| GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS |
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Mass Fraction of 13C-Pocket in Metal-Poor AGB Stars and the Primary Nature of Neutron Source |
| CUI Dong-Nuan, GENG Yuan-Yuan, CUI Wen-Yuan, ZHANG Bo |
| Department of Physics, Hebei Normal University, Shijiazhuang 050016Hebei Advanced Thin Films Laboratory, Shijiazhuang 050016 |
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| Cite this article: |
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CUI Dong-Nuan, GENG Yuan-Yuan, CUI Wen-Yuan et al 2009 Chin. Phys. Lett. 26 039701 |
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Abstract Chemical abundances of very metal-poor s-rich stars contain excellent information to set new constraints on models of neutron-capture processes at low metallicity. Using the parametric approach based on the radiative s-process nucleosynthesis model, we obtain the mass fraction q of 13C-pocket, the overlap factor r, the neutron exposure per interpulse Δτ, and the component coefficients of the s-process and the r-process for 25 s-rich stars, respectively. We find that q deduced for the lead stars is comparable to the overlap factor r, which is larger than the standard case (hereafter ST case) of the AGB model (q~0.05) about 10 times, and Δτ are about 10 times smaller than the ST case (Δτ=7.0mbarn-1). Although the two parameters obtained for the lead stars are very different from the ST case of the AGB stellar model, it is worth noting that the total amounts of 13C in metal-poor condition are close to the ST case. The above relation is a significant evidence for the primary nature of the neutron source and the lead stars could be polluted by low-mass AGB stars. Because interpulse period declines with increasing stellar mass, for high-mass AGB star, the neutron irradiation may be terminated due to their shorter interpulse period. Thus the neutron exposure per interpulse of the larger AGB stars should be about 10 times smaller than the ST case. In this case, the primary nature of the neutron source also exists.
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| Keywords:
97.10.Cv
26.45.+h
97.10.Tk
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Received: 25 June 2008
Published: 19 February 2009
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| PACS: |
97.10.Cv
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(Stellar structure, interiors, evolution, nucleosynthesis, ages)
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26.45.+h
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97.10.Tk
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(Abundances, chemical composition)
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[1] Busso M, Gallino R and Wasserburg G J 1999 Ann.Rev. Astron. Astrophys. 37 239
[2] Gallino R, Arlandini C, Busso M, Lugaro M, Travaglio C,Straniero O, Chieffi A and Limongi M 1998 Astrophys. J. 497 388
[3] Goriely S and Mowlavi N 2000 Astron. Astrophys. 362 599
[4] Van Eck S, Goriely S, Jorissen A and Plez B 2001 Nature 412 793
[5] Aoki W, Ryan S G, Norris J E, Beers T C, Ando H, IwamotoN, Kajino T, Mathews G J and Fujimoto M Y 2001 Astrophys. J. 561 346
[6] Aoki W, Ryan S G, Norris J E, Beers T C, Ando H andTsangarides S 2002 Astrophys. J. 580 1149
[7] Cohen J G, Christlieb N, Qian Y Z and Wasserburg G J 2003 Astrophys. J. 588 1082
[8] Lucatello S, Gratton R, Cohen J G, Beers T C, ChristliebN, Carretta E and Ramrez S 2003 Astron. J. 125 875
[9] Van Eck S, Goriely S, Jorissen A and Plez B 2003 Astron. Astrophys. 404 291
[10] Johnson J A and Bolte M 2002 Astrophys. J. 579 L87
[11] Johnson J A and Bolte M 2004 Astrophys. J. 605 462
[12] Straniero O, Gallino R and Cristallo S 2006 Nucl.Phys. A 777 311
[13] Bona\v{ci\'{c Marinovi\'{c A, Izzard R G, Lugaro Mand Pols O R 2006 Mem. S. A. It. 77 879
[14] Reyniers M, Van Winckel H, Gallino R and Straniero O 2004 Astron. Astrophys. 417 269
[15] Cui W Y and Zhang B 2006 Mon. Not. R. Astron. Soc. 368 305
[16] Zhang B, Ma K and Zhou G D 2006 Astrophys. J. 642 1075
[17] Ma K, Cui W Y and Zhang B 2007 Mon. Not. R. Astron.Soc. 375 1418
[18] Bao Z Y, Beer H, K\"{appeler F, Voss F, and Wisshak K2000 Atomic Data and Nuclear Data Tables 76 70
[19] Cui W Y, Zhang B, Ma K and Zhang L 2007 Astrophys.J. 657 1037
[20] Arlandini C, K\"{appeler F, Wisshak K, Gallino R, LugaroM, Busso M and Straniero O 1999 Astrophys. J. 525 886
[21] Ivans I I, Sneden C, Gallino R, Cowan J J and Preston GW, 2005 Astrophys. J. 627 145
[22] Cohen J G, McWilliam A, Shectman S, Thompson I,Christlieb N, Melendez J, Ramirez S, Swensson A and Zickgraf F J2006 Astron. J. 132 137
[23] Masseron T, Van Eck S, Famaey B, Goriely S, Plez B, SiessL, Beers T C, Primas F and Jorissen A 2006 Astron. Astrophys. 455 1059
[24] Barbuy B, Spite M, Spite F, Hill V, Cayrel R, Plez B andPetitjean P 2005 Astron. Astrophys. 429 1031
[25] Jonsell K, Barklem P S, Gustafsson B, Christlieb N, HillV, Beers T C and Holmberg J 2006 Astron. Astrophys. 451651
[26] Aruna Goswami, Aoki W, Beers T C, Christlieb N, Norris JE, Ryan S G and Tsangarides S 2006 Mon. Not. R. Astron. Soc. 372 343
[27] Karakas A I and Lattanzio J 2003 Planetary Nebulae:Their Evolution and Role in the Universe (Canberra, Australia19--23 November 2001) 209 82
[28] Herwig F 2000 Astron. Astrophys. 360 952
[29] Busso M, Gallino R, Lambert D L, Travaglio C and Smith VV 2001 Astrophys. J. 557 802
[30] Zhang F H, Zhou G D and Zhang B 2008 Chin. Astron.Astrophys. 32 369
[31] Iben I Jr 1977 Astrophys. J. 217 788
[32] Zijlstra A A 2004 Mon. Not. R. Astron. Soc. 348 L23
[33] Suda T, Aikawa M, Machida M N, Fujimoto M Y, Iben I Jr2004 Astrophys. J. 611 476 |
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