[Mesa-users] [mesa-users] Rapidly Rotating A-Stars
Michel Rieutord
Michel.Rieutord at irap.omp.eu
Mon Oct 7 04:24:52 PDT 2013
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 : Michel.Rieutord at irap.omp.eu
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
> jones at chara.gsu.edu <mailto:jones at chara.gsu.edu>
>
>
> On Sun, Oct 6, 2013 at 7:16 AM, Michel Rieutord <mrieutord at irap.omp.eu
> <mailto:mrieutord at irap.omp.eu>> 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 :Michel.Rieutord at irap.omp.eu <mailto:Michel.Rieutord at irap.omp.eu>
>> 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
>>> jones at chara.gsu.edu <mailto:jones at chara.gsu.edu>
>>>
>>>
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>>
>
>
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