We consider the short-lived radionuclide (SLR) 36Cl in calcium-aluminum-rich inclusions (CAIs) found in primitive meteorites with the solar wind implantation model. In this model, SLRs are produced via nuclear reaction with solar energetic particles (SEPs) interacting with gaseous targets in the protosolar atmosphere in T-Tauri stars. These SLRs are captured by the solar wind and then implanted in CAI precursor materials, which have dropped from the funnel flow leading onto the protostar. This method of incorporating SLRs into solar system materials is currently active in our solar system and has been measured with SLRs from the solar wind being implanted on the lunar surface. T-Tauri stars are capable of SEP fluxes ~105 greater than contemporary SEP fluxes. Here we scale the production rate of 36Cl to the ancient SEP activity. From the enhanced production rates and the refractory mass inflow rate at 0.06？AU from the protosun, we model the ancient 36Cl content in CAIs. We find the initial isotopic ratio of 36Cl/35Cl to range from about 1 × 10？5 to 5 × 10？5 and the concentration of 36Cl to range from about 3 × 1013 to 1.5 × 1014 atoms g？1. 1. Introduction Studies report evidence for the incorporation of the short-lived radionuclide (SLR) (T1/2 = 0.3？Myr) 36Cl into early solar system materials, including calcium-aluminum-rich inclusions (CAIs). Lin et al. [1] infer an initial 36Cl/35Cl ratio of ≥ in sodalite from the carbonaceous chondrite Ningqiang based on Al-Mg systematics. Also, relying upon Al-Mg systematics, Jacobsen et al. [2] report that initial ratio of 36Cl/35Cl in wadalite from Allende would have been > had the initial 26Al/27Al ratio been the canonical value of ~ . Clues to the source of the 36Cl can be gleaned from this initial ratio. If the initial 36Cl/35Cl had been ~ , the source of 36Cl most likely would not have been from a nearby super nova or AGB star [3]. A remaining mechanism for the production of this radionuclide is local irradiation from solar energeticparticle (SEP) born in the protosolar atmosphere. The initial SLR ratios can be used to constrain early solar system evolution and conditions. This is especially true in terms of solar luminosity and flaring characterization. Bricker and Caffee [4] proposed a solar wind implantation model for incorporation of 10Be in CAI precursor materials. In this model, 10Be and possibly other SLRs are produced by SEP reactions in the protosolar atmosphere of a more energetic T-Tauri sun, characterized by SEP fluxes many orders of magnitude greater than contemporary particle fluxes. Studies of
References
[1]
Y. Lin, Y. Guan, L. A. Leshin, Z. Ouyang, and D. Wang, “Short-lived chlorine-36 in a Ca- and Al-rich inclusion from the Ningqiang carbonaceous chondrite,” Proceedings of the National Academy of Sciences of the United States of America, vol. 102, no. 5, pp. 1306–1311, 2005.
[2]
B. Jacobsen, J. Matzel, I. D. Hutcheon et al., “Formation of the short-lived radionuclide 36Cl in the protoplanetary disk during late-stage irradiation of a volatile-rich reservoir,” Astrophysical Journal Letters, vol. 731, no. 2, pp. L28–L34, 2011.
[3]
G. J. Wasserburg, M. Busso, R. Gallino, and K. M. Nollett, “Short-lived nuclei in the early solar system: possible AGB sources,” Nuclear Physics A, vol. 777, pp. 5–69, 2006.
[4]
G. E. Bricker and M. W. Caffee, “Solar wind implantation model for 10Be in calcium-aluminum inclusions,” Astrophysical Journal, vol. 725, no. 1, pp. 443–449, 2010.
[5]
E. D. Feigelson, G. P. Garmtextre, and S. H. Pravdo, “Magnetic flaring in the pre-main-sequence sun and implications for the early solar system,” Astrophysical Journal Letters, vol. 572, no. 1, pp. 335–349, 2002.
[6]
K. Nishiizumtext and M. W. Caffee, “Beryllium-10 from the sun,” Science, vol. 294, no. 5541, pp. 352–354, 2001.
[7]
A. J. T. Jull, D. Lal, L. R. McHargue, G. S. Burr, and D. J. Donahue, “Cosmogenic and implanted radionuclides studied by selective etching of lunar soils,” Nuclear Instruments & Methods in Physics Research B, vol. 172, no. 1–4, pp. 867–872, 2000.
[8]
I. Leya, A. N. Halliday, and R. Wieler, “The predictable collateral consequences of nucleosynthesis by spallation reactions in the early solar system,” Astrophysical Journal Letters, vol. 594, no. 1, pp. 605–616, 2003.
[9]
F. H. Shu, H. Shang, and T. Lee, “Toward an astrophysical theory of chondrites,” Science, vol. 271, no. 5255, pp. 1545–1552, 1996.
[10]
F. H. Shu, H. Shang, A. E. Glassgold, and T. Lee, “X-rays and fluctuating x-winds from protostars,” Science, vol. 277, no. 5331, pp. 1475–1479, 1997.
[11]
F. H. Shu, H. Shang, M. Gounelle, A. E. Glassgold, and T. Lee, “The origin of chondrules and refractory inclusions in chondritic meteorites,” Astrophysical Journal Letters, vol. 548, no. 2, pp. 1029–1050, 2001.
[12]
T. Lee, F. H. Shu, H. Shang, A. E. Glassgold, and K. E. Rehm, “Protostellar cosmtextc rays and extinct radioactivities in meteorites,” Astrophysical Journal Letters, vol. 506, no. 2, pp. 898–912, 1998.
[13]
N. Calvet, C. Brice？o, J. Hernández et al., “Disk evolution in the orion OBI association,” Astronomtextcal Journal, vol. 129, no. 2, pp. 935–946, 2005.
[14]
D. Ward-Thompson, “The formation and evolution of low mass protostars,” Astrophysics & Space Science, vol. 239, no. 1, pp. 151–170, 1996.
[15]
R. C. Reedy and K. Marti, “Solar-cosmtextc-ray fluxes during the last 10 mtextllion years,” in The Sun in Time, C. P. Sonnet, M. S. Giampapa, and M. S. Mathews, Eds., pp. 260–287, University of Arizona Press, Tucson, Ariz, USA, 1991.
[16]
K. Lodders, “Solar system abundances and condensation temperatures of the elements,” Astrophysical Journal Letters, vol. 591, no. 2, pp. 1220–1247, 2003.
[17]
M. Gounelle, F. H. Shu, H. Shang, A. E. Glassgold, K. E. Rehm, and T. Lee, “The irradiation origin of beryllium radioisotopes and other short-lived radionuclides,” Astrophysical Journal Letters, vol. 640, no. 2, pp. 1163–1170, 2006.
[18]
G. F. Herzog, M. W. Caffee, T. Faestermann et al., “Cross sections from 5 to 35？MeV for the reactions (3He,x)26Al, 27Al(3He,x)26Al, (3He,x)41Ca, and (3He,x)36Cl: implications for early irradiation in the solar system,” Meteoritics and Planetary Science, vol. 46, no. 10, pp. 1427–1446, 2011.
[19]
K. K. Marhas and J. N. Goswami, “Low energy particle production of short-lived nuclides in the early solar system,” New Astronomy Reviews, vol. 48, no. 1–4, pp. 139–144, 2004.
