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This document describes the first proof-of-concept version of the PYTHIA7 program. PYTHIA7 is a complete re-write of the PYTHIA program in C++. It is mainly intended to be a replacement for the `Lund' family of event generators, but is also a framework with a structure suitable for implementing any event generator model. In this document, the structure of the program is presented both from the use

Many white dwarf stars show signs of having accreted smaller bodies, implying that they may host planetary systems. A small number of these systems contain gaseous debris discs, visible through emission lines. We report a stable 123.4-minute periodic variation in the strength and shape of the Ca II emission line profiles originating from the debris disc around the white dwarf SDSS J122859.93+10403

Jupiter Trojans are a resonant asteroidal population characterised by photometric colours that are compatible with trans-Neptunian objects, high inclinations, and an asymmetric distribution of the number of asteroids between the two swarms. Different models have been proposed to explain the high inclination of the Trojans and to interpret their relation with the Trans-Neptunian objects, but none o

Supermassive black holes are found in most galactic nuclei. A large fraction of these nuclei also contain a nuclear stellar cluster surrounding the black hole. Here we consider the idea that the nuclear stellar cluster formed first and that the supermassive black hole grew later. In particular we consider the merger of three stellar clusters to form a nuclear stellar cluster, where some of these c

We investigate the origin of the period distribution of giant planets. We fit the bias-corrected distribution of gas-giant planets inside 300 d found by Santerne et al. using a planet formation model based on pebble accretion. We investigate two possible initial conditions: a linear distribution of planetary seeds, and seeds injected exclusively on the water and CO icelines. Our simulations exclud

The processes that led to the formation of the planetary bodies in the Solar system are still not fully understood. Using the results obtained with the comprehensive suite of instruments onboard the European Space Agency's Rosetta mission, we present evidence that comet 67P/Churyumov-Gerasimenko likely formed through the gentle gravitational collapse of a bound clump of mm-sized dust aggregates ('

Swan bands-characteristic molecular absorption features of the C2 molecule-are a spectroscopic signature of carbon-enhanced stars. They can also be used to identify carbonenhanced metal-poor (CEMP) stars. The GALAH (GALactic Archaeology with Hermes) is a magnitude-limited survey of stars producing high-resolution, high-signal-to-noise spectra. We used 627 708 GALAH spectra to search for carbon-enh

The Galactic Center is one of the most dense stellar environments in the Galaxy and is considered to be a plausible place to harbor many neutron stars. In this brief review, we summarize observational efforts in search of neutron stars within a few degrees about the Galactic Center. Up to 10% of Galactic neutron stars may reside in this central region and it is possible that more than a thousand n

Context. Pismis 18 is a moderately populated, intermediate-Age open cluster located within the solar circle at a Galactocentric distance of about seven kpc. Few open clusters have been studied in detail in the inner disc region before the Gaia-ESO Survey. Aims. New data from the Gaia-ESO Survey allowed us to conduct an extended radial velocity membership study as well as spectroscopic metallicity

The globular clusters of large spiral galaxies can be divided into two populations: one that formed in situ and one that comprises clusters tidally stripped away from other galaxies. In this paper, we investigate the contribution to the outer globular cluster population in the M31 galaxy through donation of clusters from dwarf galaxies. We test this numerically by comparing the contribution of glo

Observations find a median star formation efficiency per free-fall time in Milky Way Giant Molecular Clouds (GMCs) of the order of ϵff∼1 per cent with dispersions of ∼0.5dex⁠. The origin of this scatter in ϵff is still debated and difficult to reproduce with analytical models. We track the formation, evolution and destruction of GMCs in a hydrodynamical simulation of a Milky Way-like galaxy and by

Modelling the propagation of supernova (SN) bubbles, in terms of energy, momentum, and spatial extent, is critical for simulations of galaxy evolution which do not capture these scales. To date, small-scale models of SN feedback predict that the evolution of above-mentioned quantities can be solely parametrized by average quantities of the surrounding gas, such as density. However, most of these s

Context. In the era of large high-resolution spectroscopic surveys such as Gaia-ESO and APOGEE, high-quality spectra can contribute to our understanding of the Galactic chemical evolution by providing abundances of elements that belong to the different nucleosynthesis channels, and also by providing constraints to one of the most elusive astrophysical quantities: stellar age. Aims. Some abundance

Variational methods are used to calculate structural and thermodynamical properties of a titrating polyelectrolyte in a discrete representation. In the variational treatment, the Coulomb potentials are emulated by harmonic repulsive forces between all monomers; the force constants are used as variational parameters. The accuracy of the variational approach is tested against Monte Carlo data. Excel

Many observed giant planets lie on eccentric orbits. Such orbits could be the result of strong scatterings with other giant planets. The same dynamical instability that produces giant planet scatterings can also alter the orbits of terrestrial planets. For example, a habitable rocky planet in the system can be ejected or transported to an orbit outside the habitable zone. Therefore, there is a lin