相关论文: Molecules as Tracers of PN Structure

A summary is given of planetary nebulae abundances from ISO measurements. It is shown that these nebulae show abundance gradients (with galactocentric distance), which in the case of neon, argon, sulfur and oxygen (with four exceptions) are…

We simulate the formation of bipolar planetary nebulae (PNe) through very short impulsive mass ejection events from binary systems, where the asymptotic giant branch (AGB) star ejects a mass shell that is accelerated by jets launched from a…

Globular clusters contain many stars with surface abundance patterns indicating contributions from hydrogen burning products, as seen in the anti-correlated elemental abundances of e.g. sodium and oxygen, and magnesium and aluminium.…

Biomolecular structures are assemblies of emergent anisotropic building modules such as uniaxial helices or biaxial strands. We provide an approach to understanding a marginally compact phase of matter that is occupied by proteins and DNA.…

Studies of molecular clouds and young stars near the sun have provided invaluable insights into the process of star formation. Indeed, much of our physical understanding of this topic has been derived from such studies. Perhaps the two most…

Organic macromolecular matter is the dominant carrier of volatile elements such as carbon, nitrogen, and noble gases in chondrites -- the rocky building blocks from which Earth formed. How this macromolecular substance formed in space is…

Galactic nuclei are unique laboratories for the study of processes connected with the accretion of gas onto supermassive black holes. At the same time, they represent challenging environments from the point of view of stellar dynamics due…

We study two dimensional Fabry-Perot interferometric observations of the nearby face-on late-type spiral galaxy, NGC 628. We investigate the role of the individual HII regions together with the large-scale gravitational mechanisms which…

Angular momentum plays a crucial role in the formation of stars and planets. It has long been noticed that parcels of gas in molecular clouds need to reduce their specific angular momentum by 6 to 7 orders of magnitude to participate in the…

Preplanetary nebulae and planetary nebulae are evolved, mass-losing stellar objects that show a wide variety of morphologies. Many of these nebulae consist of outer structures that are nearly spherical (spiral/shell/arc/halo) and inner…

Chemistry plays a particular role in astrophysics. After atomic hydrogen, helium and their ions, the Universe probably contains more mass in molecules than in any other species. Molecule formation in the early, pre-galactic Universe may…

HI observations have revealed in several shell galaxies the presence of gaseous shells slightly displaced from the stellar shells radially, in the outward direction. We propose a mechanism to form this gaseous shells, based on the…

Shells are fine stellar structures identified by their arc-like shapes present around a galaxy and currently thought to be vestiges of galaxy interactions and/or mergers. The study of their number, geometry, stellar populations and gas…

We investigate the star-formation in cometary tails of galaxies in clusters. In particular, we focus on the evolution of molecular clouds in the tails that generate the stars. Assuming that the gas tails had been derived from the galaxies…

The origin of the large scale structure in the universe - galaxies, quasars, clusters, voids, sheets - is one of the most important questions in cosmology. One can show that some non-thermal energy density fluctuations must have been…

We show that the formation of membrane tubes (or membrane tethers), which is a crucial step in many biological processes, is highly non-trivial and involves first order shape transitions. The force exerted by an emerging tube is a…

One of the fundamental astrobiology questions is how life has formed in our Solar System. In this context the formation and stability of abiotic organic molecules such as CH4, formic acid and amino acids, is important for understanding how…

Molecular oxygen (O2) will be an important molecule in the search for biosignatures in terrestrial planetary atmospheres in the coming decades. In particular, O2 combined with a reducing gas is thought to be strong evidence for…

Planetary Nebulae represent a powerful window into the evolution of low-intermediate mass stars that have undergone extensive mass-loss. The nebula manifests itself in an extremely wide variety of shapes, but exactly how the mass lost is…

Stellar winds form an integral part of astronomy. The solar wind affects Earth's magnetosphere, while the winds of hot massive stars are highly relevant for galactic feedback through their mechanical wind energy. In different parts of the…