[Mesa-users] Tip of the Red Giant Branch

[Francis Timmes]

hi mitchell,

give an example of a mass and metallicity that did not 
reach the desired peak i-band magnitude. also, how are 
the i-band absolute magnitudes being calculated?

> Do you know of a way to be sure that I’ve reached the RGB tip?


smaller timesteps are usually advantageous, as is a run_star_extras
to ensure smaller timesteps around the peak luminosity / helium ignition.


aldo serenelli et al's 2017 article 

https://ui.adsabs.harvard.edu/abs/2017A%26A...606A..33S/abstract

is all-around super awesome and much can be learned from it 
when attempting to build similar models using mesa.

fxt








> On Oct 7, 2021, at 7:40 PM, Mitchell Dennis <mtde226 at hawaii.edu> wrote:
> 
> Dear MESA Users,
>  
> I am running more follow up tests, and I was wondering if anyone has an inlist they would be willing to share for population II stars that yields an iBand magnitude of ~-4.0 at the tip of the red giant branch.
>  
> Best Regards,
> Mitchell T Dennis
> Graduate Student
> UH Manoa – Institute for Astronomy
>  
> From: Mitchell Dennis
> Sent: Friday, October 1, 2021 2:11 AM
> To: Adrian Ayala
> Cc: mesa-users at lists.mesastar.org
> Subject: RE: [Mesa-users] Tip of the Red Giant Branch
>  
> Dear Adrian,
>  
> I used a wide grid of different metallicities and masses. While some of the models did reach -4.1 many of them did not even though the research papers I read state metallicity and mass shouldn’t affect the iBand magnitude once at the TRGB. Do you know of a way to be sure that I’ve reached the RGB tip?
>  
> Best,
> Mitchell
>  
> From: Adrian Ayala
> Sent: Friday, October 1, 2021 12:16 AM
> To: mesa-users at lists.mesastar.org
> Subject: Re: [Mesa-users] Tip of the Red Giant Branch
>  
> Dear Mitchell,
>  
> you should interpolate between different tracks with different 
> metallicities and masses in order to reproduce the observed values. Did 
> you try this?
>  
> Best
>  
> On 01/10/2021 12:13, Adrian Ayala wrote:
> > Dear Mitchell,
> > 
> > 
> > On 01/10/2021 11:04, Francis Timmes via Mesa-users wrote:
> >> hi mitchell,
> >> 
> >>> Is this typical for MESA at the TRGB ...
> >> 
> >> mesa is a tool, not a model. i note that the inlist for your model
> >> relies entirely on the default mass and temporal resolution criteria.
> >> these default settings may be good enough for a nightly test suite case,
> >> but they are probably not good enough for publication quality science.
> >> best practices includes varying the default settings:
> >> 
> >> https://docs.mesastar.org/en/latest/using_mesa/best_practices.html
> >> 
> >> others can chime in on color filters ...
> >> 
> >> fxt
> >> 
> >> 
> >> 
> >> 
> >> 
> >> 
> >> 
> >>> On Sep 30, 2021, at 5:32 PM, Mitchell Dennis <mtde226 at hawaii.edu> 
> >>> wrote:
> >>> 
> >>> Dear MESA Mailing List,
> >>>   I am doing work on stars at the tip of the red giant branch, and 
> >>> although several research papers cite an iBand Magnitude of -4.1 
> >>> with a theoretical iBand Magnitude of ~-4, many of my models only 
> >>> reach an iBand Magnitude of -3.8. Is this typical for MESA at the 
> >>> TRGB, or am I missing a correction that I need to apply to the MESA 
> >>> absolute magnitude iBand output?
> >>>   My current stopping condition is the power_he_upper_burn_limit 
> >>> which is set to 1.0d6. Typical mass, metallicity and helium 
> >>> abundance are 1.0, 0.0006 and 0.25.
> >>>   I’ve attached a copy of my inlist which is based on the test_suite 
> >>> he_core_flash, and my run_star_extras file is unmodified.
> >>>   Do you have any suggestions for determining whether a model will 
> >>> flash or not?
> >>>   Thanks for the help
> >>>   Best Regards,
> >>> Mitchell T Dennis
> >>> Graduate Student
> >>> UH Manoa – Institute for Astronomy