# c13_pocket¶

This test suite case shows a 2.0 $${\rm M}_\odot$$, $$Z = 0.01$$ thermally pulsing AGB star undergoing third dredge up. It is a re-implementation of the example shown in Section 7.2.1 of MESA I.

The test checks the development of a pocket of $$^{13}{\rm C}$$ during the thermal pulse cycle. This occurs due to the penetration of protons from the envelope into the He intershell as a result of mixing associated with convective overshoot and their capture on the $$^{12}{\rm C}$$ present in this region.

This test case has 4 parts, but by default, saved models are used to skip to part 3. Options shared between all parts are contained in inlist_common.

• Part 0 (inlist_pre_ms) creates the pre-main-sequence model.
• Part 1 (inlist_to_TACHeB) evolves from the pre-main-sequence to core helium depletion (TACHeB).
• Part 2 (inlist_to_3DUP) evolves from TACHeB until the third thermal pulse with third dredge-up has occurred.
• Part 3 (inlist_c13_pocket) evolves over a thermal pulse cycle and checks for the formation of the $$^{13}{\rm C}$$ pocket as well as surface enhancement of $$^{12}{\rm C}$$ due to third dredge up.

The most important options in parts 2 and 3 are contained in inlist_TP_AGB. This contains spatial/temporal resolution controls that ensure the thermal pulse cycle and the pocket are well resolved. This also adds the large exponential overshooting at the base of the convective envelope that mixes the protons into the intershell.

At the end of this test, MESA has succesfully evolved through a thermal pulse and the $$^{13}{\rm C}$$ pocket is apparent.

Note

When you run parts 0-2, the run_star_extras file attemps to automatically do the analysis reported in Table 11 of MESA I. This can be useful for detailed comparisons between versions. Uncomment the parts in rn and then grep in the output for [TestHub].

Last-Updated: 2020-03-12 (mesa r12778) by Josiah Schwab