ROTATING MASSIVE STAR MODELS: FROM PRIMORDIAL STARS TO HIGH METALLICITY REGIONS
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ROTATING MASSIVE STAR MODELS: FROM PRIMORDIAL STARS TO HIGH METALLICITY
REGIONSGeorges Meynet, André Maeder, Raphael Hirschi and Sylvia Ekstroem
Geneva Observatory
Filaments from Supernovae
Effects of SN in a galaxy: GALACTIC WINDS
Ionising sources, energy and momentum sources, nucleosynthetic sites
Von Zeipel 1924; Eddington 1925; Vogt 1925
An old topic…ROTATION…
Star deformationdue to its fastaxial rotation
… but quite topical nowadays
Link betweenLong GRB and
Hypernova confirmed
Dominiciano de Souza et al. 2003
Hjorth et al. 2003
Cf also van Belle et al. 2003
Nine of 17 O-type stars show a surface enrichment of N up to a solar level, [N]=7.92.
Heap and Lanz 2003; 2005
O-type stars in the SMC
PHYSICS OF ROTATION
STRUCTURE• Oblateness (interior, surface)• New structure equations • Shellular rotation
MIXING• Meridional circulation• Shear instabilities + diffusion• Horizontal turbulence• Advection + diffusion of angular momentum• Transport + diffusion of the chemical elements
MASS LOSS• Increase of mass loss by rotation • Anisotropic losses of angular momentum
GRATTON-
ÖPIK CELL
Cells of meridional circulationVery important
process for thetransport of theangular momentum
Outwards andinwards transportof angular momentum
Occurs when stardeformed…
20 Msol on the ZAMS
r
XDDr
rrt
X ischeareff
i )(1 2
2
rDr
rrUr
rrt
rschear
42
42
2 1
5
1)(
Meridional circulation Gradients of Shear instabilities
Zahn 1992: strong horizontal turbulence, shellular rotation
Transport of the chemical species
Transport of the angular momentum
«
… the radiation observed to be emitted must work
its way through the star, and if there were too much
obstruction it would blow up the star. »
The Von Zeipel theorem (1924)Frad geff
1
12
.
12
1
)(
m
eff
G
gAM
64.0
10
00030
2
06
LL
K
iso mass loss
For stellar formation also
Maeder, 1999 ; cf. Owocki, 1996
STELLAR WINDS & ROTATION
Idem with Teff =25000 K
van Boekel et al. 2003
Meynet and Maeder 2003
New grids of stellar models
Also Z=0.040; 0.008, 0.004, 0.00001
+Pop III
N/C grows during the MS, even forearly B stars (cf.Lyubimkov 1996)
OK with B, A supergiants(cf. Gies & Lambert 1992; Lennon 1994; Venn 1998,…)(cf. Maeder, 1987; Langer, 1992; ….)
300 km/s
200
Gradients of steeper at lower metallicity20 M20 Msolsol, X, Xcc mass fraction of H at the centre, V mass fraction of H at the centre, Viniini= 300 km/s = 300 km/s
Why ? Stars more compact, transport of angular momentum less efficient
Consequences ?More efficient mixing of the chemical elements
9 Msol
When Z
Surfaceenrichments
Venn & Przybilla 2003
Max/ini N/H =40
Max/ini N/H =8
Log (N/H)+128.88.48.07.67.26.86.4
Numberof stars
B/R PROBLEMLots of RSG observed at low Z,but current models predict none.B/R ~ 50 Langer & Maeder, 1995
Models with rotation are OK withB/R = 0.5–0.8 in SMC cf. Maeder & Meynet
2001
NUMBER RATIOS OF MASSIVE STARS
IN NEARBY GALAXIES
M31 0.035 0.24 0.44 1.7
6-7.5
0.029 0.21 0.55 --
7.5-9
0.020 0.104 0.48 ~1
9.5-11
0.013 0.033 0.33 --
M33 0.013 0.06 0.52 ~4
LMC 0.006 0.04 0.20 --
6822
0.005 0.02 -- 8.3
SMC 0.002 0.017 0.11 --
1613
0.002 0.02
GALAXY Z WR/O WC/WR RSG/WR
Conti & Maeder’94;Massey ‘02
For a given metallicity, the minimum initial mass of single stars which become Wolf-Rayet star is decreased for higher rotation velocities
37Msol
22Msol
WR lifetimes alsoincreased for a given initial mass
20Msol
22Msol
25Msol
40Msol
Mmin WNE
Meynet and Maeder 2004
Observed points from Prantzos and Boissier (2003)
Meynet and Maeder 2004
25 Msol: from core H-burning to Si-burning
Hirschi, Meynet, Maeder, 2004
V=0 km/s V=300 km/s
Heger, Langer, Woosley 2000
Pettini et al 2002
Metal-poor dwarfs of theSolar neighborhood
Carbon et al. 1987
HII regions
DLA
Pagel 1997 Garnett 1990
PRIMARYNITROGEN
A newmechanisminduced byrotation
S-process ?
Cf. Herwig et al, 2003
For Z=0.004 and Z=0.020 , nearly no primary N production
At Z= 0, stars are more compact
Feijoo 1999 diploma work
DELTA Log Teff~0.3
PopIII star: radii decreased by a factor 4
Ekström 2004 diploma work
14N
14N
16O 16O
12C 12C
4He 4He1H
1H
25Msol ~30Msol
Mco larger in the rotating model
60 Msol
65.0/ crit.0/ crit
Pop III
Chemical composition of the radiative envelope
PRIMARY 13C and 14N
element Non-rotating
rotating
12C 23.7 Msol 26.5 Msol
13C 1.8E-08 Msol
1.4E-02 Msol
14N 2.4E-07 Msol
5.1E-02 Msol
16O 14.5 Msol 17.25 Msol
CONSEQUENCES FOR NUCLEOSYNTHESIS
Z = 0
Z = 0.00001
Non rotating
rotating
-6.6
New data 2004
Spite et al. 2004Israelian et al. 2004
NEED OF IMPORTANT PRIMARY PRODUCTION BY MASSIVE STARS
MIGHT THE STAR LOOSE MASSBY OTHER PROCESSES ?
Mass loss rates much lowerCf Kudritzki, Hillier
NO M
ASS L
OSS
INITIAL MASS
FIN
AL M
AS
S
Mass loss ratesfrom Vink et al.2000;2001
5.0
)()(
solsol Z
ZZMZM
Vini=300 km/s
Meynet and Maeder 2004
Z= 0.020 Z= 0.004
Z= 0.00001
Vini on the ZAMS= 300 km/s
Vsurf
Age [in My]
Mass Fraction of Hydrogen at the centre
200 Msol
85 Msol
40Msol
60Msol
Pop III stellar models
Mini Mass lost on MS Phase
40 Msol 1 Msol
60 Msol 2 Msol
85 Msol 4 Msol
200 Msol 16 Msol
60 Msol, [Fe/H]=-3.3 and –6.3
Non rotating
Log
Teff
Yc
Rotating
14N
12C
16O
Yc= 0.40
Zsurf/Zini=1
Yc= 0.12
Zsurf/Zini=64
Yc= 0.08
Yc= 0.02
Zsurf/Zini=392
Zsurf/Zini=1336
4He 4He
4He 4He
[Fe/H]=-3.3
Case for[Fe/H]=-6.3Very similar
COMPOSITION OF THE WIND EJECTA
Evolution = f (M, Z, Ω, …)
ROTATING MODELS
Surface enrichements
Blue to red supergiants ratio at low metallicityWolf-Rayet to O-type stars at various
metallicitiesType Ibc to type II supernovae at various metallicities
At low metallicity predict higher enrichments higher velocities
primary Nitrogen
Pulsar rotation rates/GRB progenitorsvery metal poor stars
EFFECTS OF ROTATION AT VERY LOW METALLICITY
ROTATIONAL MIXING
13C and 14N produced in great quantities
May loose half of their initial mass through stellar winds
NUCLEOSYNTHESIS
Pair instability supernovae avoided ?
ROTATIONAL MASS LOSS
Do the models reproduce the observed rotation rate of young pulsars ?
Observed rotation periods of young pulsars: 2ms – 100 ms (20ms)
Middletich et al. 2000; Romani & Ng 2003; Marshall et al. 2003
Pre SN
For NS with P=20ms
25 – 320 X angularmomentum in young pulsars
In pre SN stages, moreefficient angular momentum
Processes ?
Loss of angular momentumduring the collapse ?
Fryer and Warren 2004
COLLAPSAR: Woosley, 2002RelationSN - GRB
Precursor: Rotating WR star ? Is there enough rotation ? 1 % of all WR would be enough.
Hjorth et al. 2003
Conditions for a collapsar
Pre SN
For NS with P=20mms
For NS at break-upWoosley 2003
cm2 s-1
Zsol
To have lost itsH-rich
envelope, to be a WO star (Mhe > 8 Msol->
BH)
WR
To have sufficientangular momentum
But No WO STARS !
ZSMCZsol
WR
Candidates for Collapsars, reduced region at low Z
ZSMCZsol
WR
Candidates for Collapsars, reduced region at low Z
WO
At Z=0.004
~1% of the Core collapsesupernovaeare of type Ic
Conclusions:Evolution = f (M, Z, Ω)
• Evolution of rotational velocities• Lifetimes, tracks• Evolution properties Be, B[e], LBV, WR stars in galaxies• Nebulae• Cepheid properties• Surface abundances in massive stars and red giants• Primary N• Pre – supernova stages• Chemical yields and nucleosynthesis• Rotation periods of pulsars• Final masses• Collapsars, γ- bursts, ….
A correct treatment ofthe transportof angular momentum inall phases is necessary !
If so, high finalang. momentum
Hirschi, Meynet & Maeder, 2004
Age in Myr
300 km/s
800 km/s
MASS LOST DUE TO THE APPROACH OF THE BREAK-UP LIMIT
End MS
0 0.2 0.4
300 0.3 9.3
800 5.8 23.5
Vini
Km/sMass lost
on MS in Msol
Mass lostAfter MS
Effect break-upMdot ~3 10-6 Msol/yr
Redwrads evolutionand CNO enhanced
at the surface
Umeda and Nomoto 2003
Marigo, Chiosi, Kudritzki 2003
Mhe=31; MCO=28 Msol
COMPOSITION OF THE WIND EJECTA
CN
O
F NeNa
MgAl
COMPOSITION OF THE WIND EJECTA
C
NO
F Ne
NaMg
Al
Depagne et al. 2002 CS 22949-037 [Fe/H]~-4
Norris et al. 2001 CS 22949-037 [Fe/H]~-4
Aoki et al. 2002 CS 29498-043 [Fe/H]~-3.75
Christlieb et al. 2004 HE0107-5240 [Fe/H]~-5.3
12C/13C~4
Hypothesis Mfer ~ 0.02 Msol
WIND AND SUPERNOVA EJECTA
CN
O
F
Ne
NaMg
Al
Angular momentum at the pre SN stage
Specific angular momentum in the central part of the star which
eventually will be locked into the compact remnant
ZAMS
End core He-burning
Begin WR phase
Changes of specific angular momentum are only due
to internal transport processes
Decreases as a functionof time
A great part of the decreaseoccurs during the MS phase
120 Msol ini/ fin=40
9 Msol ini/ fin=2.3
Maeder & Meynet 2003
15Msol, Z = 0.02, Vini = 300 km s-1
No magnetic fields
15Msol, Z = 0.02, Vini = 300 km s-1
With magnetic fields
MAGNETIC FIELDS ?
According to Heger et al. 2004 magnetic braking can slow down the coreby about an order of magnitude.Help but still insufficient
No long surface enrichments
15Msol, Z = 0.02, Vini = 300 km s-1
No magnetic fields
15Msol, Z = 0.02, Vini = 300 km s-1
With magnetic fields
New models with magnetic fields accounting for a local energy condition
The energy for building the magnetic field is extracted from theenergy in the differential rotation
The amplitude of the magnetic field is determined by the energyavailable in the shear in the zone where it develops.
In preparation
Magnetic field appears mainlyin the outer parts of the star(inhibiting effect of the gradientof the mean molecular weight)
Evolution with magnetic fieldvery similar to that obtainedwithout magnetic field
These results would favour theloss of angular momentum atthe time of collapse for accountingthe observed rotation rate of youngpulsars
Gies & Huang 2003
ROTATION AND ASTEROSEISMOLOGY
2
~,,
0,,,,mln
lnmln m
Xc=0.33 Xc=0.44
Hz
Hz
Eggenberger 2003
Determination of Rotation changes the valuesof the small separation
Has rotation an impact on the quantity of 26Al released ?
cf Langer et al. 95 Vuissoz et al., in preparation
Quantity of 26Al ejectedby the winds is increasedby rotation
Effect different from anenhancement of the mass loss rate
Vini 0 km/s 300km/s 500km/s
M(26Al)10-4 Ms
1.30 2.18X 1.68
2.61X 2.00
Knödlseder et al. 2002 in Cygnus region models underestimate26Al production by about a factor 2
Pettini et al 2002
Metal-poor dwarfs of theSolar neighborhood
Carbon et al. 1987 HII regions
DLA
Adapted by Pagel 1997from Garnett 1990
See also Matteucci and Tosi 85 Matteucci 86
Increase of primary N production when rotation increases
Prantzos 2003
Contribution from rotation of the same orderof magnitude as contribution from classical models of thermal pulse AGB stars.
See also Carigi 2003; Chiappini et al. 2003
Z=0.004
At lower Z, more stars reach break-up velocities. PARADOXICAL !
SHORT EJECTIONPeanut shaped nebulae
1
12
.
12
1
)(
m
eff
G
gAM
Maeder,1999
cf also Owocki et al. 1996
Fast rotating hot stars havePolar winds
When Z decreases stars become morecompact
In U the Gratton Öpick scales with theInverse of the density
Less angular momentum is removedby the stellar winds
?
Ekstroem, Meynet, Maeder in preparation, cf Marigo, Chiosi, Kudritzki 2003
600 km/s
175 km/s
300 km/s
300 km/s
End core Si-burning phase HIRSCHI 2004
IN ROTATING MODEL More massive Si-core
V = 0 MSi= 1.6 Msol V=300 MNe= 2.2 Msol
Slightly more massive Ni-core
V = 0 MNi= 1.1 Msol V=300 MNe= 1.25 Msol
Christlieb et al. 2004 HE0107-5240 [Fe/H]~-5.3
Depagne et al. 2002 CS 22949-037 [Fe/H]~-4
Norris et al. 2001 CS 22949-037 [Fe/H]~-4
Aoki et al. 2002 CS 29498-043 [Fe/H]~-3.75
COMPARISON WITH C-RICH EMP STARS
F
Ne