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

H II region An H II region or HII 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 hundred ...

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 emissio ...

in the constellation Cassiopeia. It lies close to the

open cluster An open cluster is a type of star cluster made of up 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, is an open cluster of stars in the highly northern constellation of Cassiopeia (constellation), Cassiopeia. It was discovered by Charles Messier on 1774. It can be seen from Earth under light pollution, ...

. The "bubble" is created by the

stellar wind A stellar wind is a flow of gas ejected from the 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 spherically symmetric. D ...

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 an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

, 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, the density and size of which 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 (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline H ...

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

Notes

References

* * * * * *

External links

NGC7635 The Bubble Nebula
*
Bubble Nebula at Constellation Guide
* {{Portal bar, Astronomy, Stars, Outer space Astronomical objects discovered in 1787 011b Cassiopeia (constellation) Emission nebulae H II regions 7635 Sharpless objects

Amateur observation

See also

Notes

References

External links