The amount of gas that is converted into stars by the star formation process is described by the star formation rate. For instance, in the Milky Way today between 0.7 and 1.5 solar masses of gas are converted into stars each year. However, this a mean value across our Galaxy, since locally clouds can start forming stars at higher rates
The James Webb Telescope (JWST) will be the most complex and powerful telescope ever launched into space. Built by a consortium formed by NASA, ESA, and the Canadian Space Agency (CSA), thanks to its primary mirror with a diameter of 6.5 meters (for comparison, the mirror of the Hubble Space Telescope has a diameter of 2.5 meters) and its four
At a distance of about 160 light years, the stellar association TW Hydrae is a benchmark for the study of pre-main sequence stars and their protoplanetary disks. Pre-main sequence stars are a few million years old stars, still gravitationally contracting and not powered yet by the thermonuclear reactions. They are often surrounded by disks of dust and gas called “protoplanetary
Stars form from the gravitational contraction of large gas clouds. This process may occur in two different modes: It may be fast, with a characteristic timescale dictated by the free fall of gas onto the forming stars, or it may be slow, sustained by turbulence and magnetic field. In the former case stars form over a short period, while in
OB associations have a rich population of massive stars (O and B stars), which are young and typically dispersed over large regions of the sky. While these massive stars can be easily recognized thanks to their intense luminosity, it is very hard to select the low mass stars belonging to OB associations. This because without evident stellar concentrations, these stars
Stars form from the gravitational collapse of large interstellar clouds. During the process, the clouds fragment in smaller clouds, forming clusters and associations of stars counting from few tens to several hundred thousands stars. The star formation process typically is not a monolithic process, e.g. with a single large event of star formation occurring rapidly and forming all the stars
OB associations are objects of great importance, since they contain a rich population of OB stars. Despite their paucity, OB stars have a strong impact on the evolution of their parental clouds, nearby stars, and the whole Galaxy. For instance, their intense UV emission affects the evolution of the parental cloud and the star formation process in it, sometimes triggering
In the Milky Way one of the main modes of star formation is in stellar clusters, which remain associated with their parental cloud for about 5-10 million years. This makes the star forming regions complex targets, characterised by rich stellar populations packed into small regions, sometime even with massive stars, and clouds whose morphology and properties are affected by the
OB associations are groups of massive stars (with spectral type O and B, more massive than 3.5 solar masses) which typically cover wide regions in the sky. The presence of such a rich population of massive stars suggests the presence of even a larger population of low-mass stars. There exists, in fact, a relation between the number of stars in
di Mario Giuseppe Guarcello ( segui mguarce) È stato pubblicato sul sito del satellite Chandra della NASA un articolo (link) interamente dedicato agli studi INAF-OAPA/CfA della regione di formazione stellare nota come Nebulosa dell’Aquila o M16, contenente l’ammasso stellare NGC 6611, realizzato con vari telescopi operativi in diverse bande dello spettro elettromagnetico, tra cui il satellite Chandra della
