[mesa-users] Sharing some modeling questions with YOU ...

Ehsan Moravveji moravveji at iasbs.ac.ir
Fri Jul 8 16:50:26 EDT 2011

Dear MESA users,
Hi. I'm Ehsan, a PhD student from Iran. It is more
than a year I'm trying to find a suitable model from MESA that fits
simultaneously all the (exhaustive list of) observed properties of the
blue supergiant Rigel (beta Ori). This model would serve as an input to a
non-adiabatic pulsation code.
The reason I write this message to MESA
community is that I'm sure there are many experts that read this. I'm just
asking for your ideas regarding some points:

1- As usual, the
"standard" MESA models that I calculate cannot explain properly
the pulsational modes of Rigel. Hence, I have to try other possibilities.

2- The first point is that Rigel has surface He abundance
Ys=0.32+/-0.04, and vsini = 25+/-3 at solar metalicity. The only way I
found to enhance surface He is just by rotation, but when my model of
M=19Msun terminates at Teff = 12100+/-150 K, the surface velocity is
around 80 km/s, much higher than the observed one. This Ys has substanial
effect in driving radial modes, that I'm seeking to find.
If you have
any idea to mix He to the surface (even Ys=0.36) and keeping surface
rotation low, I'd be really appreciating.

3- Secondly, I also
like to increase the effect of kappa mechanism at the Iron bump of
opacity, but would like to know some "rational" ways to do so,
so that the refree of the paper would not argue !
Any idea on how to
enhance metals around this zone (logT=5.2) and increase the bump height is
the most welcome.

With kind regards.

Ph.D student of Astrophysics.
Department of Physics,
Institute for Advanced Studies in Basic Sciences (IASBS), GavaZang Road,

Zanjan 45137-66731, Iran.

Office: (+98)241-415 2118
Fax:    (+98)241-415 2104

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