New Study Seems Confirm Massive Stars are Born as Giants

A new study seems to confirm that massive stars generally start out life much bigger than they will be in maturity. Astronomers from the University of Amsterdam got a rare look at a massive star in the process of forming and found that the star will contract until it has reached a stable equilibrium. The researchers studied the young star B275. Star B275 lies in the Omega Nebula, also called the Swan Nebula or Messier 17. This hotbed of gas, dust and young stars lies approximately 5,500 light-years from Earth, in the direction of the Sagittarius constellation. The new study results indicate that B275 is about three times larger than stars that are about seven times more massive than our sun  and have  reached   the  so-called main sequence  phase of their lives.

According to researchers core temperature of B275 is now high enough for the star to begin burning hydrogen, but the star will contract until it reaches a stable equilibrium, in which the energy production in the core exactly balances out the radiation loss at the stellar surface. Observations from the Very Large Telescope also showed that the surface temperature of B275 was significantly lower than usual for a star its size that is 1,600 times more luminous than the sun. To account for this discrepancy, the researchers assigned a larger radius to the newborn star which matches the sharp spectral observations taken of B275 that show it is a stellar giant.
source:www.space.com