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FIG. 6. The upper panel shows the development of the isotopic abundances of 'H and +He (dotted lines), '7C and '°O (dashed lines), and “N, '80, Ne, and Mg during the hydrogen and helium burning phase burning phase of aM=15 Mo star (see Fig. 1). The lower panel shows the rapid depletion of 4N into '8O and subsequently into 77Ne during the contraction phase of the core of the main sequence star and the ignition of helium burning.

Figure 6 The upper panel shows the development of the isotopic abundances of 'H and +He (dotted lines), '7C and '°O (dashed lines), and “N, '80, Ne, and Mg during the hydrogen and helium burning phase burning phase of aM=15 Mo star (see Fig. 1). The lower panel shows the rapid depletion of 4N into '8O and subsequently into 77Ne during the contraction phase of the core of the main sequence star and the ignition of helium burning.

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*Renormalized; for details see text. >Adopted by NACRE [9]; see text. “See text. “Adopted value (see text). “From [11]. TABLE I. Yield and resonance strength wy of low-energy resonances in '*N(a, y)'*F. The errors of the wy values do not include a common uncertainty of the stopping power (7%).
*Renormalized; for details see text. >Adopted by NACRE [9]; see text. “See text. “Adopted value (see text). “From [11]. TABLE I. Yield and resonance strength wy of low-energy resonances in '*N(a, y)'*F. The errors of the wy values do not include a common uncertainty of the stopping power (7%).
FIG. 1. Temperature (upper panel) and density (lower panel) development for three massive star models, M=13, 15, 20 Mo. The development is calculated from the beginning of the hydrogen burning phase to the end of the helium burning phase. (Courtesy of Alessandro Chieffi.)
FIG. 1. Temperature (upper panel) and density (lower panel) development for three massive star models, M=13, 15, 20 Mo. The development is calculated from the beginning of the hydrogen burning phase to the end of the helium burning phase. (Courtesy of Alessandro Chieffi.)
FIG. 2. The reaction flow during stellar helium burning. The reaction sequence *He(2*He, y)'?C(a, y)!°O is responsible for the energy generation; the reaction sequence IN (a, y) SFC Bt v)8O(a, y)”Ne(a,n) represents the neutron source for the weak s-process component.
FIG. 2. The reaction flow during stellar helium burning. The reaction sequence *He(2*He, y)'?C(a, y)!°O is responsible for the energy generation; the reaction sequence IN (a, y) SFC Bt v)8O(a, y)”Ne(a,n) represents the neutron source for the weak s-process component.
FIG. 3. Yield of the 1042 keV y-ray transition at the 573 keV resonance (left panel) and the yield of the 2523 keV y-ray transition at the 1136 keV resonance (right panel) (for more details see text).
FIG. 3. Yield of the 1042 keV y-ray transition at the 573 keV resonance (left panel) and the yield of the 2523 keV y-ray transition at the 1136 keV resonance (right panel) (for more details see text).
FIG. 4. Decay curves obtained for the two resonances at 573 keV and 1136 keV. The solid lines represent fits to the decay curve (for more details see text).
FIG. 4. Decay curves obtained for the two resonances at 573 keV and 1136 keV. The solid lines represent fits to the decay curve (for more details see text).
TABLE II. Stellar reaction rate for the UN(a, y) '8F reaction. of the 4849 keV state [11]. The excitation function shows a resonance at (577.5+4.5) keV. The error is the sum of the uncertainty due to the step size (+2.5 keV) and the error of the beam energy calibration (+2 keV). This is in very good agreement with the previous result and we adopt a resonance energy of (57343 keV). but only on the well-known decay properties of '8F. At these low @ energies no other reaction channel leading to the for- mation of !8F is open [7,11].
TABLE II. Stellar reaction rate for the UN(a, y) '8F reaction. of the 4849 keV state [11]. The excitation function shows a resonance at (577.5+4.5) keV. The error is the sum of the uncertainty due to the step size (+2.5 keV) and the error of the beam energy calibration (+2 keV). This is in very good agreement with the previous result and we adopt a resonance energy of (57343 keV). but only on the well-known decay properties of '8F. At these low @ energies no other reaction channel leading to the for- mation of !8F is open [7,11].
FIG. 5. The upper panel shows the development of the isotopic abundances of 'H and *+He (dotted lines), 17C and '°O (dashed lines), and 4N, '80, Ne, and *Mg during the hydrogen and helium burning phase of a M=13 Mo star (see Fig. 1). The lower panel shows the rapid depletion of '*N into !8O and subsequently into *’Ne during the contraction phase of the core of the main sequence star and the ignition of helium burning.
FIG. 5. The upper panel shows the development of the isotopic abundances of 'H and *+He (dotted lines), 17C and '°O (dashed lines), and 4N, '80, Ne, and *Mg during the hydrogen and helium burning phase of a M=13 Mo star (see Fig. 1). The lower panel shows the rapid depletion of '*N into !8O and subsequently into *’Ne during the contraction phase of the core of the main sequence star and the ignition of helium burning.
FIG. 7. The upper panel shows the development of the isotopic abundances of 'H and *He (dotted lines), '?C and '°O (dashed lines), and N, '80, “Ne, and Mg during the hydrogen and helium phase of a M=20 Mog star (see Fig. 1). The lower panel shows the rapid depletion of '4N into '8O and subsequently into ?2Ne during the contraction phase of the core of the main sequence star and the ignition of helium burning.
FIG. 7. The upper panel shows the development of the isotopic abundances of 'H and *He (dotted lines), '?C and '°O (dashed lines), and N, '80, “Ne, and Mg during the hydrogen and helium phase of a M=20 Mog star (see Fig. 1). The lower panel shows the rapid depletion of '4N into '8O and subsequently into ?2Ne during the contraction phase of the core of the main sequence star and the ignition of helium burning.
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