[Mesa-users] Astero: delta_nu with a single radial frequency

[Kuldeep Verma]

Hi Jacqueline,

As Earl replied, delta_nu is calculated using the asymptotic expression
(not using the scaling relation though).

Here is what grep has to say about the calculation of delta_nu:
 star/public/star_data.inc:      real(dp) :: delta_nu ! in micro Hz.  =
10^6/(2*photosphere_acoustic_r)

Best wishes,
Kuldeep

On Tue, Oct 8, 2019 at 1:45 AM Earl Bellinger via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi Jacqueline,
>
> I haven't checked, and this is only a guess, but is it possible that it's
> using the asymptotic value? That is:
>     Delta_nu/Delta_nu_solar = sqrt(M/R**3)
> with M and R being in solar units and Delta_nu_solar ~= 135.1 muHz.
>
> Best regards,
> Earl
>
>
> On Tue, Oct 8, 2019 at 6:17 AM Jacqueline Goldstein via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
>
>> Hi MESA users,
>>
>> How does the astero module determine/use delta_nu when only provided a
>> single radial frequency?
>>
>> In my inlist, I am only using first values and only using aster-seismic
>> constraints.
>> The radial frequency is:
>>
>>   chi2_seismo_fraction = 1d0          # only seismic constraints
>>   normalize_chi2_spectro = .false.  #need when chi2_seismo_fraction = 1.
>>
>>
>>   nl0 = 1 ! number of observed l=0 modes
>>
>>   l0_obs(1) =  66.704 !                     # microhertz
>>   l0_obs_sigma(1) = 0.001
>>
>>   l0_n_obs(1) = 1                            # radial order
>>
>>
>> I have three additional dipole frequencies.
>>
>> I am leaving the default value of
>>
>> delta_nu = -1
>> delta_nu_sigma = -1
>>
>>
>> The module runs, but how does the astero module treat delta_nu with this
>> single radial frequency?
>>
>> In astero_support.f I see:
>>
>> if (delta_nu <= 0 .and. nl0 > 1 .and. l0_n_obs(1) > 0) then…
>>
>> But I can’t determine what happens when delta_nu <=0 I only have a single
>> radial frequency.
>>
>> Sincerely,
>>
>> Jacqueline Goldstein
>> PhD Graduate Student | Astronomy
>> University of Wisconsin - Madison
>> http://www.astro.wisc.edu/~jgoldstein
>>
>>
>>
>>
>>
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