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Carbon and nitrogen isotopic ratios in supernova models of low metallicity stars and presolar grains from supernovae
ELSEVIER
Nuclear
Physics
A718
(2003)
469~471~ www.elsevier.com/locate/npe
Carbon and Nitrogen Isotopic Metallicity Stars and Presolar T. Yoshidaa “Department
Ratios in Supernova Models Grains from Supernovae
of Low
and M. Hashimotoa of Physics,
Kyushu
University,
Ropponmatsu,
F’ukuoka
810-8560,
Japan
We investigate the possible range of the isotopic ratios of carbon and nitrogen in the mixture of different layers of supernovae with 2 = 2, and 2 = 0.12,. We carry out the postprocessing nucleosynthesis calculations using the evolution profile of 4 IV& He stars and that of the following supernova explosions to obtain abundance distributions. Main difference due to the metallicity is found in the range of the isotopic ratios of the mixture between the He/C-layer and the He/N-layer. Most of the isotopic ratios of Sic type X grains are inside the range of the isotopic ratios of the mixture between the He/C-layer and the He/N- or Si/S-layer of the supernova models.
1. INTRODUCTION SIC type X grains [l-3], low density graphite grains [4,5], and some S&N4 grains [6] have been identified as supernova origin. These grains are identified mainly on the basis of the excesses of ‘%Si, carbon isotopic ratio, and traces of the radioactive nuclei, 44Ti. Quantitative comparison between isotopic ratios of presolar grains from supernovae and those evaluated from supernova models in [7] has been carried out for SIC type X grains [3] and for low density graphite grains [5]. However, all isotopic ratios of the presolar grains have not been reproduced. One combination of the isotopic ratios, i.e., the number ratios of isotopes, which has not been reproduced is 12C/13C and r4N/15N. The ratio of 14N/15N obtained from the supernova model has been larger than that of the presolar grains with a given 12C/13C. We investigate the range of 12C/13C and 14N/15N ratios in the supernova models obtained from the solar metallicity (2 = 2,) and the low metallicity (Z= 0.1 Z,) stars and compare with those of the presolar grains. This is because the metallicity of the material of the solar system is originating from stars of which metallicity would be lower than the solar one. We evaluate the abundance distributions by postprocessing nucleosynthesis calculation of 4 &Ia He stars corresponding to 15 A4@ ZAMS stars. Then, we evaluate the range of 12C/13C and 14N/15N ratios of the mixture between arbitrary two mass coordinates with the condition of C/O> 1 and discuss the difference due to the metallicities.
2. MODELS We calculate the evolution of 4 IL& He stars with 2 = 2, and Z = O.lZ, from the ignition of the He burning to the beginrung of the core collapse using a He star evolution I 0375-9474/03/$
- see front
doi:lO.l016/S0375-9474(03)00854-6
matter
0 2003 Published
by Elsevier
Science
B.V.
47oc
7: Yoshida. M. Hashimoto/Nuclear
Physics A718 (2003) 469c-471~
is adopted from CFHZ85 [IO]. code [8,9]. In this model, the reaction rate of ~‘C((Y, y)“O The initial chemical composition is assumed to be (X(“He), X(14N))=(0.9878, 0.0122) and (0.99878,0.00122) f or 2 = ZcIJ star and 2 = O.lZo star. respectively. After the ronstruct,ion of the prcsupernova. models. we carry out the supernova. explosion calculation. We use the explosion model in [ll]. The explosion energy and the location of the mass cut are commonly set to be 1 x lO”l ergs and 1.41 nil,, respectively. Using the t,empera,ture, density, and radius profiles during the stellar evolution and the supernova explosion of t,he 4 nZD He stars wit,h 2 = 2, and 2 = O.lZ,, we perform the postprocessing nucleosynthesis calculations to obtain the abundance distributions in the supernovae. The nuclear reaction network for the post,processing nucleosynthesis consists of 515 species up to Zr.
3. RESULTS
AND
DISCUSSION
The number ratios, of 12C/13C and 14N/15N at each mass coordinate and the range of those by the mixture between arbitrary two mass coordinates with the condition of C/O> 1 in all layers are shown in Figure 1. Most of the isotopic ratios of SIC type X grains are inside the range evaluated from the supernova models with both cases of the metallicities: the characteristics of Sic type X grains, i.e., 12C/‘3C>(12C/‘3C)o and 14N/‘5N<(‘4N/‘5N)o, is reproduced by the mixing bet,ween the outer He/C-layer and the He/N- or inner Si/S-layer for the solar metallicity model and between the He/C-layer and the %/S-layer for the low metallicity model. However, the ratios of low density graphite grains with 1*C/‘3C<(12C/‘3C)o are out of the range. Main difference between the solar met,allicity model and the low metallicity model is the range of the isotopic ratios of the mixture between the outer He/C-layer and t,he He/N-layer. With a given “C/13C ratio, the mixture of the low metallicity model model. When provides 14N / 15N ratio much larger than that, of the solar metallicity 14N/15N<(‘4N/‘5N),, the minimum ratio of 1*C/‘3C is about 100 for t,he solar metallicity model and about 3000 for the low metallicity model. This is because the mass fraction of 13C in the inner region of the He/C-layer of the solar metallicity model is two orders of magnitude smaller t,han that of the low mctallicity model. In the former case the 12C/‘3C ratio of the mixture with a fraction of the He/N-layer such that 14N/15N (14N/l”N),, becomes much smaller than 12C/13C ratio in the He/C-layer. In the latter case the 12C/13C ratio of the corresponding mixture with the fraction of the He/N-layer is close to t,hat of t,he He/C-layer. In the mixture of inner layers such as the Si/S- and Ni-layers and the He/C-layer, the is roughly independent of the metallicitjy. Further, the range of 12C/‘“C and ‘“N/‘“.Y mixing between the Si/S-layer a.nd the He/C-layer provide small 12C/13C and 14N/l”N ratios which rcproducc the ratios of Sic type X grains. In order to reproduce small 12C/13C and 14N/15N rat,ios shown in low densitv graphite grains ard a part of Sic type X grains: WC should consider the mixing not only between two layers but also of t,hrer or more layers [3.5]. We note that, the Ni-layer provides small ‘“C/‘“C and 14N/‘5K ratios and tlit radioactive riucl(~i. ““Ti 111multi-layer mixing of not only out,er Hc-ric+ layers but also inner lwy~rs such its Si/S- anti Si-layclrs wol11d l)c important, to rcprotliice tlic isotopic, ratios of presolar grains from supcrnovii(‘.
7: Yoshida. M. Hashimoto/Nuclear
10-2 IO0
Physics A718 (2003) 469c-47/c
47lc
-I 102
IO4
IO6
n(“c) / n(‘“c)
IO0
IO2
IO4
IO6
n(“c) / n(‘“c)
Figure 1. The number ratios of 12C/13C and 14N/‘“N in the supernovae evolved from 4 Ma He star with 2 = 2, (panel (a)) and 2 = 0.12, (panel (b)). Open circles denote the isotopic ratios at each mass coordinate of the supernova models. The region enclosed by the solid line is the range of the mixture between arbitrary two mass coordinates with the condition of C/O>l. The region enclosed by the dashed line is the range of the mixture in the He/C- and He/N-layers. Closed circles with error bars denote the ratios of Sic type X grains in [l&3] and Si3Nd grains in [6] and diamonds with error bars denote the ratios of low density graphit,e grains tabulated in [5].
This study is supported by Research Fellowships of Science for Young Scientists (No. 12000289).
of the Japan Society
for the Promotion
REFERENCES 1. 2.
S. Amari, P. Hoppe, E. Zinner, and R. S. Lewis, Astrophys. J. 394 (1992) L-23. L. R. Nittler, S. Amari, E. Zinner. S. E. Woosley, and R. S. Lewis, Astrophys. J. 462 (1996) L31. 3. P. Hoppe, R. Strebel. P. Eberhardt, S. Amari, and R. S. Lewis, Meteoritics & Planet. Sci. 35 (2000) 1157. 4. S. Amari, E. Zinner, and R. S. Lewis, Astrophys. J. 470 (1996) LlOl. 5. C. Travaglio, R. Gallino. S. Amari. E. Zinner, S. E. Woosley, and R. S. Lewis, Astrophys. J. 510 (1999) 325. 6. L. R. Nittler, P. Hoppe. C. M. 0. ‘D. Alexander, S. Amari. I’. Eberhardt, X. Gao. R. S. Lewis, R. Strebel, R. M. Walker. and E. Zinrler, Ast,rophys. J. 453 (1995) L25. 7. S. E. Woosley and T. A. Weaver. Astrophys. .J. Suppl. 101 (1995) 1X1. 8. K. Nomoto and nl. Hashimoto. Phvs. Rep. I63 (1988) 13. 9. M. Hashirnoto. Prog. Theor. Phys. 94 (1995) 663. 10. G. R. Caughlan. W. A. Fowler, M. J. Harris: B. A. Zimmcrma.n, Atomic D&a K11cl. Data Tables 32 (1985) 197. 11. T. Shigcyama, K. Nomoto, II. Hashimot,o, and D. Sugimot,o, Nature 328 (1987) 320.
Nuclear
Physics
A718
(2003)
469~471~ www.elsevier.com/locate/npe
Carbon and Nitrogen Isotopic Metallicity Stars and Presolar T. Yoshidaa “Department
Ratios in Supernova Models Grains from Supernovae
of Low
and M. Hashimotoa of Physics,
Kyushu
University,
Ropponmatsu,
F’ukuoka
810-8560,
Japan
We investigate the possible range of the isotopic ratios of carbon and nitrogen in the mixture of different layers of supernovae with 2 = 2, and 2 = 0.12,. We carry out the postprocessing nucleosynthesis calculations using the evolution profile of 4 IV& He stars and that of the following supernova explosions to obtain abundance distributions. Main difference due to the metallicity is found in the range of the isotopic ratios of the mixture between the He/C-layer and the He/N-layer. Most of the isotopic ratios of Sic type X grains are inside the range of the isotopic ratios of the mixture between the He/C-layer and the He/N- or Si/S-layer of the supernova models.
1. INTRODUCTION SIC type X grains [l-3], low density graphite grains [4,5], and some S&N4 grains [6] have been identified as supernova origin. These grains are identified mainly on the basis of the excesses of ‘%Si, carbon isotopic ratio, and traces of the radioactive nuclei, 44Ti. Quantitative comparison between isotopic ratios of presolar grains from supernovae and those evaluated from supernova models in [7] has been carried out for SIC type X grains [3] and for low density graphite grains [5]. However, all isotopic ratios of the presolar grains have not been reproduced. One combination of the isotopic ratios, i.e., the number ratios of isotopes, which has not been reproduced is 12C/13C and r4N/15N. The ratio of 14N/15N obtained from the supernova model has been larger than that of the presolar grains with a given 12C/13C. We investigate the range of 12C/13C and 14N/15N ratios in the supernova models obtained from the solar metallicity (2 = 2,) and the low metallicity (Z= 0.1 Z,) stars and compare with those of the presolar grains. This is because the metallicity of the material of the solar system is originating from stars of which metallicity would be lower than the solar one. We evaluate the abundance distributions by postprocessing nucleosynthesis calculation of 4 &Ia He stars corresponding to 15 A4@ ZAMS stars. Then, we evaluate the range of 12C/13C and 14N/15N ratios of the mixture between arbitrary two mass coordinates with the condition of C/O> 1 and discuss the difference due to the metallicities.
2. MODELS We calculate the evolution of 4 IL& He stars with 2 = 2, and Z = O.lZ, from the ignition of the He burning to the beginrung of the core collapse using a He star evolution I 0375-9474/03/$
- see front
doi:lO.l016/S0375-9474(03)00854-6
matter
0 2003 Published
by Elsevier
Science
B.V.
47oc
7: Yoshida. M. Hashimoto/Nuclear
Physics A718 (2003) 469c-471~
is adopted from CFHZ85 [IO]. code [8,9]. In this model, the reaction rate of ~‘C((Y, y)“O The initial chemical composition is assumed to be (X(“He), X(14N))=(0.9878, 0.0122) and (0.99878,0.00122) f or 2 = ZcIJ star and 2 = O.lZo star. respectively. After the ronstruct,ion of the prcsupernova. models. we carry out the supernova. explosion calculation. We use the explosion model in [ll]. The explosion energy and the location of the mass cut are commonly set to be 1 x lO”l ergs and 1.41 nil,, respectively. Using the t,empera,ture, density, and radius profiles during the stellar evolution and the supernova explosion of t,he 4 nZD He stars wit,h 2 = 2, and 2 = O.lZ,, we perform the postprocessing nucleosynthesis calculations to obtain the abundance distributions in the supernovae. The nuclear reaction network for the post,processing nucleosynthesis consists of 515 species up to Zr.
3. RESULTS
AND
DISCUSSION
The number ratios, of 12C/13C and 14N/15N at each mass coordinate and the range of those by the mixture between arbitrary two mass coordinates with the condition of C/O> 1 in all layers are shown in Figure 1. Most of the isotopic ratios of SIC type X grains are inside the range evaluated from the supernova models with both cases of the metallicities: the characteristics of Sic type X grains, i.e., 12C/‘3C>(12C/‘3C)o and 14N/‘5N<(‘4N/‘5N)o, is reproduced by the mixing bet,ween the outer He/C-layer and the He/N- or inner Si/S-layer for the solar metallicity model and between the He/C-layer and the %/S-layer for the low metallicity model. However, the ratios of low density graphite grains with 1*C/‘3C<(12C/‘3C)o are out of the range. Main difference between the solar met,allicity model and the low metallicity model is the range of the isotopic ratios of the mixture between the outer He/C-layer and t,he He/N-layer. With a given “C/13C ratio, the mixture of the low metallicity model model. When provides 14N / 15N ratio much larger than that, of the solar metallicity 14N/15N<(‘4N/‘5N),, the minimum ratio of 1*C/‘3C is about 100 for t,he solar metallicity model and about 3000 for the low metallicity model. This is because the mass fraction of 13C in the inner region of the He/C-layer of the solar metallicity model is two orders of magnitude smaller t,han that of the low mctallicity model. In the former case the 12C/‘3C ratio of the mixture with a fraction of the He/N-layer such that 14N/15N (14N/l”N),, becomes much smaller than 12C/13C ratio in the He/C-layer. In the latter case the 12C/13C ratio of the corresponding mixture with the fraction of the He/N-layer is close to t,hat of t,he He/C-layer. In the mixture of inner layers such as the Si/S- and Ni-layers and the He/C-layer, the is roughly independent of the metallicitjy. Further, the range of 12C/‘“C and ‘“N/‘“.Y mixing between the Si/S-layer a.nd the He/C-layer provide small 12C/13C and 14N/l”N ratios which rcproducc the ratios of Sic type X grains. In order to reproduce small 12C/13C and 14N/15N rat,ios shown in low densitv graphite grains ard a part of Sic type X grains: WC should consider the mixing not only between two layers but also of t,hrer or more layers [3.5]. We note that, the Ni-layer provides small ‘“C/‘“C and 14N/‘5K ratios and tlit radioactive riucl(~i. ““Ti 111multi-layer mixing of not only out,er Hc-ric+ layers but also inner lwy~rs such its Si/S- anti Si-layclrs wol11d l)c important, to rcprotliice tlic isotopic, ratios of presolar grains from supcrnovii(‘.
7: Yoshida. M. Hashimoto/Nuclear
10-2 IO0
Physics A718 (2003) 469c-47/c
47lc
-I 102
IO4
IO6
n(“c) / n(‘“c)
IO0
IO2
IO4
IO6
n(“c) / n(‘“c)
Figure 1. The number ratios of 12C/13C and 14N/‘“N in the supernovae evolved from 4 Ma He star with 2 = 2, (panel (a)) and 2 = 0.12, (panel (b)). Open circles denote the isotopic ratios at each mass coordinate of the supernova models. The region enclosed by the solid line is the range of the mixture between arbitrary two mass coordinates with the condition of C/O>l. The region enclosed by the dashed line is the range of the mixture in the He/C- and He/N-layers. Closed circles with error bars denote the ratios of Sic type X grains in [l&3] and Si3Nd grains in [6] and diamonds with error bars denote the ratios of low density graphit,e grains tabulated in [5].
This study is supported by Research Fellowships of Science for Young Scientists (No. 12000289).
of the Japan Society
for the Promotion
REFERENCES 1. 2.
S. Amari, P. Hoppe, E. Zinner, and R. S. Lewis, Astrophys. J. 394 (1992) L-23. L. R. Nittler, S. Amari, E. Zinner. S. E. Woosley, and R. S. Lewis, Astrophys. J. 462 (1996) L31. 3. P. Hoppe, R. Strebel. P. Eberhardt, S. Amari, and R. S. Lewis, Meteoritics & Planet. Sci. 35 (2000) 1157. 4. S. Amari, E. Zinner, and R. S. Lewis, Astrophys. J. 470 (1996) LlOl. 5. C. Travaglio, R. Gallino. S. Amari. E. Zinner, S. E. Woosley, and R. S. Lewis, Astrophys. J. 510 (1999) 325. 6. L. R. Nittler, P. Hoppe. C. M. 0. ‘D. Alexander, S. Amari. I’. Eberhardt, X. Gao. R. S. Lewis, R. Strebel, R. M. Walker. and E. Zinrler, Ast,rophys. J. 453 (1995) L25. 7. S. E. Woosley and T. A. Weaver. Astrophys. .J. Suppl. 101 (1995) 1X1. 8. K. Nomoto and nl. Hashimoto. Phvs. Rep. I63 (1988) 13. 9. M. Hashirnoto. Prog. Theor. Phys. 94 (1995) 663. 10. G. R. Caughlan. W. A. Fowler, M. J. Harris: B. A. Zimmcrma.n, Atomic D&a K11cl. Data Tables 32 (1985) 197. 11. T. Shigcyama, K. Nomoto, II. Hashimot,o, and D. Sugimot,o, Nature 328 (1987) 320.