The birth environment of the solar system constrained by the relative abundances of the solar radionuclides. (arXiv:1909.06361v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Young_E/0/1/0/all/0/1">Edward Young</a>
The relative abundances of the radionuclides in the solar system at the time
of its birth are crucial arbiters for competing hypotheses regarding the birth
environment of the Sun. The presence of short-lived radionuclides, as evidenced
by their decay products in meteorites, has been used to suggest that
particular, sometimes exotic, stellar sources were proximal to the Sun’s birth
environment. The recent confirmation of neutron star – neutron star (NS-NS)
mergers and associated kilonovae as potentially dominant sources of r-process
nuclides can be tested in the case of the solar birth environment using the
relative abundances of the longer-lived nuclides. Critical analysis of the 15
radionuclides and their stable partners for which abundances and production
ratios are well known suggests that the Sun formed in a typical massive
star-forming region (SFR). The apparent overabundances of short-lived
radionuclides (e.g., $^{26} {rm Al}$, $^{41}{rm Ca}$, $^{36}{rm Cl}$) in
the early solar system appears to be an artifact of a heretofore
under-appreciation for the important influences of enrichment by Wolf-Rayet
winds in SFRs. The long-lived nuclides (e.g., $^{238}{rm U}$, $^{244}{rm
Pu}$, $^{247}{rm Cr}$, $^{129}{rm I}$) are consistent with an average time
interval between production events of $10^8$ years, seemingly too short to be
the products of NS-NS mergers alone. The relative abundances of all of these
nuclides can be explained by their mean decay lifetimes and an average
residence time in the ISM of $sim200$ Myr. This residence time evidenced by
the radionuclides is consistent with the average lifetime of dust in the ISM
and the timescale for converting molecular cloud mass to stars.
The relative abundances of the radionuclides in the solar system at the time
of its birth are crucial arbiters for competing hypotheses regarding the birth
environment of the Sun. The presence of short-lived radionuclides, as evidenced
by their decay products in meteorites, has been used to suggest that
particular, sometimes exotic, stellar sources were proximal to the Sun’s birth
environment. The recent confirmation of neutron star – neutron star (NS-NS)
mergers and associated kilonovae as potentially dominant sources of r-process
nuclides can be tested in the case of the solar birth environment using the
relative abundances of the longer-lived nuclides. Critical analysis of the 15
radionuclides and their stable partners for which abundances and production
ratios are well known suggests that the Sun formed in a typical massive
star-forming region (SFR). The apparent overabundances of short-lived
radionuclides (e.g., $^{26} {rm Al}$, $^{41}{rm Ca}$, $^{36}{rm Cl}$) in
the early solar system appears to be an artifact of a heretofore
under-appreciation for the important influences of enrichment by Wolf-Rayet
winds in SFRs. The long-lived nuclides (e.g., $^{238}{rm U}$, $^{244}{rm
Pu}$, $^{247}{rm Cr}$, $^{129}{rm I}$) are consistent with an average time
interval between production events of $10^8$ years, seemingly too short to be
the products of NS-NS mergers alone. The relative abundances of all of these
nuclides can be explained by their mean decay lifetimes and an average
residence time in the ISM of $sim200$ Myr. This residence time evidenced by
the radionuclides is consistent with the average lifetime of dust in the ISM
and the timescale for converting molecular cloud mass to stars.
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