Sharpless 2-170, also known by the common name theLittle Rosette Nebula is anemission nebula in the constellationCassiopeia.[5]
It was discovered byStewart Sharpless in the late 1950s, and its discovery published in 1959. It is named after the larger, much more well knownRosette Nebula.[4] It is located in thePerseus Arm of theMilky Way galaxy. Although being a separate nebula, it is considered as the dot in the Question Mark Nebula, as an extension ofNGC 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, andSIMBAD labels it as a G5 star.[9] The nebula contains a total of 71 variable stars.[10]
Sh 2-170 has a magnitude of about 6.5. It is best viewed with ahydrogen-alpha filter. Most of the nebula is faint enough that it requires a longer exposure time to be visible to cameras.[11]
