3. When a star is on the Horizontal brunch it burns Helium via triple alpha reactions. Dur- ing a triple alpha reaction we know that 3 Helium are transformed into Carbon as in 3 x He 12 C. Estimate the duration of the horizontal branch phase in a 2M star through the following steps: (a) Compute the energy released in a net triple alpha reaction. (b) Assume that at the beginning of the horizontal branch phase, 15% of the original mass of the star is in the form of 4He in the stellar core. Estimate the total energy released by fusing this amount of helium into carbon via the triple-alpha process. (c) Assume that during the horizontal branch phase L = 175L. If all this luminosity is provided by the fusion of helium to carbon in the core, how long (in years) will the horizontal branch last?
3. When a star is on the Horizontal brunch it burns Helium via triple alpha reactions. During a triple alpha reaction we know that 3 Helium are transformed into Carbon as in $3 \times{ }^4 \mathrm{He} \rightarrow{ }^{12} \mathrm{C}$. Estimate the duration of the horizontal branch phase in a $2 M_{\odot}$ star through the following steps:
(a) Compute the energy released in a net triple alpha reaction.
(b) Assume that at the beginning of the horizontal branch phase, $15 \%$ of the original mass of the star is in the form of ${ }^4 \mathrm{He}$ in the stellar core. Estimate the total energy released by fusing this amount of helium into carbon via the triple-alpha process.
(c) Assume that during the horizontal branch phase $L=175 L_{\odot}$. If all this luminosity is provided by the fusion of helium to carbon in the core, how long (in years) will the horizontal branch last?
Step by step
Solved in 2 steps
