[mesa-users] The Cepheid phase

[Earl Bellinger]

Excellent, thank you very much! Inlists would be very helpful.

Best regards,
Earl Bellinger
Stellar Ages & Galactic Evolution Group
Max-Planck-Institut für Sonnensystemforschung


On Fri, Jul 29, 2016 at 9:07 PM, Radek Smolec <smolec at camk.edu.pl> wrote:
> Hi Earl,
>
> The statement in Dziembowski's paper was about helium burning loop and
> relatively low mass Cepheids; Fig 14 in the third instrument paper shows the
> first crossing only.
>
> The loop is, and was tricky. In many published evolutionary tracks the
> presence or extent of the loop do not vary smoothly with mass or Z. It is
> difficult to get the loop for near solar metallicities and low masses,
> 3-5Ms. For lower metallicities and higher masses loops are quite easy to
> get. Adding some overshooting from the envelope convection zone helps.
>
> Note that we still have the Cepheid mass discrepancy problem, although it is
> significantly reduced, to 10-15%. We know that pulsation theory is right
> (Pietrzynski et al., 2010, Nature; other papers with determination of
> Cepheid's masses in eclipsing binaries), the evolution calculations need
> improvement. The recent papers point that rotation might be a solution.
>
> To summarize, Cepheids can be investigated with MESA, and there are still
> some problems to be solved (and lots of parameters to play with :-)
>
> I'm now on holidays; at the end of August I can send you the inlists I used
> for Cepheid calculations (but these are old; for MESA 4xxx, I think).
> Kind regards,
> Radek
>
>
> 2016-07-29 16:40 GMT+02:00 Earl Bellinger <bellinger at mps.mpg.de>:
>>
>> Hello everybody,
>>
>> In Dziembowski's 2012 paper [1] the claim is made that:
>>
>> > "BaSTI (Pietrinferni et al. 2006) models at M = 4 and 5 do not reach
>> > the instability strip [in the helium burning phase] but the maximum
>> > values of L in this evolutionary phase are in a good agreement with
>> > the relation given by Eq. (2). Similar conclusion was reached by
>> > Smolec (private communication), who used public domain code MESA
>> > (Paxton et al. 2011). Apparently, new evolutionary codes do not
>> > describe well the Cepheid phase."
>>
>> Can anyone corroborate/evaluate this claim for me please? That is: is
>> MESA suitable for investigating Cepheid stars? If not, why not?
>>
>> For example, can a theoretical Cepheid Period-Luminosity relation be
>> derived using MESA plus a pulsation code (ADIPLS/GYRE/etc)?
>>
>> Thanks for any insights.
>>
>> [1] http://acta.astrouw.edu.pl/Vol62/n4/pdf/pap_62_4_1.pdf
>>
>> Best regards,
>> Earl Bellinger
>> Stellar Ages & Galactic Evolution Group
>> Max-Planck-Institut für Sonnensystemforschung
>>
>>
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