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Structure and Evolution of Stars Lecture 7 dr dmi r M Potential Energy U(r) (MeV) Coulomb repulsion 1 r Distanc...

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Structure and Evolution of Stars Lecture 7

dr

dmi r

M

Potential Energy U(r) (MeV)

Coulomb repulsion

1 r

Distance (fm)



Potential barrier (a)

Energy

E3,k

E3

(b) E2

Coulomb Proton wave barrier

E3,k

E1

E=0

rn

Energy

Potential energy (Ep)

r

E=0 Nuclear-force well Fig. 2.4: Astrophysics Processes (CUP), ©H Bradt 2008

) dN/dE (MeV

1

dN/dE (MeV

1

)

Energy (keV)

= 17

=4

4

Cowan et al.

1.00

BD+173248 CS 22892!052 CS 31082!001 HD 115444 HD 221170 SS r!process (Simmerer) SS r!process (Arlandini)

Ba

Relative log !

0.60

0.20

Nd

Ce

Dy

Gd

Er

Sm

!0.20

Yb Hf

!0.60 La !1.00

Eu

Ho

Pr Tb

!1.40

55

60

65

Tm 70

Atomic Number

75

Cowan et al. 2011

Figure 1.— Recent abundance determinations in five r-process rich stars, based upon new atomic lab data, compared with two solar system r-process only predictions. The abundances in each star have been normalized to the element Eu. After Sneden et al. (2009). Reproduced by permission of the AAS.