identify LMS
rad core, conv env
effect of degenerate core
SC limit not imp, core mass can inc
no rapid core contraction
so hertz sprung gap
SUMMARIZE STEPS
AB—MS (H—> He center)
BC—subgaint (H—> He shell, center T inc, core contract)
D— dredge up (conv till core)
DE—RGB (outer layers rmv, M_core inc, T_core inc, shell burn = T_core inc )
E—He flash (from center, T~10^8 K, high L_core, lifts degeneracy, density dec)
subflashes
Horizontal branch—density dec, T dec, cooling–stable helium burning–const Lum
at what point core degenerate
C
what point fully convective?
C (lect)
D (book)
what causes He flash
He ignition needs temp 10^ 8 K
H shell burn inc temp, core contract (coz degeneracy lifted???)
He flash effect of neutrinos release
neutrinos emit from v centre
T_center dec
He burn in cen stops
He burn in shell
He flash effect on neutrinos release
neutrinos emit from v centre
T_center dec
He burn in cen stops
He burn in shell
Whats He runaway?
Rxn highly temp dependent,
E released v fast
T_core inc fast
R_core ~ cont (coz T inc fast n degenerate core can’t expand)
more E then can be released—-He runaway
He flash lum?
degen core-- lum inc, T inc density ~const E not released till surface, E absorbed by core n env E used to lift degeneracy now density dec
after He flash
E from He flash doesn’t reach surface, it is used in expansion of non-degenerate layers above it, R inc– T dec– stable He burning
phase after He flash
horizontal branch
stable burn of He in core
H burn in shell
why called horizontal branch
L dependent on M_core
M_core ~const— 0.47 solar M
so L~const
how is M_core~const with mass loss rate eta = diff?
eta= rmv envelopes not core
so LMS have at this point same M_core, diff total M
which Horizontal branch *s haven thicker env?
red
