Un ammasso stellare può essere immerso in un plasma a milioni di gradi se ospita una popolazione di stelle di Wolf-Rayet. In un ammasso stellare, lo spazio tra le stelle non è semplicemente vuoto, ma può essere riempito da gas (plasma, per la precisione) a temperature di milioni di gradi. Questo dipende principalmente dalla presenza di stelle di grande
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L’evoluzione finale delle stelle massicce presenta ancora diversi punti da chiarire. Sin dal 1975 è stato proposto che le stelle di Wolf-Rayet (WR), stelle di grande massa che hanno espulso i propri strati esterni ricchi di idrogeno ed elio, caratterizzati da temperature elevatissime e venti a migliaia di km/s, siano il prodotto di perdite di massa estremamente intense. Tuttavia, solo stelle con
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Protoplanetary disks are structures of gas and dust that orbit around newly formed stars (referred to as both pre-main-sequence stars and protostars) during their very early evolutionary stages. In fact, they generally disperse in less than 10 million years. Despite their short lifespan, protoplanetary disks play a crucial role. From the perspective of the star, for example, these disks mediate
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Stellar clusters are important targets for studying stellar evolution and, in the case of the youngest star clusters, the products of the star and planet formation processes. Our galaxy hosts a rich population of young stellar clusters, typically with masses of a few hundred solar masses. In the solar neighborhood, for instance, there are only a few young clusters with
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Today in the Milky Way, star formation typically occurs in low-mass environments. Young star clusters (e.g., younger than 10 million years), in fact, typically have a mass of a few hundred solar masses. Nevertheless, our Galaxy hosts a few very massive star-forming regions that can produce tens to hundreds of thousands of stars, including some of the most massive stars
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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
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