Estimate thehydrogen-burning lifetimes of stars near the lower and upper endsof

Question

Estimate thehydrogen-burning lifetimes of stars near the lower and upper endsof the main sequence. The lower end of the main sequence occursnear 0.072Msun, with log10Te=3.23and
log10(L/Lsun)=-4.3. On the other hand, an 85Msun star near the upper end of the main sequence has aneffective temperature and luminosity oflog10Te=4.705 andlog10(L/Lsun)=6.006, respectively. Assumethat the 0.072Msun star is entirely convective so that,through convective mixing, all of its hydrogen, rather than justthe inner 10%, becomes available for burning. Estimate thehydrogen-burning lifetimes of stars near the lower and upper endsof the main sequence. The lower end of the main sequence occursnear 0.072Msun, with log10Te=3.23and
log10(L/Lsun)=-4.3. On the other hand, an 85Msun star near the upper end of the main sequence has aneffective temperature and luminosity oflog10Te=4.705 andlog10(L/Lsun)=6.006, respectively. Assumethat the 0.072Msun star is entirely convective so that,through convective mixing, all of its hydrogen, rather than justthe inner 10%, becomes available for burning.

Explanation / Answer

Life time of star = E /10-4.3L                            =m * c2 /10-4.3L                           = 0.072Msun * c2 /10-4.3L For the 85 M star , only 10% isavialable for fusion because it is not fully convective. Life time of star = E /10-4.3L                            =m * c2 /10-4.3L                           = 0.1 * 85Msun * c2 /10-4.3L I hope this helps you. For the 85 M star , only 10% isavialable for fusion because it is not fully convective. Life time of star = E /10-4.3L                            =m * c2 /10-4.3L                           = 0.1 * 85Msun * c2 /10-4.3L I hope this helps you. I hope this helps you.

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