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Diverse supernova sources for the r-process

Qian, Y.-Z. and Vogel, P. and Wasserburg, G. J. (1998) Diverse supernova sources for the r-process. Astrophysical Journal, 494 (1). pp. 285-296. ISSN 0004-637X. doi:10.1086/305198.

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We present a simplified analysis using equations for the charge flow, which include ν_e capture, for the production of r-process nuclei in the context of the recent supernova hot bubble model. The role of ν_e capture in speeding up the charge flow, particularly at the closed neutron shells, is studied together with the β flow at freezeout and the effect of neutrino-induced neutron emission on the abundance pattern after freezeout. It is shown that a semiquantitative agreement with the gross solar r-process abundance pattern from the peak at mass number A ~ 130 through the peak at A ~ 195 and up to the region of the actinides can be obtained by a superposition of two distinctive kinds of r-process events. These correspond to a low frequency case L and a high frequency case H, which take into account the low abundance of ^(129)I and the high abundance of ^(182)Hf in the early solar nebula. The lifetime of ^(182)Hf (τ_(182) ≈ 1.3 × 10^7 yr) associates the events in case H with the most common Type II supernovae. These events would be mainly responsible for the r-process nuclei near and above A ~ 195. They would also make a significant amount of the nuclei between A ~ 130 and 195, including ^(182)Hf, but would make very little ^(129)I. In order to match the solar r-process abundance pattern and to satisfy the ^(129)I and ^(182)Hf constraints, the events in case L, which would make the r-process nuclei near A ~ 130 and the bulk of those between A ~ 130 and 195, must occur ~10 times less frequently but eject ~10-20 times more r-process material in each event. Assuming that all of the supernovae producing r-process nuclei represent a similar overall process, we speculate that the usual neutron star remnants, and hence prolonged ejection of r-process material, are associated with the events in case L. We further speculate that the more frequently occurring events in case H have ejection of other r-process material terminated by black hole formation during the neutrino cooling phase of the protoneutron star. This suggests that there is now an inventory of ~5 × 10^8 black holes with masses ~1 M_☉ and ~5 × 10^7 neutron stars resulting from supernovae in the Galaxy. This r-process model would have little effect on the estimates of the supernova contributions to the non-r-process nuclei.

Item Type:Article
Related URLs:
URLURL TypeDescription
Vogel, P.0000-0003-0587-5466
Wasserburg, G. J.0000-0002-7957-8029
Additional Information:© 1998 The American Astronomical Society. Received 1997 June 9. Accepted 1997 September 15. We want to thank Gerry Brown and Sterl Phinney for valuable discussions. We also want to thank the referee, Al Cameron, for helpful comments. This work was supported in part by the US Department of Energy under Grant No. DE-FG03-88ER-40397, by NASA under Grant No. NAG 5-4076, and by Division Contribution No. 5827(973). Y.-Z. Qian was supported by the David W. Morrisroe Fellowship at Caltech.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG03-88ER-40397
David W. Morrisroe FellowshipUNSPECIFIED
Subject Keywords:elementary particles; nuclear reactions, nucleosynthesis, abundances; supernovae: general
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Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences5827
Lunatic Asylum Lab973
Issue or Number:1
Record Number:CaltechAUTHORS:20131119-104855886
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Official Citation:Qian, YZ; Vogel, P; Wasserburg, GJ. ASTROPHYSICAL JOURNAL Volume: 494 Issue: 1 Pages: 285-296.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42564
Deposited By: Kristofer Jolley
Deposited On:19 Nov 2013 22:52
Last Modified:10 Nov 2021 16:25

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