evo: LMS Flashcards
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
