An Expanding Bubble in Space

A star 40 times more massive than the Sun is blowing a giant bubble of material into space. In this colorful picture, the Hubble telescope has captured a glimpse of the expanding bubble, dubbed the Bubble Nebula (NGC 7635). The beefy star [lower center] is embedded in the bright blue bubble. The stellar powerhouse is so hot that it is quickly shedding material into space. The dense gas surrounding the star is shaping the castoff material into a bubble. The bubble's surface is not smooth like a soap bubble's. Its rippled appearance is due to encounters with gases of different thickness. The nebula is 6 light-years wide and is expanding at 4 million miles per hour (7 million kilometers per hour). The nebula is 7,100 light-years from Earth in the constellation Cassiopeia.

1. What are the yellow-colored "clouds" to the right of the star?

These "clouds" are a ridge of much denser gas. The lower left portion of this ridge is the brightest because it is closest to the star. But the star's intense ultraviolet light and its strong "wind" of material is heating and eroding this area the fastest. The region between the star and the ridge reveals several loops and arcs that have never been seen before. Hubble's sharp resolution allows astronomers to examine these features in greater detail. Astronomers are uncertain about the origin of this "bubble-within-a-bubble." It may be due to a collision of two distinct winds of material. The star's intense wind may be colliding with material streaming off the ridge of gas, which the star's intense radiation is heating and eroding.

2. What are the blobs of gas in the picture's upper left corner?

Those blobs are dense clumps or fingers of gas that are being illuminated by the star's light. The blobs have not yet encountered the expanding bubble.