NGC 7635, also known as the Bubble Nebula, Sharpless 162, or Caldwell 11, is an

H II region An H II region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light year ...

emission nebula An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission n ...

in the constellation

Cassiopeia Cassiopeia or Cassiopea may refer to: Greek mythology * Cassiopeia (mother of Andromeda), queen of Aethiopia and mother of Andromeda * Cassiopeia (wife of Phoenix), wife of Phoenix, king of Phoenicia * Cassiopeia, wife of Epaphus, king of Egy ...

. It lies close to the

open cluster An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

Messier 52 Messier 52 or M52, also known as NGC 7654 or the Scorpion Cluster, is an open cluster of stars in the highly northern constellation of Cassiopeia (constellation), Cassiopeia. It was discovered by Charles Messier in 1774. It can be seen from Earth ...

. The "bubble" is created by the

stellar wind A stellar wind is a flow of gas ejected from the stellar atmosphere, upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spheri ...

from a massive hot, 8.7

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

young central

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

, SAO 20575 ( BD+60°2522). The nebula is near a giant

molecular cloud A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, ...

which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow. It was discovered in November 1787 by

William Herschel Frederick William Herschel ( ; ; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover ...

. The star BD+60°2522 is thought to have a mass of about .

Amateur observation

With an telescope, the nebula is visible as an extremely faint and large shell around the star. The nearby 7th magnitude star on the west hinders observation, but one can view the nebula using

averted vision Averted vision is a technique for viewing faint objects which uses peripheral vision. It involves not looking directly at the object, but looking a little off to the side, while continuing to concentrate on the object. This subject is discussed in ...

. Using a scope, one can see that the faint nebula is irregular, being elongated in the north south direction.

Notes

References

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External links

NGC7635 The Bubble Nebula
*
Bubble Nebula at Constellation Guide
* {{sky, 23, 20, 48.3, +, 61, 12, 06, 7100 178711?? 011b Cassiopeia (constellation) H II regions NGC objects Sharpless objects

Amateur observation

See also

Notes

References

External links