[mesa-users] Extended helium envelopes

[Bill Paxton]

Hi Craig,

Send an inlist and a saved model after removing envelope but before it expands.
Then we can try it ourselves to see what might be going on.

Thanks,
Bill


On Oct 24, 2013, at 2:44 PM, Craig Wheeler wrote:

> Hi all,
> 
> We are trying to make ad hoc "Wolf-Rayet" models with MESA by stripping
> off the hydrogen envelope by hand from massive star models near the
> end of helium core burning. We are finding that the resulting "stripped
> envelope" models evolve normally for a while, but then are prone to
> having the remaining helium envelope expand to red-giant size,
> 100 R_sun or so. There is no question this can happen in some
> circumstances, for instance stars with a substantial helium abundance
> and a helium-burning shell atop a degenerate carbon/oxygen core, the
> supposed the structure of R Cor Bor stars. I have, however, no
> recollection of this expanding helium envelope phenomenon occurring
> in more massive, non-degenerate cores. The issue seems more acute
> for lower mass cores, a few to 10 solar masses, but may be related to
> opacity bumps, Eddington luminosity and radiation pressure. It also
> seems to be exacerbated by rotation.
> 
> Any perspective on this issue would be appreciated.
> 
> Thanks,
> 
> Craig
> 
> -- 
> J. Craig Wheeler
> Department of Astronomy
> 2515 Speedway, Stop C1400
> Austin, TX 78712-1205
> 512-471-6407
> http://www.as.utexas.edu/~wheel
> http://ebooks.cambridge.org/ebook.jsf?bid=CBO9780511536625
> http://www.smashwords.com/books/view/127749
> http://www.smashwords.com/books/view/178104
> http://www.amazon.com/The-Krone-Experiment-ebook/dp/B008Y6L3VW
> http://www.amazon.com/Krone-Ascending-ebook/dp/B00926QEGW
> http://www.amazon.com/The-Q-Man-1-ebook/dp/B00AFKJYKC
> 
> 
> ------------------------------------------------------------------------------
> October Webinars: Code for Performance
> Free Intel webinars can help you accelerate application performance.
> Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from 
> the latest Intel processors and coprocessors. See abstracts and register >
> http://pubads.g.doubleclick.net/gampad/clk?id=60135991&iu=/4140/ostg.clktrk
> _______________________________________________
> mesa-users mailing list
> mesa-users at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/mesa-users