Re: [mesa-users] Rapidly Rotating A-Stars

Hi,
Just to have in mind orders of magnitude for a 2.5Msun star (early 
A-type, solar Z), the 1D model gives a good estimate of the polar radius 
(2% err), it underestimates polar temperature (500K over 11000K) and 
overestimates luminosity (10%), when the rotation of the star is 95% 
critical; if rotation is less errors are less.

best,

Michel

*****************************************************************************
Michel Rieutord
Institut de Recherche en Astrophysique et Planétologie
Observatoire Midi-Pyrénées           email : [email protected]
14 avenue Edouard Belin                 Tel +33 -(0)5 61 33 29 49
31400 Toulouse, France                  Fax +33 -(0)5 61 33 28 40
*****************************************************************************

Le 06/10/2013 22:06, Jeremy Jones a écrit :
> Thanks for all of your responses. I'll definitely take a look at the 
> ESTER code.
>
> In the meanwhile, I was thinking I would compare the polar radius, 
> equatorial velocity, and luminosity calculated by my model fitting to 
> the interferometric data to those same outputs from mesa (now that I 
> know the polar radius parameter exists... I must have missed it when I 
> was looking through all the parameters) in order to get the age/mass 
> of the stars I observed. Since I've got a handful of stars that should 
> be coeval (UMa moving group, some slow rotators (v_eq <100 km/s) and 
> some rapid rotators), it'll be interesting to see the results I get 
> out of mesa even if it is a 1-D code. Ideally, I'll be using as many 
> evolution models as I can get my hands on for my thesis, but there are 
> only so many hours in the day...
>
> ~Jeremy
>
> -- 
> Jeremy Jones
> Graduate Student Assistant
> Georgia State University
> Department of Physics & Astronomy
> [email protected] <mailto:[email protected]>
>
>
> On Sun, Oct 6, 2013 at 7:16 AM, Michel Rieutord <[email protected] 
> <mailto:[email protected]>> wrote:
>
>     Le 05/10/2013 14:18, Michel Rieutord a écrit :
>>     Hi Jeremy,
>>
>>     I think the best answer to your question is to be found with the
>>     ESTER
>>     code that you can freely download at
>>     http://code.google.com/p/ester-project/
>>
>>     This is a code that computes the 2D structure, including differential
>>     rotation and meridional circulation, of rotating early-type stars at
>>     any rotation rate (below critical of course). With this code
>>     you'll be
>>     able to compare your data with those of the model including the
>>     temperature dependence with latitude; by adjusting the hyrdogen
>>     content
>>     of the core you may get an idea of the evolution status of your
>>     star on
>>     the main sequence. This won't give you an age in years but this can
>>     obtained with a 1D code afterwards. We are working out the time
>>     evolution but this is not yet ready; this a tough problem all the
>>     more
>>     that we need to also evolve the dynamics...
>>
>>     You may find examples of the results in
>>     Espinosa Lara & Rieutord 2013, A&A, 552, A35
>>     Rieutord & Espinosa Lara 2013, LNP 865, 49, Arxive 1208.4929
>>     or  2013arXiv:1310.0908 <tel:1310.0908>   or   arXiv:1310.1017
>>     <tel:1310.1017>
>>
>>     Don't hesitate if you have questions.
>>
>>     Best wishes,
>>
>>     Michel Rieutord
>>
>     PS third attempt; hope this is the good one.
>
>>     **************************************************************************
>>     Michel Rieutord
>>     Institut de Recherche en Astrophysique et Planétologie
>>     Observatoire Midi-Pyrénées      email :[email protected]  <mailto:[email protected]>
>>     14 avenue Edouard Belin                Tel+33 -(0)5 61 33 29 49  <tel:%2B33%20-%280%295%2061%2033%2029%2049>
>>     31400 Toulouse, France                 Fax+33 -(0)5 61 33 28 40  <tel:%2B33%20-%280%295%2061%2033%2028%2040>
>>     **************************************************************************
>>     Le 04/10/2013 22:25, Jeremy Jones a écrit :
>>>     Hey mesa users,
>>>
>>>     I'm working on a project concerning interferometry of A-stars.
>>>     Many of my targets are rapid rotators, and I'm looking into
>>>     using mesa to determine their ages. I've played around with mesa
>>>     a bit (I've included one of my inlists below). I have a question
>>>     about how to compare my observables with the mesa outputs, in
>>>     particular radius and temperature.
>>>
>>>     From the modeling I do of the inerferometric data, I get the
>>>     full radius profile of the star (i.e. radius as a function of
>>>     latitude). Likewise, I get the full temperature profile of the star.
>>>
>>>     My question is for a rapid rotator, which radius/temperature
>>>     should I compare with the mesa outputs to get the age of the
>>>     star? Polar radius/temperature, equatorial radius/temperature,
>>>     something more involved?
>>>
>>>     Thanks for any insight!
>>>
>>>     ~Jeremy
>>>
>>>     The aforementioned inlist:
>>>     ================
>>>     &star_job
>>>
>>>           mesa_dir = '../..'
>>>
>>>           set_initial_age = .true.
>>>           initial_age = 0 ! in years
>>>
>>>           set_initial_model_number = .true.
>>>           initial_model_number = 0
>>>
>>>           create_pre_main_sequence_model = .true.
>>>           new_omega_div_omega_crit = 0.5
>>>     near_zams_relax_omega_div_omega_crit = .true.
>>>
>>>           pgstar_flag = .true.
>>>
>>>
>>>     / ! end of star_job namelist
>>>
>>>
>>>     &controls
>>>
>>>           min_timestep_limit = 1d-12 ! (seconds)
>>>
>>>           ! check for retries and backups as part of test_suite
>>>           ! you can delete this for use outside of test_suite
>>>              max_number_backups = 400
>>>              max_number_retries = 900
>>>              max_model_number = 1500
>>>
>>>              !max_allowed_nz = 20000 ! maximum number of grid points
>>>     allowed
>>>
>>>              initial_mass = 2
>>>              initial_z = 0.016
>>>
>>>              photostep = 10
>>>              profile_interval = 10
>>>              history_interval = 1
>>>              terminal_interval = 2
>>>              write_header_frequency = 10
>>>
>>>     / ! end of controls namelist
>>>
>>>
>>>     &pgstar
>>>
>>>     History_Track1_win_flag = .true.
>>>     History_Track1_yname = 'log_R'
>>>     History_Track1_yaxis_label = 'log(R/R_sun)'
>>>     History_Track1_xname = 'log_Teff'
>>>     History_Track1_xaxis_label = 'log(T/K)'
>>>     History_Track1_title = 'Radius vs. Effective Temperature'
>>>
>>>     History_Track2_win_flag = .true.
>>>     History_Track2_yname = 'surf_avg_v_rot'
>>>     History_Track2_yaxis_label = 'Equatorial Velocity (km/s)'
>>>     History_Track2_xname = 'star_age'
>>>     History_Track2_xaxis_label = 'Age (yr)'
>>>     History_Track2_title = 'Surface Velocity vs. Age'
>>>
>>>     / ! end of pgstar namelist
>>>     ================
>>>
>>>     -- 
>>>     Jeremy Jones
>>>     Graduate Student Assistant
>>>     Georgia State University
>>>     Department of Physics & Astronomy
>>>     [email protected] <mailto:[email protected]>
>>>
>>>
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>>
>
>

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