ROTATING MASSIVE STAR MODELS: FROM PRIMORDIAL STARS TO HIGH METALLICITY REGIONS

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