1. Pair Instability Supernovae
Lecture 19
Pair Instability Supernovae
and
Population III

2. Mass Loss in Very Massive Primordial Stars
Negligible line-driven winds (mass loss ~ metallicity1/2) (Kudritzki 2002)
No opacity-driven pulsations (no metals)
Continuum-driven winds likely small contribution
Epsilon mechanism inefficient in metal-free stars below ~1000 M (Baraffe, Heger & Woosley 2000) from pulsational analysis we estimate upper limits:
120 solar masses: < 0.2 %
300 solar masses: < 3.0 %
500 solar masses: < 5.0 %
1000 solar masses: < 12.0 %
during central hydrogen burning
Red Super Giant pulsations could lead to significant mass loss during helium burning for stars above ~500 M

3. Can very massive stars retain their mass
even today?
The Pistol Star
Galactic star
Extremely high mass loss rate
Initial mass: 150 (?)
Will die as much less massive object

4. Eta Carina Thought to be over 100 solar masses Giant eruption in 1843.
Supernova-like energy
release. 2nd rightest star
in the sky. V = -0.8
solar masses of
material were ejected
in less than a decade.
8000 light years distant.
Doubled its brightness
in Now
visble V = 4.7.

5. (M> 40 solar masses)
Pair instability
Barkat, Rakavy and Sack (1967)
(M> 40 solar masses)
Helium core mostly convective and radiation a large part of the total pressure.~ 4/3. Contracts and heats up after helium burning. Ignites carbon burning radiatively
Above 1 x 109 K, pair neutrinos accelerate evolution. Contraction continues. Pair concentration increases. Energy goes into rest mass of pairs rather than increasing pressure,  < 4/3. Contraction accelerates.
Oxygen and (off-center) carbon burn explosively liberating a large amount of energy. At higher mass silicon burns to 56Ni
The star completely, or partially explodes

6. Nomoto and Hasimoto (1986)
Helium stars

7. Pair-Instability Supernovae
Many studies in literature since more than 3 decades, e.g.,
Rakavey, Shaviv, & Zinamon (1967)
Bond, Anett, & Carr (1984)
Glatzel, Fricke, & El Eid (1985) Woosley (1986)
Some recent calculations: Umeda & Nomoto 2001
Heger & Woosley 2002
Pulsational Pair
Supernovae
Pair instability
Supernovae
Rotation reduces these
mass limits!
Mass loss alters them.
Black holes

9. Ejected “metals”

10. Elemental production factor in a Pop III 15 M star
primordial initial composition

11. Elemental production factor in a 25 M star
primordial initial composition

12. Elemental production factor in a 35 M star
fallback
primordial initial composition

13. “Standard model”, 1.2 B, = 1.35, mix = 0.1, 10 - 100 solar masses

14. Best fit, 0.9 B, = 1.35, mix = 0.0158, 10 - 100 solar masses

15. 28 metal poor stars in the Milky Way Galaxy
Lai et al. 2008, ApJ, 681, 1524
28 metal poor stars in the Milky Way Galaxy
-4 < [Fe/H] < -2; 13 are < -.26
Cr I and II, non-LTE effects; see also
Sobeck et al (2007)

16. Production factor of massive Pop III stars
– “standard” mixing included

17. (Frebel)

19. Church et al (2009, submitted). Mixing depends on RSG or BSG
nature of progenitor and hence rotation and metallicity

20. Umeda and Nomoto, Nature, 422, 871, (2003)

22. (Christlieb)

23. Pair Instability Supernovae
Nucleosynthesis from
Pair Instability Supernovae
Heger and Woosley (2002)

24. Initial mass: 150M

25. Initial mass: 150M

26. Initial mass: 250M

27. Initial mass: 250M

28. Big odd-even effect and deficiency of
neutron rich isotopes.
Star explodes right after helium burning
so neutron excess is determined by initial
metallicity which is very small.

30. Production factor of massive and very massive Pop III stars

32. Shock break-out in pair-instabilty supernovae
Kasen and Woosley (2009, in preparation)

33. Spectrum of shock break-out
( R = RSG, B = BSG)

34. Light curves of pair instability
sueprnovae in their restframe

35. Compared with a typical SN Ia (red SN 2001el), a Type Iip
(blue. SN 1999em) and the hypernova SN 2006gy (green)

36. Red-shifted light curve of a bright pair-instability SN

37. Spectra near peak light

38. Instability Supernovae
Pulsational Pair
Instability Supernovae

40. Onset of
instability
At end of
first pulse

41. After 2nd
pulse
At final
point

42. Velocity and enclosed mass after second mass
ejection solar mass model (74.6 at explosion)

43. Light curves of the two outbursts (110 solar mass model)

45. Absolute R-band magnitudes
of the 110 solar mass model
compared with obsevations of
“hypernova” SN 2006gy.
Instabilities will smooth
these 1 D calculations.
The brighter curve assumed
twice the velocity for
all ejecta. (7.2 x 1050 erg
becomes 2.9 x 1051 erg)
Woosley, Blinnikov and Heger (2007,
Nature, 450, 390)

47. 238 million light years away