Abel, Bryan, and Norman, 2002, Science, 295, 5552

1
Abel, Bryan, and Norman, (2002), Science, 295,
5552
600 pc
density
shock
molecular cloud analog (200 K)
2
The previous slide shows snapshots of a 3D
hydrodynamical simulation of the formation of the
first stars. Dark matter first condenses and
then forms potential wells into which
pre-galactic objects accumulate. The gas cools
through vibration and rotational bands of the H-2
molecule. The bottom two rows show slices
through the last simulation shown on the top row.
The lower right panel shows a molecular cloud (T
about 200 K) with a dense core a few hundred K
hotter. This core is gravitationally bound.
Within this core a dense knot of about 1 Msun has
formed (yellow region of the red spot in the
right panel of the second row). Recent
calculations reported by Omukai and Palla (ApJ,
561, L55, (2001)) suggest that the fragments in
the calculations of Abel et al will grow to
about 300 solar masses before accretion is shut
off by the stellar luminosity.
3
Baraffe, Heger, and Woosley, (2001), ApJ, 550, 890
nb. Even Z0 stars burn hydrogen by the CNO
cycle. T 108 K
4
astroph-0112059
5
Heger and Woosley, (2002), ApJ, 567, 5332
Helium core
Neutron excess
At 133, without rotation, begin making massive
back holes
6
oxygen
KE
Ni
Yields of the dominant elements (left scale) and
explosion energy (right scale) as a function of
helium core mass. Helium cores of higher mass
collapse to black holes. Those that make large
abundances of 56Ni will be exceptionally
brilliant.
7
Each supernova of this type injects about 50
solar masses into the interstellar medium.
This is enough to provide a metallicity Z
-4 to 25 million solar masses of material, more
than the proto- galactic fragments Abel et al.
calculate.
8
Ordinarily a neutron excess is created during
helium burning by
but in a star that has no initial CNO there is no
14N present in helium burning.Collapse then
occurs before carbon or neon burning could create
neutrons by other weak interactions. Consequently
these stars have no r- or s-process and have
trouble making elements with odd Z. During the
collapse sufficient electron capture occurs,
especially in the more massive models, to make
odd-Z elements in the iron group.
9
Heger Woosley, (2002), ApJ, March 1.
Production factors for very massive stars (65-130
solar mass helium cores corresponding to main
sequence masses of 140 - 260 solar masses)
integrated over an IMF and compared with solar
abundances. The integration assumed a Salpeter
IMF with three different slopes (-.05, -1.0,
-1.5). Zero r- and s-process.
10
Light curve of a 250 solar mass pair instability
supernova at a red shift of 20. If 10(-6) of the
baryons go into stars like this, one expects one
explosion per square degree every 3 days. 1000
might be visible per square degree. Wavelengths
beyond the IGM Ly-alpha absorption (2.55 micons)
are displayed as dotted lines. The first bump is
shock break out. The long second one is the
plateau.
11
Fryer, Woosley, and Heger (2001), ApJ, 550, 372
300 solar mass star, 180 solar mass helium core.
Makes black hole. Include rotation. Redshift 20.
Star initially forms a 50 Msun core with r about
1000 km. Neutrinos trapped. Possible rotational
instability and gravity wave emission (EGW
0.001 M c2). Later a 130 solar mass black hole
accretes about 30 solar masses through a disk at
a rate 1 10 solar masses per second. Up to 1054
erg might go into a jet.