The point on the theoretical changes of surface chemistry during massive star evolution

2006 ◽  
pp. 79-85
Author(s):  
André Maeder
Keyword(s):  
Surface Chemistry ◽  
Massive Star ◽  
Star Evolution ◽  
Massive Star Evolution

scholarly journals The Point on the Theoretical Changes of Surface Chemistry During Massive Star Evolution

1988 ◽  
Vol 108 ◽  
pp. 79-85
Author(s):  
André Maeder
Keyword(s):  
Surface Chemistry ◽  
Cross Sections ◽  
Massive Star ◽  
Main Sequence ◽  
Tidal Mixing ◽  
Main Sequence Stars ◽  
Star Evolution ◽  
Cno Abundances ◽  
Massive Star Evolution ◽  
Nuclear Processing

For main sequence stars, the central nuclear processing generally has no effect on surface abundances. Later in the evolution, the newly synthetized elements may be revealed at the stellar surface by processes such as mass loss, convective dredge-up, overshooting, diffusion, rotational and tidal mixing, etc. The changes of CNO abundances are the most conspicuous and the easiest to observe spectroscopically; some abundance ratios like C/N, O/N may undergo changes by more than 102. On the whole, surface chemistry is a most powerful diagnostics of stellar evolution, model assumptions and nuclear cross sections.

scholarly journals Outflowing Envelopes From Stars at Arbitrary Optical Depths a New Approach to the Problem

1998 ◽  
Vol 11 (1) ◽  
pp. 381-381
Author(s):  
A.V. Dorodnitsyn
Keyword(s):  
Differential Equations ◽  
Massive Star ◽  
System Of Differential Equations ◽  
Continuous Transition ◽  
Satisfactory Description ◽  
Sonic Point ◽  
New Approach ◽  
Star Evolution ◽  
Matter Flux ◽  
Massive Star Evolution

We have considered a stationary outflowing envelope accelerated by the radiative force in arbitrary optical depth case. Introduced approximations provide satisfactory description of the behavior of the matter flux with partially separated radiation at arbitrary optical depths. The obtained systemof differential equations provides a continuous transition of the solution between optically thin and optically thick regions. We analytically derivedapproximate representation of the solution at the vicinity of the sonic point. Using this representation we numerically integrate the system of equations from the critical point to the infinity. Matching the boundary conditions we obtain solutions describing the problem system of differential equations. The theoretical approach advanced in this work could be useful for self-consistent simulations of massive star evolution with mass loss.

scholarly journals Four open questions in massive star evolution

2013 ◽  
Vol 63 ◽  
pp. 373-383 ◽  
Author(s):  
G. Meynet ◽  
P. Eggenberger ◽  
S. Ekström ◽  
C. Georgy ◽  
J. Groh ◽  
...  
Keyword(s):  
Massive Star ◽  
Star Evolution ◽  
Open Questions ◽  
Massive Star Evolution

scholarly journals The Final Months of Massive Star Evolution from the Circumstellar Environment around SN Ic 2020oi

2021 ◽  
Vol 918 (1) ◽  
pp. 34
Author(s):  
Keiichi Maeda ◽  
Poonam Chandra ◽  
Tomoki Matsuoka ◽  
Stuart Ryder ◽  
Takashi J. Moriya ◽  
...  
Keyword(s):  
Massive Star ◽  
Star Evolution ◽  
Massive Star Evolution ◽  
Circumstellar Environment

scholarly journals DDO68-V1: an extremely metal-poor LBV in a void galaxy

2018 ◽  
Vol 14 (S344) ◽  
pp. 392-395
Author(s):  
Yulia Perepelitsyna ◽  
Simon Pustilnik
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
Rare Event ◽  
Local Universe ◽  
Hii Region ◽  
V Band ◽  
Star Evolution ◽  
Low Metallicity ◽  
Massive Star Evolution

AbstractThe lowest metallicity massive stars in the Local Universe with $Z\sim \left( {{Z}_{\odot }}/50-{{Z}_{\odot }}/30 \right)$ are the crucial objects to test the validity of assumptions in the modern models of very low-metallicity massive star evolution. These models, in turn, have major implications for our understanding of galaxy and massive star formation in the early epochs. DDO68-V1 in a void galaxy DDO68 is a unique extremely metal-poor massive star. Discovered by us in 2008 in the HII region Knot3 with $Z={{Z}_{\odot }}/35\,\left[ 12+\log \left( \text{O/H} \right)\sim 7.14 \right]$, DDO68-V1 was identified as an LBV star. We present here the LBV lightcurve in V band, combining own new data and the last archive and/or literature data on the light of Knot3 over the 30 years. We find that during the years 2008-2011 the LBV have experienced a very rare event of ‘giant eruption’ with V-band amplitude of 4.5 mag ($V\sim {{24.5}^{m}}-{{20}^{m}}$).

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