The synthesis of 26Al, 60Fe and 44Ti in massive stars and their current inventory in our Galaxy

Alessandro ChieffiIstituto Nazionale di AstroFisica (Istituto di Astrofisica e Planetologia Spaziale)

&

Centre for Stellar and Planetary Astrophysics – Monash University - Australia

Email: alessandro.chieffi@iaps.inaf.it

In collaboration with Marco Limongi

Dust in EuroGENESIS environments: from primitive, massive stars to novae Perugia (Italy), November 11-14, 2012

Na22 2.6 Yr 2.842 MeV Ti44 63 Yr 0.268 MeVSc44 3.9 h 3.653 MeVNi56 5.9 d 2.135 MeVCo56 77 d 4.566 MeVCo57 271 d 0.836 MeV

Between 1979 and 2001 several experiments were carried out:

Kretschmer et al. AA 412,47 (2003)

HEAO3

SMM GRIS CGRO

R. DIEHL Clemson 2005 Astronomy with Radioactivities V

On the basis of just the integrated flux towards the galactic center,

the various 26Al sources are:

Type II Supernovae

WR stars

Novae

Intermediate mass stars

Confined in the spiral arms of our Galaxy

Confined within the disk of our Galaxy

10<M<30

30<M<120

1-3<M<7

Kretschmer et al. AA 412,47 (2003)

Plüschke et al.

AIP Conf. Proc. 510

ed. M.L. McConnell & J.M. Ryan

p 35-39 (2000))

1.809 MeV All Sky Map

CGRO

The 53 GhZ free-free all-sky map marks the regions of ionized matter.

A strong ionizing flux (l<912 A) is necessary to mantain matter ionized

(otherwise it would recombine in 1 Myr)

Only stars more massive than, say, 15 MO do produce a strong ionizing flux

hence

The correlation between the 53 GhZ free-free and the 1.809 MeV maps implies that they share the same spatial distribution and therefore that 26Al and ionizing photons

are produced by the same stars

Knodelseder (1999 - ApJ 510, 915) found also that the scaling between the two fluxes is CONSTANT towards all longitudes and equal to:

i.e. 26Al mainly produced by stars more massive than 15 MO

Y26Al = 10-4 MO per O7 V (Log(Qo)=49.05) RGxL = 1.25 10-11 1.8MeV / <912A

RHESSI and INTEGRAL launched in 2002

INTErnational Gamma-Ray Astrophysics Laboratory

Reuven Ramaty High Energy Solar Spectroscopic Imager

60Fe/26AlRHESSI 0.17± 0.05

INTEGRAL 0.14± 0.03

Diehl et al. (2006 – Nature 439,5)

R. DIEHL Clemson 2005

Astronomy with Radioactivities VR. DIEHL Clemson 2005

Astronomy with Radioactivities V

Summary of the observational facts:1) 26Al is very probably produced by stars having M>15 MO

2) There are roughly 1.25 10-11 1.8MeV per ionizing photon at all longitudes

3) The 60Fe/26Al flux ratio is of the order of 0.14 ± 0.05 towards the Galactic center

4) Roughly 2.8 MO of 26Al are present in the Galaxy (± 30%)

The theoretical interpretation is based on our database of evolutions of massive stars:

Limongi and Chieffi (2006 – ApJ 647, 483)

FRANEC (release 5.050419)

O.R.F.E.O. Online Repository for the Franec Evolutionary Output

WEBPAGE: http://orfeo.iasf-roma.inaf.it

WARNING: though the ground and the metastable 26Al states are properly taken into account, for simplicity in the following I’ll simply refer to the total 26Al

26Al production:

1) H convective core

H rich mantle

Central H

burning

2) C (Ne/C) conv. shell (when the star is in shell Si burning)

3) Explosive Ne burning

He burning shell

C convective shell

CO core

Si burning shell

He core

Fe Shock wave

26Al

25Mg24Mg

28Si

26Mg

27Al

29Si

P

N

26Al production in central H burning

The 25Mg is the initial one (usually scaled solar)

H rich mantle

Central H

burning

26Al production in the C (Ne/C) convective shell

26Al

25Mg24Mg

28Si

26Mg

27Al

29Si

P

N

X

M

preservedproduced

22Ne,12C26Al

C profile

CO core

He core

Fe

DESTRUCTION:

12C(12C,)20Ne

12C(12C,p)23Na(,p)26Mg

(CNO)INI 14N(,)18F(+)18O(,)22Ne(,n)25Mg

26Al production in C (Ne/C) convective shell

26Al production by the explosive Ne burning

26Al

25Mg24Mg

28Si

26Mg

27Al

29Si

P

N

23Na

(n,p)

The synthesis of 26Al occurs in the region where the peak temperature drops to Tpeak

2.2 109 K

CO core

He core

Fe Shock wave

T1

T2

r1 r2

Fe core

ignition

Total 26Al yield as a function of the initial mass

H-burn C(C/Ne) shell Explosive Ne burn.

Semi secondary origin

Semi secondary origin

Primary origin

Diehl et al. (2006 – Nature 439,5)

The galactic RGxL The galactic 26Al

By adopting:

mup’ =11MO – Mtop = 120MO

a Galactic Lyman continuum Luminosity QGAL= 3.5 1053 photons/s

)1( xkmdm

dN

2

1

1221

)(m

m x

mmkdm

dm

dNkN

xxmm

2

1

11

122

1 1

)(m

m x

mmkdm

dm

dNmkM

xxmm

)(1

12

21 xx mm

xkm

mN

The galactic 26Al

2

1

2626 )()(

m

mdm

dm

dNmYkAlY

Al

SFRYAlMAl

2626 )(

By adopting:

mup’ =11MO – MSN I I =35MO – Mtop = 120MO

a Galactic Lyman continuum Luminosity QGAL= 3.5 1053 photons/s

Steady state

2 VelorumBinary system containing the closest WR(11) star

Main data taken from Schaerer et al. (1997) and Oberlack et al. (2000)

Distance: 258 pc - WC8 (9 MO) - O8.5III (29 MO)

26Al(Upper limit) => 6.3 10-5 (+2.1-1.4) MO

2 VelorumBinary system containing the closest WR(11) star

Main data taken from Schaerer et al. (1997) and Oberlack et al. (2000)

Distance: 258 pc - WC8 (9 MO) - O8.5III (29 MO)

26Al(Upper limit) => 6.3 10-5 (+2.1-1.4) MO

60Fe57Fe56Fe

60Ni

58Fe

59Co

61Ni

59Fe44 d

P

N

60Fe production: 1) basics

58Ni 62Ni

Central He burning T < 3.5 108 K

22Ne(,n)25Mg

< 107 n/cm3

Central C burning

Main n donor

= few 107 n/cm3

Shell He burning T > 4 108 K => 6 1010 to 1012 n/cm3

crit = 1010 n/cm3

crit = 3 1011 n/cm3

Shell C burning T > 1.3 109 K => 6 1011 to 2 1012 n/cm3

Shell Ne burning T > 1.8 109 K => 6 1011 to 2 1012 n/cm3

T < 109 K

60Fe production: 2) the He and C convective shells

X

M

preservedproduced

22Ne,12C60Fe

He/C

60Fe production: 3) the Ne explosive contribution

The total 60Fe production

M < 60 MO Mainly produced by the C convective shell

M > 60 MO Mainly produced by the C convective shell (Ledoux criterion)

M > 60 MO Mainly produced by the He convective shell (Schwarz. criterion)

The galactic 60Fe/26Al flux ratio

The 60Fe/26Al flux ratio is of the order of 0.14 ± 0.03 towards the Galactic center

)1( xkmdm

dN

Summary & Conclusions

Observational: 26Al is very probably produced by stars having M>15 MO

There are roughly 1.25 10-11 n(1.8MeV)/ (ionizing photon) at all longitudes

The 60Fe/26Al flux ratio is of the order of 0.14 ± 0.05 towards the Galactic center

Roughly 2.8 MO of 26Al are present in the Galaxy (± 30%)

Theoretical: 26Al is mainly produced by the Ne explosive burning.

60Fe is mainly produced by the C convective shell.

The observed (and quite constant) average number of 1.8MeV per ionizing

photon (RGxL) is rather well reproduced by our models.

The observed 60Fe/26Al flux ratio towards the center of our Galaxy is well reproduced if the Langer (1989) mass loss rate in the WNE,WCO is adopted.

Our predictions for 2 Velorum are in agreement with the quoted upper limit and hence the longstanding discrepancy between the data and the predictions is removed.

M(44Ti)=1.6 10-4 MO

M(44Ti)= 3 10-5 MO

Cas A as seen by IBIS – ISGRI aboard INTEGRAL at 25 - 40 KeV

Observed:

Predicted:

Distance 3 Kpc -- 335 yr old -- Mini 30 MO Mend 16 MO

3 lines : 67.9 KeV, 78.4 KeV, 1.157 MeV

(44Ti)= 59.8 yr

44Ti

Not produced in a normal freeze out

Critical phase

Produced in the-rich freeze-out of zones exposed to the complete explosive Si burning

( 3C(,)16O(,)...NSE )

cooling << build upcooling >> build up

42Ca 43Ca 44Ca 46Ca 48Ca40Ca

45Sc

48Ti47Ti46Ti44Ti 49Ti 50Ti

50V 51V

50Cr 52Cr 53Cr 54Cr

55Mn

44TiProduced in the-rich freeze-out of zones exposed to the

complete explosive Si burning

40Ca(,)44Ti

43Sc(p,)44Ti 41Ca(n)44Ti 44Sc(p,n)44Ti

44Ti(,p)47V

26Al

25Mg24Mg

28Si

26Mg

27Al

29Si

P

N

cc

M

jj

ccM

jjj

25j

AVG25

Δm

ρ)Mg(p,Δm

)Mg(p,

γ

γ

26Al production in central H burning: 1) basics

)Al(βY)Mg(p, Y Y Y26

Al26

25

PMg25Al26 γ

26Al production by the explosive Ne burning: 1) basics

26Al

25Mg24Mg

28Si

26Mg

27Al

29Si

P

N

23Na

(n,p)

26Al(n,p) CA88

26Al(n,a) NACRE

26Al production in central H burning: 3) uncertainties

2) the 25Mg(p,)26Al cross section

3) the convective core size

1) the initial 25Mg abundance

many...., but we tested the following:

26Al production in central H burning: 3) uncertainties

1) the initial 25Mg abundance

60 MO

STD 6.94 10-5

25MgINI*2 1.39 10-4

2) the 25Mg(p,)26Al cross section

3) the convective core size (0.3 Hp )

60 MO

STD 6.94 10-5 MO

0.5 HP 5.98 10-5 MO

120 MO

STD 2.82 10-4 MO

0.5 HP 3.50 10-4 MO

α)Al(n,YYp)Al(n,YYγ)Mg(p, YY Y 26NAl26

26NAl26

25PMg25Al26

26Al production by the explosive Ne burning: 4) uncertainties

26Al

25Mg24Mg

28Si

26Mg

27Al

29Si

P

N

23Na

26Mg(,n)29Si 24Mg(n,)25Mg

25Mg(,n)28Si 16O(n,)17O

21Ne(,n)24Mg 20Ne(n,)21Ne

28Al(p,n)28Si 26Al(n,p)26Mg

29Si(,n)32S 26Al(n,)23Na

20Ne(,p)23Na 26Mg(p,)27Al

24Mg(,p)27Al 20Ne(p,)21Na

27Al(,p)30Si 24Mg(p,)25Al

23Na(,p)26Mg 28Al(p,n)28Si

27Al(p,)28Si

25Mg(p,)26Al

30Si(p,)31P

(n,p)

20Ne(,)16O

20Ne(,)24Mg

20Ne(,p)23Na

24Mg(,p)27Al

test 25 MO totalexplosive

60MO totalexplosive

Reference8.61 10-

5

25.2 10-5

26Al(n,p) x 226Al(n,) x 2

6.63 10-

5 -23% -39%19.8 10-5 -21% -50%

24Mg(n,) x 2

11.5 10-

5

+33%

+57% 33 10-5 +31% +60%

25Mg(p,) x 2

11.7 10-

5

+33%

+57%