[en] Nucleosynthetic isotopic anomalies in meteorites and planetary objects contribute to our understanding of the formation of the solar system. Isotope systematics of chondrites demonstrate the existence of a physical separation between isotopic reservoirs in the solar system. The isotopic composition of atmospheric xenon (Xe) indicates that its progenitor, U-Xe, is depleted in ¹³⁴Xe and ¹³⁶Xe isotopes relative to solar or chondritic end-members. This deficit supports the view that nucleosynthetic heterogeneities persisted during the solar system formation. Measurements of xenon emitted from comet 67P/Churyumov–Gerasimenko (67P) identified a similar, but more extreme, deficit of cometary gas in these isotopes relative to solar gas. Here we show that the data from 67P demonstrate that two distinct sources contributed xenon isotopes associated with the r-process to the solar system. The h-process contributed at least 29% (2σ) of solar system ¹³⁶Xe. Mixtures of these r-process components and the s-process that match the heavy isotope signature of cometary Xe lead to depletions of the precursor of atmospheric Xe in p-only isotopes. Only the addition of pure p-process Xe to the isotopic mixture brings ¹²⁴Xe/¹³²Xe and ¹²⁶Xe/¹³²Xe ratios back to solar-like values. No pure p-process Xe has been detected in solar system material, and variation in p-process Xe isotopes is always correlated with variation in r-process Xe isotopes. In the solar system, p-process incorporation from the interstellar medium happened before incorporation of r-process nuclides or material in the outer edge of the solar system carries a different mixture of presolar sources as have been preserved in parent bodies.

[en] The impact of nuclear mass uncertainties on the r-process abundances has been systematically studied with the classical r-process model by varying the mass of every individual nucleus in the range of ±0.1 to ±3.0 MeV based on six different mass models. A new quantitative relation between the uncertainties of r-process abundances and those of the nuclear masses is extracted, i.e., a mass uncertainty of ±0.5 MeV would lead to an abundance uncertainty of a factor around 2.5. It is found that this conclusion holds true for various mass models.

[en] We present and discuss three extremely r-process enhanced stars located in the massive dwarf spheroidal galaxy Fornax. These stars are very unique with an extreme Eu enrichment (1.25 ≤ [Eu/Fe]≤1.45) at high metallicities (−1.3 ≤ [Fe/H]≤−0.8). They have the largest Eu abundances ever observed in a dwarf galaxy opening new opportunities to further understand the origin of heavy elements formed by the r-process. We derive stellar abundances of Co, Zr, La, Ce, Pr, Nd, Er, and Lu using one-dimensional, local thermodynamic equilibrium codes and model atmospheres in conjunction with state-of-the art yield predictions. We derive Zr in the largest sample of stars (105) known to date in a dwarf galaxy. Accurate stellar abundances combined with a careful assessment of the yield predictions have revealed three metal-rich stars in Fornax showing a pure r-process pattern. We define a new class of stars, namely, Eu-stars, as r-II stars (i.e., [Eu/Fe] > 1) at high metallicities (i.e., [Fe/H] ≳ −1.5). The stellar abundance pattern contains Lu, observed for the first time in a dwarf galaxy, and reveals that a late burst of star formation has facilitated extreme r-process enhancement late in the galaxy’s history (<4 Gyr ago). Due to the large uncertainties associated with the nuclear physics input in the yield predictions, we cannot yet determine the r-process site leading to the three Eu-stars in Fornax. Our results demonstrate that extremely r-rich stars are not only associated with ultra-faint low-mass dwarf galaxies, but can be born also in massive dwarf galaxies.

[en] The rate and location of binary neutron star (BNS) mergers are determined by a combination of the star formation history and the delay-time distribution (DTD) function. In this paper, we couple the star formation rate histories from the IllustrisTNG model to a series of varied assumptions for the BNS DTD to make predictions for the BNS merger host galaxy mass function. These predictions offer two outcomes: (i) in the near term they influence the BNS merger event follow-up strategy by scrutinizing where most BNS merger events are expected to occur, and (ii) in the long term they constrain the DTD for BNS merger events once the host galaxy mass function is observationally well determined. From our fiducial model analysis, we predict that 50% of BNS mergers will occur in host galaxies with stellar mass between 10¹⁰ and 10¹¹ M _⊙, 68% between 4 × 10⁹ and 3 × 10¹¹ M _⊙, and 95% between 4 × 10⁸ and 2 × 10¹² M _⊙. We find that the details of the DTD employed do not have a strong effect on the peak of the host mass function. However, varying the DTD provides enough spread that the true DTD can be determined from enough electromagnetic observations of BNS mergers. Knowing the true DTD can help us determine the prevalence of BNS systems formed through highly eccentric and short-separation fast-merging channels and can constrain the dominant source of r-process material.

[en] The first detection of binary black hole merger by LIGO-Virgo detectors was a landmark discovery in the 21st century physics. By now, two observational runs of the ground based gravitational wave detectors are complete. The gravitational wave window has observed ten binary black hole mergers and showed unique signatures about stellar mass black hole population which will be discussed in this talk. (author)

No abstract available

[en] A brief outline of the Surrogate reaction method, an indirect approach for determining compound-nuclear reaction cross sections, is given. The assumptions introduced in the analysis of a typical Surrogate experiment are discussed and prospects for using the Surrogate method to obtain cross sections relevant to the astrophysical s-process are considered

[en] The existence of planets born in environments highly perturbed by a stellar companion represents a major challenge to the paradigm of planet formation. In numerical simulations, the presence of a close binary companion stirs up the relative velocity between planetesimals, which is fundamental in determining the balance between accretion and erosion. However, the recent discovery of circumbinary planets by Kepler establishes that planet formation in binary systems is clearly viable. We perform N-body simulations of planetesimals embedded in a protoplanetary disk, where planetesimal phasing is frustrated by the presence of stochastic torques, modeling the expected perturbations of turbulence driven by the magnetorotational instability. We examine perturbation amplitudes relevant to dead zones in the midplane (conducive to planet formation in single stars), and find that planetesimal accretion can be inhibited even in the outer disk (4-10 AU) far from the central binary, a location previously thought to be a plausible starting point for the formation of circumbinary planets.

[en] While the primordial (or Big Bang) nucleosynthesis delivers important clues about the conditions in the high red-shift universe (termed far-field cosmology), the nucleosynthesis of the heavy elements beyond iron by the r-process or the s-process deliver information about the early phase and history of the Galaxy (termed near-field cosmology). In particular, the r-process nucleosynthesis is unique, because it is a primary process that helps to associate individual stars with the composition of the protocloud. The present contribution is intended to give a brief overview about these nucleosynthesis processes and describe their link to the early universe, stellar evolution and to the chemical evolution of the Galaxy. The focus of this present contribution is on illumination the role of nucleosynthesis in the Universe. Owing to the complexity of this subject, a general scenario is more appealing to address interested readers. (paper)

[en] We present an abundance analysis based on high-resolution spectra of eight stars selected to span the full range in metallicity in the Draco dwarf spheroidal (dSph) galaxy. We find that [Fe/H] for the sample stars ranges from -1.5 to -3.0 dex. Combining our sample with previously published work for a total of 14 luminous Draco giants, we show that the abundance ratios [Na/Fe], [Mg/Fe], and [Si/Fe] for the Draco giants overlap those of Galactic halo giants at the lowest [Fe/H] probed, but are significantly lower for the higher Fe-metallicity Draco stars. For the explosive α-elements Ca and Ti, the abundance ratios for Draco giants with [Fe/H] > - 2.4 dex are approximately constant and slightly subsolar, well below values characteristic of Galactic halo stars. The s-process contribution to the production of heavy elements begins at significantly lower Fe metallicity than in the Galactic halo. Using a toy model we compare the behavior of the abundance ratios within the sample of Draco giants with those from the literature of Galactic globular clusters, and the Carina and Sgr dSph galaxies. The differences appear to be related to the timescale for buildup of the heavy elements, with Draco having the slowest rate. We note the presence of a Draco giant with [Fe/H] <-3.0 dex in our sample, and reaffirm that the inner Galactic halo could have been formed by early accretion of Galactic satellite galaxies and dissolution of young globular clusters, while the outer halo could have formed from those satellite galaxies accreted later.