In-Class Assignment 14

In-Class Assignment 14#

The TP-AGB Phase#

Learning Objectives#

  • explore the 3DU event in intermediate mass stars

  • gain a qualitative understanding of the He-shell flash region and interpulse properties

  • explore implications of c13 pocket in a low mass AGB star

import numpy as np
import matplotlib.pyplot as plt
import pandas as pd

Download the following model file locally. These data were produced using the c13_pocket test suite.

  • \(3 M_{\odot}\): 3m_to_3DU_history.data; - the model starts from core He-depletion.

  • \(3 M_{\odot}\): 3m_c13_pocket_history.data; - this data covers one full thermal pulse and captures the presence of a c13 pocket.

  • \(3 M_{\odot}\): LOGS.zip; - this contains a LOG folder and one profile file during the above c13 pocket TP. Once downloaded upzip in the current working directory.

a. - Thermally Pulsing AGB Star#

Individually/with the person next to you:#

Using the \(3M_{\odot}\) 3m_to_3DU_history.data MESA history dataset:

  1. Plot the log total luminosity \(\rm{log}~L\) and log helium luminosity \(\rm{log}~L_{\rm{He}}\) as a function of star age (star_age) in units of Gyr.

Hint: to zoom in on only the TP-AGB phase, set the xlimits to [1.225,1.227]

  1. Plot the surface abundances of \({^{12}\rm{C}}\), \({^{14}\rm{N}}\), and \({^{16}\rm{O}}\) as a function of star age (star_age) in units of Gyr.

Hint: use the same x -axis limits as part 1.

Hint: if you click the left panel in a jupyter notebook next to a long cell it will hide/unhide the full content to make it shorter to scroll.

  1. Use these two plots the answer/discuss the following questions below with your group.

# load data and see which variables are available
#tp_agb_data = pd.read_csv('##',sep=r'\s+',header=4)
#tp_agb_data.head(10)
#list(tp_agb_data)

# load vars here
#three_m_star_age_years = tp_agb_data['##']
#three_m_log_L = tp_agb_data['##']
#three_m_log_LHe = tp_agb_data['##']

#three_m_surface_c12 = tp_agb_data['surface_#']
#three_m_surface_n14 = tp_agb_data['surface_#'] 
#three_m_surface_o16 = tp_agb_data['surface_#']

## 1 result here
#plt.title('3$M_{\odot}$ Model During TP-AGB Phase')

#plt.plot(##/1e9,
         ##,label=r'$L$')

#plt.plot(##/1e9,
#         ##,label=r'$L_{\rm{He}}$')


#plt.xlim(##

#plt.legend()
#plt.xlabel(r'$\rm{Age \ (Gyr)}$')
#plt.ylabel(r'$\rm{log}~L \ (L_{\odot})$')

## 2 result here
#plt.title('3$M_{\odot}$ Model During TP-AGB Phase')

#plt.plot(three_m_star_age_years/1e9,
#         three_m_surface_###,label=r'$X_{surf.}(^{12}\rm{C})$')

#plt.plot(three_m_star_age_years/1e9,
#         three_m_surface_##,label=r'$X_{surf.}(^{14}\rm{N})$')

#plt.plot(three_m_star_age_years/1e9,
#         three_m_surface_##,label=r'$X_{surf.}(^{16}\rm{O})$')


#plt.xlim(#


#plt.legend()
#plt.xlabel(r'$\rm{Age \ (Gyr)}$')
#plt.ylabel(r'$\rm{Surface \ Mass \ Fraction}$')

With your larger group, try to answer the following:#

Using these plots answer the following:

How many pulses are covered over this range?

Your groups thoughtful response.

What is their qualitative properties over time?

Your groups thoughtful response.

What is the approximate time between pulses, the interpulse period?

Your groups thoughtful response.

Hint: Compare with Pols Figure 11.3/11.4

Does this model experience a third dredge up event during this time? If so, how can we tell?

Your groups thoughtful response.

Does this model show evidence for hot bottom burning (HBB)?

Your groups thoughtful response.

b - Identifying Structure of TP-AGB Stars#

Individually/with the person next to you:#

Using the \(3M_{\odot}\) 3m_c13_pocket_history.data MESA history dataset:

  1. Plot a Kippenhahn diagram using mesaPlot and zoom into the He-shell flash region (about 0.5-0.6 \(M_{\odot}\)) using yrng.

    • To use these data, create a directory called LOGS in the same directory as this notebook

    • Copy 3m_c13_pocket_history.data into the created LOGS directory

    • rename the file in the LOGS directory to history.data

Hint: you might have to install/reinstall mesaPlot like we did in ICA10.

  1. Using your Kippenhahn diagram, answer the following with your group.

## b result here
#import mesaPlot as mp
#m=mp.MESA()
#p=mp.plot()
#m.loadHistory('LOGS')
#kip = p.plotKip(m,show_mass_loc=True,yrng=[##,##])

With your larger group, try to answer the following:#

  1. In the Kippenhahn Diagram, identify the following and state their approximate mass coordinate: the H-burning shell, the He-burning shell, the CO core, the intershell convective zone (ICZ), and the H-envelope.

Your group’s thoughtful response.

c. - the c13 pocket#

Individually/with the person next to you:#

  1. Use the Abund function in mesaPlot to confirm the presence of the formation of a c13 pocket during the interpulse phase for this model.

Hint: Set xmin=0.5787 and xmax=0.579, the ylimit for the abundances to y1rng=[1e-3,1] to zoom in on the pocket!

# c result here
#m=mp.MESA()
#p=mp.plot()
#m.loadProfile(f='LOGS/profile38.data')
#p.plotAbun(m,
#           xmin=##,xmax=##, # set these based on the inspection of the Kipp above
#           cmap=plt.cm.inferno_r,num_labels=10,
#          y1rng=[##,##])

With your larger group, try to answer the following:#

  1. What does the presence of the c13 pocket imply about the observational characteristics of the AGB star?

Your group’s thoughtful response.

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