGC1783 are well-studied rich globular clusters whose turn-off masses and ages are estimated MTO ~ 2.0 Mʘ and т ~1.2 Gyr for NGC419, and MT0 ~ 2.0 Mʘ and т ʘ 0.9 Gyr for NGC1783, respectively. The periods of the infrared light variations were determined to be 540 dfor NGC419IR1 and to be 480 d for NGC1783IR1, respectively. Comparison of the measurements with the period—if magnitude relation for carbon Miras in the LMC by Groenewegen and Whitelock(1996) revealed that the Kmagnitudes of the infrared stars were fainter by about 0.3 — 0.8 magnitude than those predicted by the P — K relation. This deviation can be explained if the infrared stars are surrounded by thick dust shells and are obscured even in the K band. The positions of NGC419IR1and NGC1783IR1 on the P — K diagram suggest that AGB stars with the main sequence masses of about 2 Mʘ start their heavy mass-loss when P ʘ 500 d.

scholarly journals Glacier Surface Mass Balance in the Suntar-Khayata Mountains, Northeastern Siberia

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1949 ◽  
Author(s):  
Yong Zhang ◽  
Xin Wang ◽  
Zongli Jiang ◽  
Junfeng Wei ◽  
Hiroyuki Enomoto ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Surface Mass Balance ◽  
Negative Mass ◽  
Glacier Surface ◽  
Surface Mass ◽  
Northeastern Siberia ◽  
Response To Temperature ◽  
Rapid Mass

Arctic glaciers comprise a small fraction of the world’s land ice area, but their ongoing mass loss currently represents a large cryospheric contribution to the sea level rise. In the Suntar-Khayata Mountains (SKMs) of northeastern Siberia, in situ measurements of glacier surface mass balance (SMB) are relatively sparse, limiting our understanding of the spatiotemporal patterns of regional mass loss. Here, we present SMB time series for all glaciers in the SKMs, estimated through a glacier SMB model. Our results yielded an average SMB of −0.22 m water equivalents (w.e.) year−1 for the whole region during 1951–2011. We found that 77.4% of these glaciers had a negative mass balance and detected slightly negative mass balance prior to 1991 and significantly rapid mass loss since 1991. The analysis suggests that the rapidly accelerating mass loss was dominated by increased surface melting, while the importance of refreezing in the SMB progressively decreased over time. Projections under two future climate scenarios confirmed the sustained rapid shrinkage of these glaciers. In response to temperature rise, the total present glacier area is likely to decrease by around 50% during the period 2071–2100 under representative concentration pathway 8.5 (RCP8.5).

scholarly journals The VLT-FLAMES Tarantula Survey

2016 ◽  
Vol 12 (S329) ◽  
pp. 279-286
Author(s):  
Jorick S. Vink ◽  
C.J. Evans ◽  
J. Bestenlehner ◽  
C. McEvoy ◽  
O. Ramírez-Agudelo ◽  
...  
Keyword(s):  
Mass Loss ◽  
Main Sequence ◽  
Massive Stars ◽  
Mass Function ◽  
Large Magellanic Cloud ◽  
Initial Mass Function ◽  
Data Set ◽  
Large Program ◽  
Medium Resolution ◽  
Key Questions

AbstractWe present a number of notable results from the VLT-FLAMES Tarantula Survey (VFTS), an ESO Large Program during which we obtained multi-epoch medium-resolution optical spectroscopy of a very large sample of over 800 massive stars in the 30 Doradus region of the Large Magellanic Cloud (LMC). This unprecedented data-set has enabled us to address some key questions regarding atmospheres and winds, as well as the evolution of (very) massive stars. Here we focus on O-type runaways, the width of the main sequence, and the mass-loss rates for (very) massive stars. We also provide indications for the presence of a top-heavy initial mass function (IMF) in 30 Dor.

scholarly journals Theoretical mass loss rates of cool main-sequence stars

2006 ◽  
Vol 463 (1) ◽  
pp. 11-21 ◽  
Author(s):  
V. Holzwarth ◽  
M. Jardine
Keyword(s):  
Mass Loss ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Theoretical Mass ◽  
Loss Rates

scholarly journals Rapid mass loss and disappearance of summer-accumulation type hanging glacier

2021 ◽  
Author(s):  
X.U. Chun-hai ◽  
L.I. Zhong-qin ◽  
W.A.N.G. Fei-teng ◽  
W.A.N.G. Pu-yu ◽  
M.U. Jian-xin
Keyword(s):  
Mass Loss ◽  
Rapid Mass

scholarly journals Modelling Time-Dependent Diffusion in Am Star Envelopes

1993 ◽  
Vol 137 ◽  
pp. 272-274 ◽  
Author(s):  
G. Alecian
Keyword(s):  
Diffusion Process ◽  
Mass Loss ◽  
Main Sequence ◽  
Convection Zone ◽  
Time Dependent ◽  
Radiative Zone

AbstractWe study the diffusion process occurring just below the superficial convection zone of Am stars, improving the methods used sofar. We are now able to compute, in a more realistic way, the evolution of the concentrations during the stay of the stars on the main sequence for a large number of elements. This allows to better constrain the different properties (mass loss, depth of the superficial convection zone, transition between convection and radiative zone) entering the modelling of Am stars in the framework of a diffusion-dominant description.

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