Nella struttura e nella dinamica del superammasso stellare Westerlund 1 potrebbe celarsi l’impronta della collisione con il piano della Via Lattea, avvenuta 2 milioni di anni fa. Gli ammassi stellari sono sistemi dinamici estremamente complessi e affascinanti. Cosa li rende così complicati? Innanzitutto, l’evoluzione sia dinamica sia fisica delle loro stelle. Stelle di massa diversa hanno tempi di vita
Un nuovo studio analizza la frequenza con cui stelle di classe spettrale A-F accrescono corpi solidi dai propri sistemi planetari Nelle tumultuose prime fasi evolutive dei giovani sistemi planetari, non è raro che la stella centrale accresca pianeti e planetesimali (i piccoli corpi rocciosi da cui si formano i pianeti più grandi). Non potendo risalire alle prime fasi del
Grazie al progetto EWOCS, identificata per la prima volta la popolazione di oggetti sub-stellari di un superammasso stellare Attraversando il diagramma di Hertzsprung-Russell dalle masse maggiori a quelle minori, si incontrano stelle con struttura interna, proprietà ed evoluzione totalmente diverse. Il limite inferiore in termini di massa per una stella è di 0.075 masse solari: al di sotto di
La corona del Sole è una struttura che si estende per diversi raggi solari ed è popolata da plasma a bassa densità e a milioni di gradi, molto più caldo di quello in fotosfera e cromosfera. Cosa riscalda il plasma coronale fino a temperature così elevate? Sembra che la causa sia una combinazione di complessi fenomeni di natura magnetica.
The analysis of a long X-ray observation reveals the nature of the mysterious star Wd1-9: a binary system containing a star that has recently evolved into the Wolf-Rayet phase, after expelling the outer layers of its atmosphere, which were accreted onto the companion star. Among the at least one hundred billion stars hosted by our Galaxy, there are a
A new theoretical study shows that the holes in the structure observed by the James Webb Space Telescope called “Green Monster” within the Cassiopeia A (Cas A) supernova remnant is due to the interaction between a pre-existing layer of circumstellar material, impacted by the supernova shock wave, and elongated stellar fragments produced by hydrodynamic instabilities. Supernova remnants are objects of
The star-forming regions can differ significantly from one another, particularly in terms of the population of massive stars (with masses exceeding about 10 solar masses) and stellar density (defined as the number of stars per unit volume). These aspects can vary drastically from one region to another. Such differences are extremely important, as massive stars create environments dominated by high-energy
The properties and morphology of supernova remnants result from complex physical processes in the progenitor star, both in the stages preceding the explosion and during the event itself. This involves the rapid collapse of the core, occurring in seconds, up to the shock wave reaching the star’s surface. Additionally, the supernova’s evolution is shaped by interactions between the star’s expelled
The characterization of exoplanetary atmospheres is one of the most active research fields in modern astrophysics, made possible by the development of dedicated instruments and techniques. The basic idea of this research is quite simple: obtaining spectroscopic observations of stars with planets during the transit of the planet in front of its star, which is the moment when part of
The role of supernova remnants (expanding clouds produced by supernovae) in the acceleration of cosmic rays (high-energy particles present in various astrophysical environments) has been known since 1995. The discovery, made by astronomers from Kyoto University, was made possible by identifying the presence of non-thermal X-ray emission in the supernova remnant SN 1006. X-rays are a type of high-energy radiation
