Homework 7 Solutions

Queson 1b 3b 4he 16o 12c like h and he o and c

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: eac%on becomes more vigorous and nearly all the 3He is destroyed. ques%on 1b 3(b) 4He 16O 12C Like H and He, O and C abundances remain at their photospheric level down to the tachyocline due to convec%ve mixing, then “bump up” in the radia%ve zone due to gravita%onal seJling (there is a slight nega%ve slope in the rela%ve abundances down to 0.2 R). In the fusing core, 4He increases for the reasons given in the previous problem. 12C declines sharply at it is consumed by the rela%vely fast and rela%vely low Coulomb barrier reac%on 12C + 1H -­‐> 13N in the CNO cycle, but not replenished by the higher Coulomb barrier 15N + 1H -­‐> 12C reac%on, nor by the triple alpha process 4He + 4He + 4He -­‐> 12C due to that reac%on’s low probability at low temperatures (remember, reac%on rates for triple alpha scale as T41!). 16O abundance decreases only slightly in the center of the Sun due to the rare 16O + 1H -­‐> 17F CNO reac%on; the high temperature (high...
View Full Document

This document was uploaded on 02/26/2014 for the course PHYS 160 at UCSD.

Ask a homework question - tutors are online