Loading in 2 Seconds...
Loading in 2 Seconds...
Abundance Patterns to Probe Stellar Nucleosynthesis and Chemical Evolution. Francesca Primas. Setting the Stage. 1. High-z universe, i.e. looking at objects in their infancy stages. DLA: dominant reservoir of neutral baryons measure the mean metallicity in HI (5< z < 0).
1. High-z universe, i.e. looking at objects in their infancy stages
2. Nearby universe, i.e. looking at the fossilized imprint left by the first generations of stars
Identify the imprint left by the first SNe explosions
[Fe/H] = log(Fe/H)* - log(Fe/H)sun
BBN, CR spallation
alpha and iron-group
SN physics (time delays) and SN imprint
Li Be B
(670.7nm, 313.0nm, 250.0nm)
BBN vs IBBN (Li)
classical spallation (Reeves et al. 1970) ?
primary ? neutrino-spallation (11B) ?
Cayrel et al. (2004) data
HE 0107-5240 ([Fe/H]=-5.3)and HE 1327-2326 ([Fe/H]=-5.5
(large[C/Fe], but different in N, Na, Mg, Al)
C-rich metal-poor stars: 20-30% (?)
r-process rich stars
Sneden et al. 2003
Hill et al. 2002
Galaxy at z=2.63
Prochaska et al. 2003
1. Does Os really deviate from the solar r-process pattern ?
Not anymore after new gf value (Ivarsson et al. 2003) ==> Os=Ir
2. Still missing input atomic physics for Ho, Lu, and Yb!
--->Atomic physics and (best) abundance
--->Model atmospheres and theory of line
LTE vs NLTE
1D vs 3D
Asplund 2005 (ARAA)
Collet et al 2006
EMP = old ?? Not quite, presumably old ==> age
In r-process rich stars:
Dt = 46.67(log(Th/S)o - log(Th/S)obs )
Problem: evaluation of the log(Th/S)o based on the
assumption that the r-process is universal
[ cf. Cowan (pro) and Goriely (con) ]
Warning: actinides and lower-mass r-nuclei may vary strongly (despite the constancy for Z=56-82)
[ cf. Hill et al. 2002, Honda et al. 2003]
Th (and U) seem to be over-abundant:
log(Th/Eu) = -0.22 (wrt ~ -0.6! for similar stars)
Age difference ?NO, otherwise CS 31082-001 would have a
negative age, compared to the other n-rich stars !
Ab initio enhancement ?IF SO, r-process may not be universal !
Th/Eu =? a reliable chronometer
CS 31082-001:Th and U were detected and used
Dt = 21.76(log(U/Th)o - log(U/Th)obs)
+similar ionization and excitation potentials --> errors largely cancel out
+ initial production ratio: more robust against variations in n-exposure
(nuclear reaction network code containing more than 3500 isotopes with all relevant reactions! )
Nilsson et al. 2002a,b
Goriely & Arnould 2001
8 Th lines, each with gf determined better than 0.08dex
1 U line with gf determined better than 0.06dex
log(U/Th)o = 0.50 (0.02)
Age = 14.0 +/- 2.4 Gyr
log(U/Th)obs = -0.74 (0.15) … -0.94 (0.11)