[Mesa-users] Initiating Mass Loss in Massive Star Model

[Jared Goldberg]

Broadly speaking, yes .

To turn on the Dutch prescription, first set the various *wind_scheme
= 'dutch'.
Note also that the "Dutch" prescription for mass loss is actually few
different prescriptions activated at different points in the HR diagram and
surface hydrogen fraction. The documentation
<https://docs.mesastar.org/en/latest/reference/controls.html#dutch-scaling-factor>
explains:

The “Dutch” wind scheme for massive stars combines results from several
> papers, all with authors mostly from the Netherlands.

The particular combination we use is based on Glebbeek, E., et al, A&A 497,
> 255-264 (2009) [more Dutch authors!]

For Teff > 1e4 and surface H > 0.4 by mass, use Vink et al 2001 Vink, J.S.,
> de Koter, A., & Lamers, H.J.G.L.M., 2001, A&A, 369, 574.

For Teff > 1e4 and surface H < 0.4 by mass, use Nugis & Lamers 2000 Nugis,
> T.,& Lamers, H.J.G.L.M., 2000, A&A, 360, 227 Some folks use 0.8 for
> non-rotating mdoels (Maeder & Meynet, 2001).


The dutch_scaling_factor, as you correctly state, scales the entire mass
loss rate by the number specified (when > 0). So just to say it out loud,
if dutch_scaling_factor = 0.5, then at every timestep, the mass loss at
each timestep is whatever the baseline prescription determines times 0.5.
If dutch_scaling_factor = 2, then the mass loss is enhanced by a factor of
2. And so on.

As Amadeo notes, these aren't the only prescriptions out there and they're
potentially out of date in various ways. See e.g. Renzo+17
<https://ui.adsabs.harvard.edu/abs/2017A%26A...603A.118R/abstract> which
explores the effects of choosing different mass loss prescriptions (some of
which go into the Dutch prescription). More recent work by Beasor+2020
<https://ui.adsabs.harvard.edu/abs/2023MNRAS.524.2460B/abstract> and
Decin+2024
<https://ui.adsabs.harvard.edu/abs/2024A%26A...681A..17D/abstract> also
argue that mass-loss rates in the cool luminous regime are likely
over-estimated (but for different reasons than the clumping which Amadeo
mentioned), with different luminosity scalings (see Fig. 2 of Decin+2024).
So, depending on your science case and what phases of stellar evolution
you're considering, you may decide upon different scaling factors or
different prescriptions.

Cheers,
~Jared


On Mon, Mar 25, 2024 at 4:04 AM Amedeo Romagnolo via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi Shaquann,
>
> You can interpret the scaling factors in different ways.
>
> The Dutch winds are the *canon* prescription for winds in MESA, but as any
> other wind prescription they are far from being *proper*.
>
> These scaling factors are implemented as a form of quick calibration for
> what you need to simulate. For instance, at Solar metallicity we know that
> Dutch winds do lose too much mass during main sequence, if compared to
> current observations and theoretical understanding of clumped winds, so you
> might want to set...say...a Vink scaling factor of 0.3 or 0.5 (clumped
> winds were found to be 2-3 times weaker, Mdot-wise, than homogeneous ones)
>
> Also, being calibration controls, the scaling factors are not necessarily
> just a reduction. Depending on what you are looking for (e.g. LBV mass loss
> rates) you might need to increase them for specific periods of the
> evolution of the star.
>
> The highlight, all things considered, is that Dutch(-like) winds
> prescriptions are the standard in many 1D stellar models (not only limited
> to MESA), but also a bit outdated, so if you want to use them, these
> scaling factors are an easy way to calibrate your mass loss rates without
> writing a new prescription on your own :)
>
> Hope this helps.
>
> Cheers and have a nice beginning of the week,
>
> Amedeo Romagnolo
>
> On Mon, 25 Mar 2024, 06:05 Shaquann Seadrow via Mesa-users, <
> mesa-users at lists.mesastar.org> wrote:
>
>> Dear Mesa users,
>>
>> I am currently making modifications to a 20 solar mass model. I am
>> exploring how to initiate winds via the 'Dutch' routine. I noticed that
>> there are these "_scaling_factor" controls. I wanted know if this is more
>> of an artificial 'tweak' to the mass loss (ie 0.0 = no loss, 1.0 =
>>  "normal" mass loss under the proper relation, 0> scale_factor <1 is a
>> reduction, etc). I look forward to your reply.
>>
>> Best,
>> Shaquann
>>
>> --
>> Shaquann S. Seadrow
>> PhD. Candidate
>> Dept. of Physics & Astronomy
>> University of Delaware
>>
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