Estudio de estrellas brillantes australes

A plan for a photometric-spectroscopic study of the bright southern stars is described. The work will consist of two parts, the first being the classification in the MK system of all stars down to sixth photographic magnitude; in the second part broad-­band photometry of all these stars will be obtained. For the first part about one thousand spectra were obtained already.Asociación Argentina de Astronomí

Estudio de estrellas brillantes australes

A plan for a photometric-spectroscopic study of the bright southern stars is described. The work will consist of two parts, the first being the classification in the MK system of all stars down to sixth photographic magnitude; in the second part broad-­band photometry of all these stars will be obtained. For the first part about one thousand spectra were obtained already.Asociación Argentina de Astronomí

Jet confinement by magneto-torsional oscillations

Many quasars and active galactic nuclei (AGN) appear in radio, optical, and X-ray maps, as a bright nuclear sources from which emerge single or double long, thin jets. When observed with high angular resolution these jets show structure with bright knots separated by relatively dark regions. Nonthermal nature of a jet radiation is well explained as the synchrotron radiation of the relativistic electrons in an ordered magnetic field. We consider magnetic collimation, connected with torsional oscillations of a cylinder with elongated magnetic field, and periodically distributed initial rotation around the cylinder axis. The stabilizing azimuthal magnetic field is created here by torsional oscillations, where charge separation is not necessary. Approximate simplified model is developed. Ordinary differential equation is derived, and solved numerically, what gives a possibility to estimate quantitatively the range of parameters where jets may be stabilized by torsional oscillations.Comment: accepted for publication in Astrophysics and Space Scienc

Physical Processes in Star Formation

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio

Photoelectric Measurements of Extragalactic Nebulae

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe