Dischi protoplanetari in Orion A non mostrano effetti ambientali sulla quantità di materia che accrescono sulla stella centrale I dischi protoplanetari sono strutture a forma di disco osservate attorno a stelle giovani, tipicamente con un’età inferiore ai 10 milioni di anni. Sono oggetti di grande interesse scientifico per vari motivi, principalmente perché rappresentano la struttura in cui si formano
Star clusters are a product of the star formation process. During their gravitational collapse, in fact, molecular clouds fragment forming hundreds or even thousands of stars. During the first few tens of million of years of their evolution, the young stars formed in a cloud are bound by the intense mutual gravitational attraction, forming a stellar cluster. Star clusters are important
The chemical history of Lithium abundance in the Universe is very complex. This chemical element has been first produced during the Big Bang, even if in very small quantities compared with hydrogen and helium. Since then, lithium is continuously created and destroyed by several processes occurring in stellar interior. This means that the lithium abundances we observe in stars today
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
di Mario Giuseppe Guarcello ( segui mguarce) Lo studio dell’emissione di raggi X dalle stelle offre molte diagnostiche di fenomeni stellari ad alta energia. Nelle stelle massive (di classe spettrale O le B più calde) raggi X “soffici” (con energia generalmente minore di 1keV, corrispondente a temperature minori di 10 milioni di gradi) sono emessi in shock nei
