The chemical evolution
of the Universe
from Big Bang until ~today
Observational Strengths and Weaknesses
Francesca Primas
European Southern Observatory
GCE: just a starting point …
The history of the chemical composition of the
Galaxy is dominated by the nucleosynthesis
occurring in many generations of stars
In each generation, a fraction of the gas will be
transformed into metals and returned to the
ISM (yield, IMF, SFR)
www.stecf.org/coordination/esa_eso/galpops/report.pdf
** Old and metal-poor
(MP, VMP, EMP, UMP, …)
** Nucleosynthesis
Light elements
BBN, CR spallation
Alpha + Iron-group
SN II vs SN Ia, SN imprint
Heavy elements
n-capture (r and s)
cosmo-chronometry
Heraeus Workshop -- Jun 4-6, 2009
How?
1. Search!
High Proper-Motion samples + WF Objective Prism Surveys
2. Follow-up!
@ (low) medium resolution
3. Confirm!
@ high-res
Heraeus Workshop -- Jun 4-6, 2009
Beers, Preston & Shectman
Ryan and Norris, Carney
Christlieb et al
Cayrel et al (2004)
Bonifacio et al (2009)
McWilliam et al (1995)
Before and After: 1st and 2nd revolution
Heraeus Workshop -- Jun 4-6, 2009
Wow!
Abundance dispersion σ=0.05dex!
Cayrel et al. (2004) data
Heraeus Workshop -- Jun 4-6, 2009
What Have We Learned
•well defined trends with low dispersion all the way to the most MP stars
•as spectral quality , the dispersion  :
-- SMALL in most cases: 0.05-0.15dex
-- THINNEST of all: Cr and Ti
-- MOST DISPERSED: Mn ~0.2dex for [Fe/H]<-3
BUT!
~ confirmed also by
the dwarfs …
Ca, Ni, Sr, Ba: OK
Mg, Si: dwarfs 0.2dex lower
Otherwise: 0.2dex higher
(Bonifacio et al 2009)
Heraeus Workshop -- Jun 4-6, 2009
.. by HERES
Heraeus Workshop -- Jun 4-6, 2009
Barklem et al 2005
!
.. and by
everybody
else
!
Fulbright 2000
Johnson & Bolte 2002
Sneden et al 2002
Carretta et al 2002
Cowan et al 2003
Christlieb et al 2004
Cayrel et al 2004
Aoki et al 2005
Lai et al 2008
Bonifacio et al 2009
Heraeus Workshop -- Jun 4-6, 2009
What Can/Should We Improve
---> Data quality is clearly not an issue!
F=160
F=600
F>2000
σ =2.2 (W≤30mÅ)
Heraeus Workshop -- Jun 4-6, 2009
---> Atomic physics and (best) abundance indicators
---> Model atmospheres and theory of line formation
LTE vs NLTE
1D vs 3D
Asplund 2005 (ARAA)
LTE
NLTE
-0.5dex
NLTE from
Mashonkina et al 2000
Heraeus Workshop -- Jun 4-6, 2009
Remember
the
BUT!
about
Mn …
Bergemann 2008
Heraeus Workshop -- Jun 4-6, 2009
CNO
Fe
Collet et al 2006
Heraeus Workshop -- Jun 4-6, 2009
Highlights. I

Cosmology
BBN vs IBBN or even CBBN
The Big Bang gave us H, He,
and a fraction of lithium!

Cosmic-ray physics / Nucleosynthesis
classical, inverse, or neutrino
spallation ?

9Be
10,11B
Stellar structure/interiors
Li
Be
B
6,7Li
T=2.5x106K
T=3.0x106K
T=5.0x106K
Heraeus Workshop -- Jun 4-6, 2009
Stellar Mixing: Li+Be+B
same Li, but different Be and B:
same Li and Be, but different B:
production or destruction ?
production ?
Heraeus Workshop -- Jun 4-6, 2009
Stellar Mixing: Li in GCs
NGC 6397: metal-poor GC (-2.1)
350 stars (+100 in the VLT Archive)
Lind et al (2009)
Heraeus Workshop -- Jun 4-6, 2009
Stellar Mixing: Li in GCs
Lind et al (2009)
Heraeus Workshop -- Jun 4-6, 2009
Highlights.II. The Heavies
McWilliam et al (1995)
Some very metal-poor stars are relatively
rich in neutron-capture elements, and their
abundance pattern indicates dominance of
r-process synthesis.
CS 22892-052
Sneden et al (2003)
3rd peak
Some neutron-capture
elements, especially the
heaviest stable ones of
the “3rd n-capture peak”,
present strong transitions
only in the UV.
Heraeus Workshop -- Jun 4-6, 2009
6 lines in the UV!
Highlights.II
Sneden et al.
HST / GHRS+STIS
r-process rich EMP
1st, 2nd, 3rd peak
cosmo-chronometry
Universal ?
Ag
Nucleo-chronometry: U/Th, U/r, Th/r
Juul Hansen (PhD)
Heraeus Workshop -- Jun 4-6, 2009
Δt = k (log(X/Y)o - log(X/Y)obs)
Highlights.II
Cowan et
al (2005)
Cowan
et al 2005
!
Eu, Os, Ir, Pt:
clear positive correlations
common nucleosynthesis origin
Ge: factors 4-5 lower! Either the r-process does not have anything to do with the creation of
Ge, or these massive neutron blasts pushed all nuclei far beyond the Ge mass range.
Lighter neutron-capture elements have different
nucleosynthetic origins than the elements with Z > 55
Heraeus Workshop -- Jun 4-6, 2009
Highlights.II
CS 31082-001
Hill et al. 2002
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!
Heraeus Workshop -- Jun 4-6, 2009
The Detailed Picture
Sneden et al. 2003
CS 22892-052
Prochaska et al. 2003 Hill et al. 2002
CS 31082-001
Galaxy at z=2.63
Heraeus Workshop -- Jun 4-6, 2009
The Big Picture
Heraeus Workshop -- Jun 4-6, 2009
Johnston 2003
Are we looking in the right place(s) ?
Is the outer halo filled with tidal streams from disrupted
dwarf galaxies that remain coherent in phase space?
ESO Messenger Supplement
Dec 2008
Heraeus Workshop -- Jun 4-6, 2009
Another giant leap forward …
[Ba/Fe]
The pioneering work …
Shetrone, Bolte & Stetson (1998)
[Ca/Fe]
[Ba/Fe]
10 years later …
Large stellar samples
in 5 different dSphs
[Ca/Fe]
Heraeus Workshop -- Jun 4-6, 2009
Large Stellar Samples
Sculptor
Tolstoy et al. 2004
Carina
Battaglia et al. 2006
Monelli et al. 2003
(V-I)
Hill, Venn, et al. 2008
Fornax
(V-I)
Koch et al. 2008
Heraeus Workshop -- Jun 4-6, 2009
Letarte PhD 2007
How?
Firstly, use CaT* (i.e. low-res
spectra) to find the members …
Then get metallicities …
[Fe/H]>-1.7
[Fe/H]<-1.7
HR
Tolstoy et al. 2004
Heraeus Workshop -- Jun 4-6, 2009
And then go for high-res …
Different evolutionary track!
The position of the knee is present at lower
metallicities > slower evolution > SNIa
contribute at lower metallicities
SNII
+SNIa
rise in s-process
s- process: very efficient in galaxies with
strong SFR at younger ages (<5Gyrs):
Fnx > LMC > Sgr > Scl
LMC
Sgr
Fornax
Sculptor
Carina
MW
Tolstoy, Hill, Tosi, 2009, ARAA
Heraeus Workshop -- Jun 4-6, 2009
Pompeia, Hill et al. 2008
Sbordone et al. 2007
Letarte PhD 2007
Hill et al. 2009 (in prep)+ Geisler et al. 2005
Koch et al. 2008 + Shetrone et al. 2003
Venn et al. 2004
The End
but let’s keep observing!
Heraeus Workshop -- Jun 4-6, 2009