[Mesa-users] Question about RSP and equilibrium quantities

[Jeremy Sakstein]

I think it does alternate. Here is a zoom in over 20 cycles:

[image: image.png]

Here is a plot with 3 alternating cycles:

[image: image.png]

The three colours correspond to the different cycles so with the exception
of the number/position of data points it appears the plots are identical.
Here's the radius, which also looks identical:

[image: image.png]

I'm not using the time-steps at all. I made these points by picking out the
data points where the pulsation cycle (rsp_num_periods) is fixed to some
value.


On Tue, Jan 21, 2020 at 9:47 AM Radek Smolec <smolec at camk.edu.pl> wrote:

> So does it alterante between two values?
> Can you attach a plot of a few consecutive pulsation cycles, maybe with
> zoom at radii maxima or minima?
> If you get alteranating values of average radius the consecutive pulsation
> cycles must differ.
>
> One other idea, do you interpolate for start of the pulsation cycle? If
> you use the time steps as used by rsp, without interpolation, then some
> scatter in the averaged radius is possible (but likely not alternations).
> Radek
>
>
> wt., 21 sty 2020 o 20:39 Jeremy Sakstein <sakstein at hawaii.edu> napisał(a):
>
>> Hi Both,
>>
>> I don't think it's periodu doubling because I just see a single harmonic
>> when I plot the light curves.
>>
>> Sorry to be unclear. I am plotting the average stellar (surface) radius
>> for each pulsation cycle.
>>
>> On Tue, Jan 21, 2020 at 9:37 AM Radek Smolec via Mesa-users <
>> mesa-users at lists.mesastar.org> wrote:
>>
>>> Hi Jeremy,
>>>
>>> It is difficult to guess what is happening without more detailed
>>> information. The effect you describe may be physical: for example
>>> low-amplitude period doubling phenomenon may be present in your model and
>>> then averages for even and odd pulsation cycles will differ.
>>> With such large difference you should be able to figure it out simply
>>> looking at the light or radius variation curve.
>>>
>>> For the general point; what you consider as "true equilibriu model"? RSP
>>> starts from equilibrium model, but it doesn't mean that the linear
>>> properties of the model, such as pulsation period, will not change when
>>> model pulsates at full amplitude.
>>> It is best to develop own procedures for computing such quantities as
>>> mean magnitude, radius, etc.
>>> Cheers,
>>> Radek
>>>
>>>
>>> wt., 21 sty 2020 o 20:20 Jeremy Sakstein <sakstein at sas.upenn.edu>
>>> napisał(a):
>>>
>>>> Hi Everyone,
>>>>
>>>> I have a quick question about finding the equilibrium values of the
>>>> stellar parameters when using RSP Cepheid.
>>>>
>>>> At the moment, I am taking a single pulsation cycle and averaging over
>>>> the radius throughout the cycle but this seems to give me two (very closely
>>>> separated values).
>>>>
>>>> Below I am plotting radius vs pulsation number. As you can see, I end
>>>> up with two very closely separated values for the average. Is this because
>>>> the model is changing ever so slightly between pulsations? If so, why does
>>>> it converge to two values and not a small scatter about the mean?
>>>>
>>>> [image: image.png]
>>>>
>>>> On a more general point, is it possible to extract the true equilibrium
>>>> model from the output rather than taking an average?
>>>>
>>>> Cheers,
>>>>
>>>> Jeremy
>>>> _______________________________________________
>>>> mesa-users at lists.mesastar.org
>>>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>>>
>>>> _______________________________________________
>>> mesa-users at lists.mesastar.org
>>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>>
>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20200121/df970a0e/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 7667 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20200121/df970a0e/attachment-0004.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 19402 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20200121/df970a0e/attachment-0005.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 31932 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20200121/df970a0e/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 11526 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20200121/df970a0e/attachment-0007.png>