Sh 2-170

Sharpless 2-170, Also known by the common name the Little Rosette Nebula is an emission nebula in the constellation Cassiopeia^[5].

Little Rosette Nebula

Emission nebula
H II region
Sh2-170 as seen by the Hubble Space Telescope
Observation data: epoch
Right ascension	00h 01m 29s
Declination	+64° 39' 03"
Distance	7,500[1] ly
Apparent magnitude (V)	~6.5
Apparent dimensions (V)	56' x 50'[2]
Constellation	Cassiopeia
Designations	LBN 577, Sh 2-170,[3] LBN 117.62+02.29 [4]
See also: Lists of nebulae

It was discovered by Stewart Sharpless in the late 1950s, and its discovery published in 1959. It is named after the larger, much more well known Rosette Nebula.^[4] It is located in the Perseus arm of the Milky Way. Although being a separate nebula, it is considered as the dot in the Question Mark Nebula, as an extension of NGC 7822.

The nebula contains a central star cluster, Stock 18.^[6] Stock 18, has an apparent size much smaller than the nebula's total of 56 x 50 arcminutes, with the cluster having an apparent size of just 18 arcminutes.^[7] Some of its illumination is caused by the ionizing of gas by the star BD + 63 2093, also designated LS I +64 11.^[8] There is dispute between studies as to the nature of said central star. A 1995 paper concluded the star was a O8 V type, however other papers have identified it as a O9 V type, and SIMBAD labels it as a G5 star.^[9] The nebula contains a total of 71 variable stars.^[10]

Visibility

Sh2-170 has a magnitude of about 6.5. It is best viewed with a hydrogen-alpha filter. Most of the nebula is faint enough that it requires a longer exposure time to be visible to cameras.^[11]

See also

• Rosette Nebula
• NGC 1624, the Little Cocoon Nebula