When a 3 M_⨀ Protostar Forms,it Starts Out at the Top

Essay

When a 3 M_⨀ protostar forms,it starts out at the top of the Hayashi track with a luminosity of 4,000 L_⨀ and a temperature of 3600 K.What is its radius at this point (give the answer in units of R_⨀),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_⨀? For reference,the Sun's temperature is 5800 K.