Sh 2-170
Sharpless 2-170, also known by the common name the Little Rosette Nebula is an emission nebula in the constellation Cassiopeia.
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. It is located in the Perseus Arm of the Milky Way galaxy. 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. 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. Some of its illumination is caused by the ionizing of gas by the star BD + 63 2093, also designated LS I +64 11. 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. The nebula contains a total of 71 variable stars.