1. Spallation l-process (spallation):
D, Li, Be, B destroyed in stars: Low binding energies, burn quickly to heavier nuclei.
But … D close to Big Bang predictions Higher Li, Be, B often observed. Why?
l-process (spallation):
Accelerate nucleus to v ~ c (e.g. cosmic rays) Collide with a stationary nucleus. Splits yield Li, Be, B.

2. BB 1,2H 3,4He 7Li Intergalactic medium Interstellar medium SN?
Galaxy formation inflow
Gal. winds, stripping, mergers
Interstellar medium
Spallation 6Li, Be, B
Cosmic rays
Star formation
Winds, PN, Novae He, 7Li, C, N D, Li, Be, B
Explosive r-process
Small stars D, Li
Middling stars
Big stars SN
NS BH WD

3. X-rays from Supernova remnants
Shocked gas hot enough to emit X-rays

4. More ways to enrich the ISM
Stellar winds: radiation pressure blows gas from the surfaces of hot massive stars.
Can be very eruptive!

5. Planetary Nebula: matter ejected from 1-3 solar mass star at end of the AGB phase
Animation of the formation of the Helix nebula

6. Planetary Nebulae

7. Lecture 9: Supernova Rates Star-Formation Efficiency, Yield
How many supernovae per year for each galaxy type?
Use power-law IMF, Salpeter slope -7/3 = -2.33
Limits of validity, not well known . .
slope = . .
0.1M . 8M
20M
Supernova limit

8. Integrating a Power-Law IMF
Number of stars :
Fraction of stars with M > 8 M
500 stars --> 1 supernova! .
Most stars at low-mass end!

9. SN Mass Fraction SNe are rare, but each is very massive.
What fraction of the mass goes into SNe?
Most of mass is in low-mass stars.

10. Typical SN Mass
Median mass:
Mean mass: .

11. SN Rates: Spiral Galaxy: SFR: ~ 8 M yr-1. 7.2% have M > 8M . . .
8 x ~ 0.6 M yr-1 go into SNe
SN rate:
Irregular Galaxy: ~10x this rate during bursts (1 SN per 2 yr)!
No SNe between bursts. . . . . .

12. SNe in Ellipticals t* = 1 Gyr e-folding time t = 10 Gyr age
a = efficiency
M0 = 1011 M total mass = initial gas mass
Gas consumption:
Star formation:
SN rate:
3 SN per 105 yr. Negligible! . . . .

13. What Efficiency and Yield?
X = 0.75
Y = 0.25
Z = 0.00
X = ?
Y = ?
Z = ?
MG = 1
MS = 0
MG = 0
MS = 1
MG = ?
MS = ?
KABOOM!
KABOOM!

14. Estimates for efficiency a , yield in X, Y, Z
Assume:
Type-II SNe enrich the ISM. Ignore: Type-I SNe, stellar winds, PNe, ....
Ignore: Infall from the IGM.
SN 1987A is typical Type-II SN.
Better models include these effects.
What we know about SN 1987A?

15. SN 1987A 23 Feb 1987 in LMC Brightest SN since 1604!
First SN detected in neutrinos.
Visible (14 --> 4.2 mag) to naked eye, in southern sky.
Progenitor star visible: ~20 Msun blue supergiant.
3- ring structure (pre-SN wind)
Shockwave now hitting inner ring.

16. SN 1987A

17. Star Formation Efficiency
Use SN 1987A to calculate a and yield.
SN 1987A: initial mass = 20 M
NS mass = 1.6 M
From IMF, 7.2% of MS is in stars with M > 8 M
Fraction of MS returned to ISM:
Efficiency = fraction of MS retained in stars. . . .

18. Yields in X, Y, Z Initial mass ~ 20 M NS mass ~ 1.6 M
Mass ejected ~ 18.4 M
in H 9.0 M
He 7.0 M = 18.4 M
Z 2.4 M . . . . . . .