When a 3 M= _$\odot$ =protostar Forms, It Starts Out at the Top of the at the Top

Essay

When a 3 M= _$\odot$ =protostar forms, it starts out at the top of the Hayashi track with a luminosity of 4,000 L= _$\odot$ = and a temperature of 3600 K. What is its radius at this point (give the answer in units of R= _$\odot$ =), and how many times larger is it at this stage compared to its radius as a main-sequence star, which is about 2.5 R= _$\odot$ =? For reference, the Sun's temperature is 5800 K.