SIMBAD references

2019ApJ...882...40J - Astrophys. J., 882, 40-40 (2019/September-1)

The lanthanide fraction distribution in metal-poor stars: a test of neutron star mergers as the dominant r-process site.


Abstract (from CDS):

Multimessenger observations of the neutron star merger GW170817 and its kilonova proved that neutron star mergers can synthesize large quantities of r-process elements. If neutron star mergers in fact dominate all r-process element production, then the distribution of kilonova ejecta compositions should match the distribution of r-process abundance patterns observed in stars. The lanthanide fraction (XLa) is a measurable quantity in both kilonovae and metal-poor stars, but it has not previously been explicitly calculated for stars. Here we compute the lanthanide fraction distribution of metal-poor stars ([Fe/H] < - 2.5) to enable comparison to current and future kilonovae. The full distribution peaks at log XLa ∼ -1.8, but r-process-enhanced stars ([Eu/Fe] > 0.7) have distinctly higher lanthanide fractions: logXLa≳-1.5. We review observations of GW170817 and find general consensus that the total logXLa=-2.2±0.5, somewhat lower than the typical metal-poor star and inconsistent with the most highly r-enhanced stars. For neutron star mergers to remain viable as the dominant r-process site, future kilonova observations should be preferentially lanthanide-rich (including a population of ∼10% with logXLa> -1.5). These high-XLa kilonovae may be fainter and more rapidly evolving than GW170817, posing a challenge for discovery and follow-up observations. Both optical and (mid-)infrared observations will be required to robustly constrain kilonova lanthanide fractions. If such high-XLa kilonovae are not found in the next few years, that likely implies that the stars with the highest r-process enhancements have a different origin for their r-process elements.

Abstract Copyright: © 2019. The American Astronomical Society. All rights reserved.

Journal keyword(s): Nuclear astrophysics - Neutron stars - R-process - Stellar abundances - Transient sources

VizieR on-line data: <Available at CDS (J/ApJ/882/40): table4.dat refs.dat>

Simbad objects: 210

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