# [Mesa-users] chemical abundances

Meisel, Zach meisel at ohio.edu
Fri May 1 06:11:03 EDT 2020

Hi Yunlang,

I’m not (and am likely not going to be) very familiar with the details of your model, so hopefully someone with more nova experience can comment.

As you note, the mass fraction should sum to one  (or at least should come pretty close, within some numerical tolerance). Nucleosynthesis won’t impact the sum, because that just converts some fraction of the mass from one isotope (or more) to another (or others).

Since you’re using total_mass, presumably you’re calculating the mass fractions yourself and summing. I think you need to check that you’re doing your mass fraction calculations properly.  I’m also not sure you really want the total_mass, since this will include your envelope. Unless I misunderstand and by “nova cycle” you’re not talking about a nova explosion on an accreting white dwarf.  If you are talking about a nova explosion, then the mass fractions of your initially created envelope aren’t particularly relevant for nova nucleosynthesis.

-Zach

----
Zach Meisel
Assistant Professor of Physics & Astronomy
Director, Edwards Accelerator Laboratory
Ohio University
Email: meisel at ohio.edu
Web: http://inpp.ohio.edu/~meisel

From: 郭云浪<mailto:yunlang at ynao.ac.cn>
Sent: Thursday, April 30, 2020 11:01 PM
To: Meisel, Zach<mailto:meisel at ohio.edu>
Subject: Re: RE: [Mesa-users] chemical abundances

Hi Zach,

Thank you!

I have try the case 2 you proposed,  using the total_mass_X option to obtain the chemical abundances of eject material.

The specific method is as follows：

the chemical abundances of eject material = total_mass_X(wind start) - total_mass_X(wind end) ,

as we know, a star wind will be generated when nova erupts start,

and I checked the result and found that in some cases, sum of all chemical abundances exceeded 1.

I think this is because some isotope (such as He, C, O, Ne) is produced during the occurrence of the star wind due to the nuclear reaction,

and I can't tell whether part of these elements were ejected or formed by H/He burning (or other nuclear reaction),

I think the case 1 will face the same problem .

lang

-----原始邮件-----

Hi Yunlang,

There are several options, depending on what you want to do.

You can report the mass fractions for all isotopes included in the reaction network for each radial zone at each timestep that a profile file is recorded by adding “add_abundances” to your profile_columns.list file.  There are several other possibilities for profile files. Probably the best way to see what they are is to look at all of the commented-out good stuff in the default profile_columns.list file, located at /mesa-r###/star/defaults/profile_columns.list,  where ### is the version of MESA you are running.

You can also report abundance information for each timestep in your history.data file, which is done using the history_columns.list file. Again, it would be good to peruse the default file, located in the same directory mentioned above.  You may be interested in the line “add_total_mass” to report the mass total for an isotope in the entire star or “add_average_abundances” for the average abundance of an isotope for the star.

My assumption is that you’re looking for mass fractions in a specific radial region over time, or for some snapshot in time. I think you want to go the profile_columns.list route in that case. Or perhaps you could define something custom in run_star_extras.f.  As usual, the MESA mailing list archives might help if someone has tried/succeeded-at something similar before: https://lists.mesastar.org/pipermail/mesa-users/<https://nam03.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.mesastar.org%2Fpipermail%2Fmesa-users%2F&data=02%7C01%7Cmeisel%40ohio.edu%7C0052fa32956542acf17a08d7ed7bed31%7Cf3308007477c4a70888934611817c55a%7C0%7C0%7C637238988834132963&sdata=NH2V%2FPdfKiUZ30TVw1%2FTWBrY9ZRjZz2yjNP1ZunBs3A%3D&reserved=0>

-Zach

----
Zach Meisel
Assistant Professor of Physics & Astronomy
Director, Edwards Accelerator Laboratory
Ohio University
Email: meisel at ohio.edu
Web: http://inpp.ohio.edu/~meisel

From: 郭云浪<mailto:yunlang at ynao.ac.cn>
Sent: Thursday, April 30, 2020 6:16 AM
To: mesa-users at lists.mesastar.org<mailto:mesa-users at lists.mesastar.org>
Subject: [Mesa-users] chemical abundances

Hi all,

How can i get the chemical abundances (mass fraction) of isotopes during a nova cycle?

Thanks so much, really appreciate any guidance on this.

Yunlang

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