For the 26th birthday of NASA’s Hubble Space Telescope, astronomers are highlighting a Hubble image of an enormous bubble being blown into space by a super-hot, massive star. The Hubble image of the Bubble Nebula, or NGC 7635, was chosen to mark the 26th anniversary of the launch of Hubble into Earth orbit by the STS-31 space shuttle crew on April 24, 1990.
What kind of star can create a bubble like that? Although BD+60°2522 is around two million years old, the surrounding nebula is apparently only about 40,000 years old. The bubble is expected to be formed as a shock front where the stellar wind meets interstellar material at supersonic speeds. The wind from BD+60°2522 is travelling outwards at 1,800 – 2,500 km/s, causing the star to lose over a millionth of the mass of the sun every year. The effective temperature of the star is 37,500 K (the effective temperature of our sun is around 5780 K!).
BD+60°2522, the seething star forming this nebula is 45 times more massive than our sun. Gas on the star gets so hot that it escapes away into space as a “stellar wind” moving at over 4 million miles per hour. This outflow sweeps up the cold, interstellar gas in front of it, forming the outer edge of the bubble much like a snowplow piles up snow in front of it as it moves forward.
The gases heated to varying temperatures emit different colors: oxygen is hot enough to emit blue light in the bubble near the star, while the cooler pillars are yellow from the combined light of hydrogen and nitrogen.
Source: hubblesite.org, NASA’s YouTube channel.