[mesa-users] Kjeldsen correction in astero module

[Santiago Andres Triana]

Hi Dennis, mesa users,

I'm a bit confused now... (I am doing some tests with no correction
for the moment) the value reported by delta_nu_model is the 'cheap'
one (i.e. obtained with an integral involving the Brunt Vaisala
frequency) when we are still 'cold'. And then, when we are 'warm'
delta_nu_model is obtained from the radial modes reported by gyre? It
seems not to be the case... I don't see the 'drop' anymore (but it
shows when I do corrections)

I did a single run with no correction and saved the models. Then I ran
gyre manually on these models
and calculated delta_nu_model independently. it doesn't match what the
delta_nu_model says from the history file.

I have the feeling I am going to learn something obvious :) but still
don't know exactly what that is. Thanks again!

Cheers,

Santiago

On Tue, Feb 17, 2015 at 12:00 AM, Dennis Stello
<stello at physics.usyd.edu.au> wrote:
> Hi Santiago,
>
> I think what you are experiencing is the known offset between the asymptotic
> delta_nu and that from the 'average' spacing between overtone modes in the
> observed frequency range.  We start using the asymptotic delta_nu as a guide
> for how close we are to a good solution because it is cheap.  When you get
> close, we start with the radial modes.
>
> As you say, increasing the assumed uncertainty in delta_nu is a way to make
> sure we will find the solution.
>
> However, to make is easier to tune the delta_nu value, the next release of
> MESA will plot the radial modes in the echelle etc as soon as they are
> calculated, giving you a better feel for if you need to decrease or increase
> delta_nu (thanks to Bill).  So after a few test runs, you will have a feel
> for what delta_nu and delta_nu_sigma are most efficient and still robust.
>
> Cheers
> Dennis/
>
>
>
> On Mon, 16 Feb 2015, Santiago Andres Triana wrote:
>
>> Dear Dennis, Kuldeep & MESA users,
>>
>> Thanks for the hints! I did look into the simplex_results.data and the
>> 'a_div_r' column was all zeros. I think the reason is that I was
>> providing a 'delta_nu' in the inlist slightly above (about 10%) of the
>> observed delta_nu mean (I was thinking that it was better to use a
>> value as close as possible to the asymptotic delta_nu there). This
>> leads to a correction_b <1 and therefore no correction overall.
>>
>> Additionally, I had not provided the orders in l0_n_obs(:). It was
>> bound to fail indeed.
>>
>> Now I'm a bit further after providing the radial orders and providing
>> the correct delta_nu to match the observed mean (or letting the module
>> calculate it by setting delta_nu=-1). The only thing is that there is
>> a drop in delta_nu_model as soon as the module starts using the
>> l0_freqs (instead of using the Brunt-Vaisala frequency) to calculate
>> it (see the figure). In my earlier experiments this drop was
>> preventing me from finding good chi2_radial. Now I can tweak
>> delta_nu_sigma to make the module calculate delta_nu_model from
>> l0_freqs sooner.
>>
>> Hope this make any sense, please let me know otherwise. Again, many
>> thanks for further ideas!
>>
>> Cheers,
>>
>> Santiago
>>
>> On Mon, Feb 16, 2015 at 10:21 PM, Dennis Stello
>> <stello at physics.usyd.edu.au> wrote:
>>>
>>> Hi Santiago,
>>>
>>> It sounds to me that what you are looking for is in the simplex results
>>> file....did you you look there?
>>>
>>> Cheers
>>> Dennis/
>>>
>>> -------
>>> DENNIS STELLO | Senior Lecturer
>>> School of Physics A28 | Faculty of Science
>>>
>>> THE UNIVERSITY OF SYDNEY
>>> Rm225, K90 | The University of Sydney | NSW | 2006
>>> T +61 2 9036 5108  | F +61 2 9351 7726
>>> E stello at physics.usyd.edu.au  | W http://www.physics.usyd.edu.au/~stello/
>>>
>>>
>>>
>>> On Sat, 14 Feb 2015, Santiago Andres Triana wrote:
>>>
>>>> Hi MESA users,
>>>>
>>>> Playing around with the astero module and simplex, I noticed that the
>>>> frequencies, as reported in the sample_#.data files, are not
>>>> corrected. They seem to be the raw, uncorrected  frequencies from gyre
>>>> although I have specified the 'kjeldsen' method in
>>>> inlist_astero_search_controls.
>>>>
>>>> The inlist is attached. The relevant snippet is this:
>>>>
>>>>    ! surface corrections
>>>>      correction_scheme = 'kjeldsen' ! options are
>>>>         ! 'kjeldsen'   Correction of Kjeldsen et al. (2008)
>>>>         ! 'cubic'      Cubic correction of Ball & Gizon (2014, eqn 3)
>>>>         ! 'combined'   Combined correction of Ball & Gizon (2014, eq 4)
>>>>         ! ''           no corrections
>>>>      correction_factor = 1
>>>>         ! use this fraction of the correction; set to 0 to skip doing
>>>> corrections.
>>>>      l0_n_obs(:) = -1 ! the observed radial orders (ignored if < 0)
>>>>         ! the observed radial orders are used in calculating surface
>>>> corrections
>>>>         ! if <= 0, use default calculation for radial orders
>>>>      correction_b = 4.25d0
>>>>
>>>>      save_next_best_at_higher_frequency = .true.
>>>>      save_next_best_at_lower_frequency = .true.
>>>>
>>>>
>>>> I'm convinced that I'm doing something silly somewhere but cannot
>>>> figure out where... any hints or comments are very much appreciated.
>>>> Many thanks in advance!
>>>>
>>>> Cheers,
>>>>
>>>> Santiago
>>>>
>>>
>>
>