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

density

molecular cloud analog (200 K)

shock

600 pc

The previous slide shows snapshots of a 3D hydrodynamical simulationof the formation of the first stars. Dark matter first condenses and thenforms 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 shownon 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 gravitationallybound. Within this core a dense knot of about 1 Msun has formed (yellow regionof 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 about300 solar masses before accretion is shut off by the stellar luminosity.

Baraffe, Heger, and Woosley, (2001), ApJ, 550, 890

nb. Even Z=0 stars burn hydrogen by the CNO cycle. T ~ 108 K

astroph-0112059

Heger and Woosley, (2002), ApJ, 567, 5332

At 133, without rotation, begin making massive back holes

Helium core Neutron excess

Yields of the dominant elements (left scale) and explosion energy(right scale) as a function of helium core mass. Helium cores ofhigher mass collapse to black holes.

Those that make large abundances of 56Ni will be exceptionally brilliant.

oxygen

Ni

KE

Each supernova of this type injects about 50 solar masses into the “interstellar medium”. This is enough to provide a metallicity [Z] = -4to 25 million solar masses of material, more than the proto-galactic fragments Abel et al. calculate.

Ordinarily a neutron excess is created during helium burning by

Ne),( O)(e F),( N 22181814

but in a star that has no initial CNO there is no 14N presentin helium burning.

Collapse then occurs before carbon or neon burning couldcreate neutrons by other weak interactions. Consequently thesestars have no r- or s-process and have trouble making elementswith odd Z.

During the collapse sufficient electron capture occurs, especiallyin the more massive models, to make odd-Z elements in the iron group.

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.

Heger & Woosley, (2002), ApJ, March 1.

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 persquare degree every 3 days. 1000 might be visible per square degree.Wavelengths beyond the IGM Ly-alpha absorption (2.55 micons) are displayed asdotted lines. The first bump is shock break out. The long second one is the plateau.

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.