[Mesa-users] Question about nuclear reaction rates

[王浩]

Dear Francis Timmes,




Thank you for your criticism. I will pay attention to this problem in the future. Moreover, I am grateful for your patience in answering my questions. If I have any further inquiries, I hope to stay in touch with you.




Best wishes,

Wang Hao

-----原始邮件-----
发件人:"Francis Timmes" <fxt44 at mac.com>
发送时间:2023-07-19 00:13:08 (星期三)
收件人: "王浩" <wangfeihao at stu.xju.edu.cn>
抄送: "Frank Timmes" <fxt44 at mac.com>, mesa-users <mesa-users at lists.mesastar.org>
主题: Re: [Mesa-users] Question about nuclear reaction rates


please keep all replies on mesa-users.




just follow the units:


energy/time = energy/reaction * reaction/time


4e33 erg/sec ~ 4.2e-5 erg/reaction * reaction/sec


so, 


reaction/sec ~ 4e33/4.2e-5 ~ 1e38


fxt








On Jul 17, 2023, at 11:28 PM, 王浩 <wangfeihao at stu.xju.edu.cn> wrote:


Dear Francis Timmes,

Thank you very much for your explanation. But I don't know what to make of 4e33/4e-5 on the last line. Why divide the sun's luminosity by 4e-5.

Best wishes,
Wang Hao


-----原始邮件-----
发件人: "Francis Timmes" <fxt44 at mac.com>
发送时间: 2023-07-17 22:55:27 (星期一)
收件人: "王浩" <wangfeihao at stu.xju.edu.cn>
抄送: "Frank Timmes" <fxt44 at mac.com>, mesa-users <mesa-users at lists.mesastar.org>
主题: Re: [Mesa-users] Question about nuclear reaction rates

to polish this off from my side,

pp I energetics:

p + p -> d + e^+ + nu

the positron annihilates, so

p + p -> d + nu + 1.442 MeV

d + p -> he3 + gamma + 5.493 MeV

he3 + he3 -> he4 + 2p + 12.732 MeV

so the net is 4p -> he4 + 26.1 MeV, accounting for the ~0.6 MeV lost to neutrinos.

26.1 MeV ~ 4.2e-5 erg, so the number of pp I reactions per second to sustain Lsun is ~4e33/4e-5 ~ 1e38 reactions/sec, which is commensurate with fig 25 of mesa VI.

fxt



On Jul 17, 2023, at 5:49 AM, 王浩 <wangfeihao at stu.xju.edu.cn> wrote:

Dear Francis Timmes,

Thank you sincerely for recommending those books to me. They have proven to be incredibly helpful.

Best wishes,
Wang Hao





-----原始邮件-----
发件人: "Francis Timmes" <fxt44 at mac.com>
发送时间: 2023-07-16 23:31:20 (星期日)
收件人: "王浩" <wangfeihao at stu.xju.edu.cn>
抄送: "Frank Timmes" <fxt44 at mac.com>, mesa-users <mesa-users at lists.mesastar.org>
主题: Re: [Mesa-users] Question about nuclear reaction rates

Meanwhile, I would like to understand the definition of the nuclear reaction rates within a star and its units.

amongst several textbooks, "nuclear physics of stars" second edition by christiam iliadis or "essentials of nucleosynthesis and theoretical nuclear astrophysics" by thomas rauscher.

fxt




On Jul 16, 2023, at 3:02 AM, Earl Bellinger via Mesa-users <mesa-users at lists.mesastar.org> wrote:

Dear Wang Hao,

Many thanks for your email. The inlists and code to generate Figure 25 are included in the following MESA Zenodo repository:
  https://zenodo.org/record/6968760
I have just run it with mesa-r22.05.1 and found that I get similar results as what was presented in the paper.

If you can point to some discrepancies then I would be happy to take a further look.

Best wishes,
Earl

Earl Patrick Bellinger Postdoctoral Research Fellow
Max Planck Institute for Astrophysicshttps://earlbellinger.com

On Sun, Jul 16, 2023 at 5:40 AM 王浩 <wangfeihao at stu.xju.edu.cn> wrote:
Hi, everyone,

I’m very interested in using mesa-r22.05.1 to obtain nuclear reaction rates. However, I have encountered a particular issue. When I output the nuclear reaction rate of a 1M⊙ model using mesa-r22.05.1, the magnitude of the rates I obtain is significantly smaller than what is depicted in Figure 25 of paper titled “Modules for Experiments in Stellar Astrophysics (MESA): Time-Dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure,” which was published in the APJS. I wonder why that is. Meanwhile, I would like to understand the definition of the nuclear reaction rates within a star and its units.

Best regards,
Wang Hao
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