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Neutron-star mergers were recently confirmed as sites of rapid-neutron-capture (r-process) nucleosynthesis. However, in Galactic chemical evolution models, neutron-star mergers alone cannot reproduce the observed element abundance patterns…

The ejecta from binary neutron star mergers, which powers its associated kilonova, can inform us about source properties, merger dynamics, and the dense nuclear matter equation of state. While now in the era of multi-messenger astronomy, we…

High Energy Astrophysical Phenomena · Physics 2025-04-08 Amelia Henkel , Francois Foucart , Selah Melfor , Samaya Nissanke , Alexandra Wernersson , Uddipta Bhardwaj

In the context of kilonova (KN) modeling, the present work focusses on large-scale atomic data and opacity computations for all heavy elements from Ca to Lr, with a special effort on lanthanides and actinides, for a grid of typical KN…

The spectra of singly ionised Strontium and Yttrium (Sr {\sc ii} and Y {\sc ii}) have been proposed as identifications of certain spectral features in the AT2017gfo spectrum. With the growing demand for NLTE simulations of Kilonovae, there…

High Energy Astrophysical Phenomena · Physics 2024-07-02 Leo Mulholland , Niall McElroy , Fiona McNeill , Stuart Sim , Connor Ballance , Catherine Ramsbottom

The mergers of neutron stars expel a heavy-element enriched fireball which can be observed as a kilonova. The kilonova's geometry is a key diagnostic of the merger and is dictated by the properties of ultra-dense matter and the energetics…

High Energy Astrophysical Phenomena · Physics 2023-02-15 Albert Sneppen , Darach Watson , Andreas Bauswein , Oliver Just , Rubina Kotak , Ehud Nakar , Dovi Poznanski , Stuart Sim

We investigate the ejecta from black hole - neutron star mergers by modeling the formation and interaction of mass ejected in a tidal tail and a disk wind. The outflows are neutron-rich, giving rise to optical/infrared emission powered by…

High Energy Astrophysical Phenomena · Physics 2017-07-26 Rodrigo Fernández , Francois Foucart , Daniel Kasen , Jonas Lippuner , Dhruv Desai , Luke F. Roberts

The detection of GW170817 and the accompanying electromagnetic counterpart, AT2017gfo, have provided an important set of observational constraints for theoretical models of neutron star mergers, nucleosynthesis, and radiative transfer for…

The merger of binary neutron stars (NSs) ejects a small quantity of neutron rich matter, the radioactive decay of which powers a day to week long thermal transient known as a kilonova. Most of the ejecta remains sufficiently dense during…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Brian D. Metzger , Andreas Bauswein , Stephane Goriely , Daniel Kasen

We investigate the nucleosynthesis of heavy elements in the winds ejected by accretion disks formed in neutron star mergers. We compute the element formation in disk outflows from hypermassive neutron star (HMNS) remnants of variable…

High Energy Astrophysical Phenomena · Physics 2017-09-26 Jonas Lippuner , Rodrigo Fernández , Luke F. Roberts , Francois Foucart , Daniel Kasen , Brian D. Metzger , Christian D. Ott

A kilonova is a short-lived explosive event in the universe, resulting from the merger of two compact objects. Despite its importance as a primary source of heavy elements through r-process nucleosynthesis, its nature is not well…

High Energy Astrophysical Phenomena · Physics 2023-11-22 Donggeun Tak , Z. Lucas Uhm , James H. Gillanders

To better characterize the abundance patterns produced by the r-process, we have derived new abundances or upper limits for the heavy elements zinc (Zn), yttrium (Y), lanthanum (La), europium (Eu), and lead (Pb). Our sample of 161…

Solar and Stellar Astrophysics · Physics 2015-05-20 I. U. Roederer , J. J. Cowan , A. I. Karakas , K. -L. Kratz , M. Lugaro , J. Simmerer , K. Farouqi , C. Sneden

We determine the abundances of neutron-capture elements from Sr to Eu for five very-metal-poor stars (-3<[Fe/H]<-2) in the Milky Way halo to reveal the origin of light neutron-capture elements. Previous spectroscopic studies have shown…

Solar and Stellar Astrophysics · Physics 2017-03-03 Misa Aoki , Yuhri Ishimaru , Wako Aoki , Shinya Wanajo

In this study we incorporate a new grid of kilonova simulations produced by the Monte Carlo radiative transfer code SuperNu in an inference pipeline for astrophysical transients, and evaluate their performance. These simulations contain…

High Energy Astrophysical Phenomena · Physics 2025-05-23 Brendan L. King , Soumi De , Oleg Korobkin , Michael W. Coughlin , Peter T. H. Pang

Mergers of binary neutron stars are multimessenger sources of gravitational waves that have an optical luminous counterpart, commonly referred to as 'kilonova'. Inspired by the detection of GW170817, intensive searches have been conducted…

High Energy Astrophysical Phenomena · Physics 2023-08-23 Runduo Liang , Zhengyan Liu , Lei Lei , Wen Zhao

r-Process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these transients depend on the composition of the ejecta, which…

High Energy Astrophysical Phenomena · Physics 2015-12-23 Jonas Lippuner , Luke F. Roberts

Long-lived radioactive nuclei play an important role as nucleo-cosmochronometers and as cosmic tracers of nucleosynthetic source activity. In particular nuclei in the actinide region like thorium, uranium, and plutonium can testify to the…

Solar and Stellar Astrophysics · Physics 2016-04-27 S. Goriely , H. -Th. Janka

Observations of metal-poor stars indicate that at least two different nucleosynthesis sites contribute to the production of r-process elements. One site is responsible for the production of light r-process elements Z<~50 while the other…

High Energy Astrophysical Phenomena · Physics 2015-06-17 G. Martínez-Pinedo , T. Fischer , L. Huther

It has been shown that proton ingestion episodes can happen in the formation of hot-subdwarf stars, and that neutron-capture processes are possible in those cases. Moreover, some helium-rich hot subdwarfs display extraordinarily high…

Solar and Stellar Astrophysics · Physics 2025-07-16 T. Battich , M. M. Miller Bertolami , A. Weiss , M. Dorsch , A. M. Serenelli , S. Justham

The electromagnetic transients accompanying compact binary mergers ($\gamma$-ray bursts, afterglows and 'macronovae') are crucial to pinpoint the sky location of gravitational wave sources. Macronovae are caused by the radioactivity from…

Observed abundances of Z ~ 40 elements in metal-poor stars vary from star to star, indicating that the rapid and slow neutron capture processes may not contribute alone to the synthesis of elements beyond iron. The weak r-process was…