The Bubble Nebula is a glowing cloud of stars, gas, and dust located some 11,300 light years away toward the constellation Cassiopeia. (The Bubble Nebula is also designated as NGC 7635.) The nebula surrounds a hot star roughly 20 times more massive than the Sun, which is visible near the right-hand edge of the image. Ultraviolet light from the star causes the gas to glow through a process known as fluorescence, and winds of material blown out from the star give the nebula its characteristic shape. The nebula is some 10 light years across.

The Bubble Nebula is an example of a massive star with an extremely strong solar wind embedded inside a large gas cloud. This wind is moving at 2000 km per second (4 million miles per hour)  and has carved out a large bubble 7 light years in diameter within the cloud. The wind slows as it hits the much denser gas cloud, creating the surface of the bubble. The star responsible is the brightest star within the bubble (the star with diffraction spikes in this photo) - BD602522 also known as SAO20575. This blue star is 40 times more massive than the sun but due to it's distance of 7100 light years, its apparent magnitude is just 8.7. The star is not at the center of the bubble. This is because the surrounding gas is not uniform and is much denser at the top left - which slows down the solar wind much sooner. At the top left of the gas cloud you can just make out some dense clumps or columns of gas. These are similar to the famous columns in the Eagle Nebula, but they are not being eroded as fast. The whole nebula is glowing due to the intense ultra violet radiation from the central star.

This image was captured on 11th August 2010. 10 x 5 minute images at ISO 1600 were taken with a Canon 40D DSLR and Stellarview 102ED Refractor. Captured in Nebulosity and processed in Images Plus and Photoshop. The above image cropped and enlarged.

Open cluster M52 is one of the original discoveries of Charles Messier who catologed it on September 7, 1774 when the comet of that year came close to it.

Amateur Astronomers like myself can see M52 as a nebulous patch in good binoculars or finder scopes. In 4-inch telescopes, it appears as a fine, rich compressed cluster of faint stars, often described as of fan or "V" shape; the bright yellow star is to the SW edge. John Mallas noted "a needle-shaped inner region inside a half-circle."

M52 can be found quite easily by extending the line from Alpha over Beta Cassiopeiae by 6 1/2 degrees to the NW to 5th mag 4 Cassiopeiae; M52 is roughly 1 degree south and slightly west of this star. Just immediately south of M52 is the little conspicuous open cluster Czernik 43 (Cz 43), which is visible in larger telescopes only.

Images copyright K.Grice 2010