Related papers: An Oort cloud origin of the Halley-type comets
Explaining the origin of the orbit of 2000 CR105 (a ~ 230AU, q ~ 45AU) is a major test for our understanding of the primordial evolution of the outer Solar System. Gladman et al. (2001) showed that this objects could not have been a normal…
The D/H ratio in cometary water is believed to be an important indicator of the conditions under which icy planetesimals formed and can provide clues to the contribution of comets to the delivery of water and other volatiles to Earth.…
We compare the predictions of three physical models for the origin of the hot halo gas with the observed halo X-ray emission, derived from 26 high-latitude XMM-Newton observations of the soft X-ray background between $l=120\degr$ and…
The new cometary catalogue containing data for almost 300 long-period comets that were discovered before 2018 is announced (the CODE catalogue). This is the first catalogue containing cometary orbits in five stages of their dynamical…
Outflowing motions, whether a wind launched from the disk, a jet launched from the protostar, or the entrained molecular outflow, appear to be an ubiquitous feature of star formation. These outwards motions have a number of root causes, and…
Jupiter-family comet (JFC) P/2021 HS (PANSTARRS) only exhibits a coma within a few weeks of its perihelion passage at 0.8~au, which is atypical for a comet. Here we present an investigation into the underlying cause using serendipitous…
Cometary meteoroid trails exist in the vicinity of comets, forming fine structure of the interplanetary dust cloud. The trails consist predominantly of cometary particles with sizes of approximately 0.1 mm to 1 cm which are ejected at low…
The Scattered Disk Objects (SDOs) are a population of trans-Neptunian bodies with semimajor axes $50< a \lesssim 1000$ au and perihelion distances $q \gtrsim 30$ au. The detached SDOs with orbits beyond the reach of Neptune (roughly…
We analyze findings of the Stardust mission that brought to the Earth dust from the 81P/Wild 2 coma. Just as the data of the Deep Impact mission to 9P/Tempel 1, they are at odds with the widely accepted condensation/sublimation comet…
We present a chemical kinetics model of the solid-phase chemical evolution of a comet, beginning with a long period of cold-storage in the Oort Cloud, followed by five orbits that bring the comet close to the Sun. The chemical model is…
We investigate what may be the origin of the presently observed spatial distribution of the mass of the Galactic Old Halo globular cluster system. We propose its radial mass density profile to be a relic of the distribution of the cold…
A previous study suggests that the observed exponential character of the surface brightness profiles in the coma around the interstellar comet 3I/ATLAS at 4 au can be explained as a consequence of the destruction of the icy scattering…
Aims. Investigate the influence of cluster environments on asteroids, with special attention towards captured material. Methods. Using numerical methods, a sub-virial fractally distributed star-forming region and a virialised Plummer…
High-Velocity Clouds (HVCs) are a major fuel reservoir for star formation in the Galactic disk. Determining their origin and kinematics is thus crucial for understanding Galactic evolution. In this paper, we employ simple test-particle…
The Hawking radiation is one of the most interesting phenomena predicted by the theory of quantum field in curved space. The origin of Hawking radiation is closely related to the fact that a particle which marginally escapes from collapsing…
We assume a distribution of clouds optically thick for electron scattering (OTCM) which are moderately optically thin for absorption and we consider them as a model of the mean quasar spectrum of Laor et al. (1997). We show that the model…
The Oort Cloud's dynamical evolution is significantly influenced by both the galactic tide and stellar flybys. This study investigates the particular case of HD7977's close encounter 2.47 Myr ago, which likely repopulated the Inner Oort…
Large HI shells, with diameters of hundreds of pc and expansion velocities of 10-20kms-1 are well observed features of local gas rich galaxies. These shells could well be predicted as a result of the impact of OB associations on the ISM,…
After its formation, a young star spends some time traversing the molecular cloud complex in which it was born. It is therefore not unlikely that, well after the initial cloud collapse event which produced the star, it will encounter one or…
We describe the result of our numerical orbit simulation which traces dynamical evolution of new comets coming from the Oort Cloud. We combine two dynamical models for this purpose. The first one is semi-analytic, and it models an evolving…