MMupup

Oscar StranieroOscar Straniero&&

Luciano PiersantiLuciano Piersanti------------------

INAF - Osservatorio di TeramoINAF - Osservatorio di Teramo

Becker and Iben 1979Becker and Iben 1979

where: Zo=0.02

Yo=0.28

Status of the artStatus of the art

CLASSICAL MODELS CLASSICAL MODELS (bare Schwarzschild (bare Schwarzschild

criterion)criterion)

In order of appearance

:

Siess 2007versus

Becker Iben formula 1979

(same Z,Y than Siess)

Beyond the core He Beyond the core He burning: the early-burning: the early-

AGBAGB

CO

H-rich

He

-cooling

H burning

He burning

Conv. Env.

The golden ruleThe golden rule It exists a critical-core mass for the C It exists a critical-core mass for the C

ignition.ignition. It is MIt is MHH~1.08 M~1.08 Mʘ ʘ (with the “current” physics).(with the “current” physics).

To evaluate MTo evaluate Mupup, we have to take under control:, we have to take under control: The physics of the C ignition: neutrinos, The physics of the C ignition: neutrinos,

12C+12C, amount of C left (12C+12C+12C, amount of C left (12C+), ), thermodynamics of a dense plasma (EOS)… .thermodynamics of a dense plasma (EOS)… .

The initial-to-final mass relation for an The initial-to-final mass relation for an intermediate mass stars (5 - 9 Mintermediate mass stars (5 - 9 Mʘʘ), which ), which depends on:depends on:

1.1. The extension of the H-exhausted core at the end The extension of the H-exhausted core at the end of the MS phase.of the MS phase.

2.2. The duration of the core-He burning phase (when The duration of the core-He burning phase (when H is burned in shell).H is burned in shell).

3.3. The efficiency of the 2nd dredge up.The efficiency of the 2nd dredge up.

Varying the convective Varying the convective schemescheme

Classical

Overshoot Semi Convection

Classical versus Classical versus Semiconvection (core-He Semiconvection (core-He

burning)burning)

≈0.9 Mʘ≈

In order of appearance:

Siess 2007

versus

Straniero et al. 2003 , see also Dominguez et

al. 1999

Classical versus Overshoot Classical versus Overshoot

In order of appearance

:

Siess 2007 (squares)

versus

Girardi 2000

(triangles)

Both: OV (red) noOV

(black)

Siess07 OV

≈1.6 Mʘ

≈1.7 Mʘ?

Semiconvection versus Semiconvection versus overshootovershoot

In order of appearance:

Straniero et al. 2003

(semiconv.)

versus

Siess 2007 (overshoot)

≈0.7 Mʘ

Varying the composition Varying the composition (Y)(Y)

Larger HeLarger He larger larger larger Tlarger TCC larger CC larger CC larger final M larger final MH H and, then: and, then:

SMALLER SMALLER MMUPUP

YY MMUPUP

0.290.29 9.59.5

0.340.34 8.78.7

0.370.37 7.77.7

Z=0.04, Bono et al. 2000

Varying the composition Varying the composition (Z)(Z)

Larger Z Larger Z larger (external) larger (external) and more expanded and cooler structuresand more expanded and cooler structures

BUTBUT

Larger Z Larger Z more CNO and more efficient H-burning more CNO and more efficient H-burning

Z> 10Z> 10-3 -3 Z Z

MMUPUP

1010-5-5<Z< 10<Z< 10-3-3 Z Z

MMUPUP

Z< 10Z< 10-5 -5 Z Z

MMUPUP

Varying the composition Varying the composition (Z)(Z)

Approaching the C Approaching the C ignition ignition

nuclear=|

Varying the neutrino rateVarying the neutrino rate ()

In order of appearance:

Esposito et al. 2003 (same for Haft et al 1995

or Itoh et al. 1996)

versus

Munakata et al. 1986

Varying Varying or X(12C)

x5

/5

Equivalent to a reduction/multiplication of X(12C) by sqrt(5) (0.1 to 0.6), the range of uncertainty implied by the 12C+16O see

Straniero et al. 2003)

Varying the Varying the 1212C+C+1212CC Laboratory measurements available down to Laboratory measurements available down to

about 3 MeV (the Gamow peak for Mabout 3 MeV (the Gamow peak for Mupup is 1.5 is 1.5 MeV).MeV).

Several evidences of “molecular” structure Several evidences of “molecular” structure producing narrow resonances at low energy (see producing narrow resonances at low energy (see Wiescher 2007, Spillane et al. 2007, Cooper et al. Wiescher 2007, Spillane et al. 2007, Cooper et al. 2009).2009).

A (possible) resonance near the Gamow peak A (possible) resonance near the Gamow peak would significantly increase the rate, thus would significantly increase the rate, thus reducing both the critical Mreducing both the critical MHH and, in turn, M and, in turn, Mupup

Co

re

bu

rnin

g

SN

e Ia

What a resonance at 1.5 MeV would imply

M=7M

Z=Z

(dashed line)

Mup

ZZ CF88CF88 NEWNEW

0.00010.0001 6.66.6 4.54.5

0.00100.0010 6.76.7 4.74.7

0.00600.0060 7.27.2 5.35.3

0.01490.0149 7.87.8 5.85.8

0.02980.0298 8.38.3 6.16.1

Mup reduces of ~2 M

Astrophysical Astrophysical Consequences of Consequences of

a variation of Ma variation of Mupup

(numbers will be given for a (numbers will be given for a

MMupup~2 M~2 Mʘ)

Astrophysical Astrophysical consequences Iconsequences I

The number of super-AGB (ONeMg WD The number of super-AGB (ONeMg WD or electron-capture SNe) is larger.or electron-capture SNe) is larger.

By adopting a (Salpeter like) power-low By adopting a (Salpeter like) power-low IMF (IMF (=2.35), SAGB would be 2/3 of =2.35), SAGB would be 2/3 of the stars with M>M_up’ (the the stars with M>M_up’ (the progenitors of “normal” core collapse progenitors of “normal” core collapse SNe). SNe).

3

1,

3

1,

3

2

CCSN

SAGB

N

N

1.5 MeV resonance, semiconv., classical mod.

Astrophysical Astrophysical Consequences IIConsequences II

Massive CO WDs cut off: MMassive CO WDs cut off: MWDWD max max reduced down to 0.95 Mreduced down to 0.95 Mʘʘ).).

BUT ROTATION MAY HELP see Dominguez et

al 1996

Massive CO WD: Massive CO WD: the lifting effect the lifting effect

of rotation of rotation delays the II delays the II dredge up, dredge up,

allowing more allowing more massive Mmassive MHH

(Dominguez et al. (Dominguez et al.

1996)1996)

Convective envelope

He-rich zoneCO core

6.5 Mʘ Z= Zʘ

Astrophysical Astrophysical Consequences IIIConsequences III

Less Massive AGB Less Massive AGB less space left less space left for Hot Bottom Burningfor Hot Bottom Burning

Astrophysical Astrophysical Consequences IVConsequences IV

SN Ia rates, both SN Ia rates, both scenarios, Single scenarios, Single Degenerate and Degenerate and Double Degenerate, Double Degenerate, 4 times less 4 times less frequent!!frequent!!

Prompt SNIa Prompt SNIa suppressedsuppressed

First SNe Ia First SNe Ia delayeddelayed

(see Piersanti et al. (see Piersanti et al. 2010)2010)

Astrophysical Astrophysical consequences Vconsequences V

It is more easy to produce low mass core It is more easy to produce low mass core collapse SNe, down to ~6 Mcollapse SNe, down to ~6 Mʘ ʘ (electron (electron capture), down to ~8 Mcapture), down to ~8 Mʘ ʘ (normal core (normal core collapse) collapse)

Somewhat in agreement with recent Somewhat in agreement with recent progenitor mass estimations: e.g. Smartt et al. progenitor mass estimations: e.g. Smartt et al. 2008 found a minimum mass at 8.5 ± 1.5 M2008 found a minimum mass at 8.5 ± 1.5 Mʘʘ

Astrophysical Astrophysical Consequences VIConsequences VI

Carbon Burning in massive stars and Carbon Burning in massive stars and SAGB. More extended convective SAGB. More extended convective zones should be favoured by a larger zones should be favoured by a larger 12C+12C rate. 12C+12C rate.

Consequences for the final mass-radius Consequences for the final mass-radius relation, explosion energy release and relation, explosion energy release and related nucleosynthesisrelated nucleosynthesis

M=11.0 M

Z=0.0149

Y=0.2645

The value of Mup

M=8.5 M

Z=0.0149

Y=0.2645

CF88

NEW RATE

‘

SummarySummary

Combining present uncertainties, Combining present uncertainties, MMupup is known no better than is known no better than M=2 M=2 MMʘ ʘ (conservative error estimate).(conservative error estimate).

The (many) The (many) astrophysical/observational astrophysical/observational consequences have been illustrated.consequences have been illustrated.