This image of Caldwell 11 was captured by me from my driveway in the hills of NC using a SW Esprit 120ED telescope and ASI071MC cooled to 20f w/Radian Ultra Quad-Band filter, riding a SW EQ6r Pro mount.  402 3-minute exposures captured via APT and manually processed in Pixinsight combined to bring this image to life reflecting its dominant HII emmissions in a SHO palette. I do hope you enjoy this as much as I do.

From the Internet:

NGC 7635, also known as the Bubble Nebula, Sharpless 162, or Caldwell 11, is an H II region emission nebula in the constellation Cassiopeia. It lies close to the direction of the open cluster Messier 52, also in this image. The "bubble" is created by the stellar wind from a massive hot, 8.7 magnitude young central star, SAO 20575 (BD+60°2522). The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow.   A long time ago, the star began blowing a hole in the surrounding gas and dust of Caldwell 11 through radiation pressure to form the bubble shape, which has grown over time.

This image shows a bubble floating serenely against a muddy reddish celestial background, forming object number 11 in the Caldwell catalog, more popularly known as the Bubble Nebula. Caldwell 11 is an emission nebula — a cloud of gas that gives off its own light — and actually includes not just the bubble but all the gas surrounding it as well. Stars shine throughout the field like specks of glitter, adding to the nebula’s stunning composition.  The M51 globular cluster known as the Cassiopeia Salt & Pepper cluster is located to the left of the Bubble nebulosity.

Caldwell 11’s bubble can be thought of as a continuously receding shock wave emanating from that star, which is positioned in the lower right of the bubble. The star’s stellar wind reaches 4 million miles per hour, carrying particles from the star’s surface and helping to propel the “shock wave” outward. The result ends up looking something like a planetary nebula, in which a star’s outer layers expand outward, but it is in fact gas and dust from the surrounding nebula that’s being pushed away from the star. This surrounding material is more dense to one side of the star, so the stellar wind meets greater resistance and progresses less in that direction, offsetting the central star from the geometric center of the bubble.

Caldwell 11 was discovered by astronomer William Herschel in November of 1787. This was a busy year for Herschel, during which he also found two moons orbiting Uranus: Titania and Oberon. Just a few years prior, he had discovered the planet Uranus itself and had subsequently been appointed Court Astronomer by King George III, undoubtedly a perk to go along with his sudden fame. Herschel made significant progress in the world of astronomy, identifying and cataloging 2,500 nebulae and star clusters during his career — among them many of the objects later collected in the Caldwell catalog.

Although a challenge to observe or photograph, it really is a lovely object as it contains a bubble in the nebula. This is created by a star 40 times the size of our sun in the middle of the bubble blowing out a stellar wind on its way to going supernova.  The best time to view or photograph Caldwell 11 from the Northern Hemisphere is in the autumn. Those in the Southern Hemisphere will need to be near the equator to see it, and should look low in the northern sky during spring. The 10th-magnitude nebula resides in the constellation Cassiopeia, which is recognizable by its characteristic connect-the-dots version of a large “W” in the sky. To best observe it, use a large telescope equipped with a light-pollution filter to increase the contrast and spot some of the finer features of this nebula, which appears as a dim, diffuse, oval patch of light.