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
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di Mario Giuseppe Guarcello ( segui mguarce) Lo studio dei resti di supernova, nubi formate dalle esplosioni di supernova, sono oggetti di grande interesse scientifico. Queste nebulose, infatti, non sono semplicemente il residuo di uno dei fenomeni più violenti che avvengono nell’Universo (un’esplosione di supernova dal collasso di una stella massiva, ossia le “core-collapse supernovae”, produce un’energia pari
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Interstellar and circumstellar dust plays a fundamental role in several astrophysical processes and environments, such as in protoplanetary disks, which are structure orbiting pre-main sequence stars for less than ten million years, and which are the site of planet formation. For instance, despite the mass of protoplanetary disks is dominated by gas (mainly hydrogen), their dust grains are mainly responsible
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A recent study by a team of researchers of INAF-Astronomical Observatory of Palermo, the University of Palermo, and the University of Madrid, recently published on the Astrophysical Journal, shows that enormous flares in the young stars in Orion are due to large magnetic loops connecting the stars and their protoplanetary disks, confining plasma oscillating from disk to the star.
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In the last years the number of known exoplanets has grown quickly thanks to missions such as Kepler and CoRoT and instruments such as HARPS-N, mounted on the Telescopio Nazionale Galileo, which are designed to identify exoplanets with the method of transits or radial velocity. We have understood now that the presence of exoplanets is a common features in stars
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The study of the X-ray emission from stars provides an unmatched view of those energetic phenomena occurring in stars. In massive stars (O and early B stars), soft X-ray photons (less energetic than about 1 keV) are emitted from shocks in stellar winds. More energetic photons (the hard X-ray emission) is due to colliding stellar winds in binary systems or
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di Mario Giuseppe Guarcello ( segui mguarce) Solido, liquido e gassoso….questi sono gli stati della materia a cui siamo abituati sulla Terra. Nell’Universo non è esattamente cosi’. Il 99% della materia conosciuta (ed osservabile) nell’Universo infatti si trova sotto forma di plasma, uno stato che sulla Terra si trova naturalmente nei fulmini o nelle aurore boreali. Cosa
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Exoplanets research has a wide appeal on the public and the scientific community. This mainly thanks to the results of successful missions such as CoRoT and Kepler, which allowed us to identify to date 3610 exoplanets, with more than 2000 candidates (link). However, the search for exoplanets is only part of this important branch of astrophysics, which faces several important questions still without answer:
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Pur essendo sempre spettacolare ed affascinante, l’Universo appare diverso quando lo si osserva in diverse bande dello spettro elettromagnetico. In particolare, quello osservabile ai raggi X è un Universo dominato da fenomeni violenti e particolarmente energetici: esplosioni e resti di supernovae; corone stellari con plasma a milioni di gradi e dominate da brillamenti ed espulsioni di massa; gli esotici oggetti compatti in
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