If you visit NASA’s website, they define a protostar as the “hot core at the heart of the collapsing cloud that will one day become a star”.
19-year-old Martina Arduino, who graduated from La Scala’s Ballet Academy just a year ago was entrusted last night, as her first ever principal role(s), with the Odette/Odile characters in Alexei Ratmansky’s new Swan Lake. She is not yet a star, but she’s certainly a protostar.