Sh2-170 in Cassiopeia




© Velimir Popov & Emil Ivanov 2020
Size: 1800 px
Located close to the much more prominent NGC 7822, Sh2-170 is not a common imaging target out there these days. Тhis small Sharpless object is an H II region located on the Perseus Arm at about 2300 parsecs (about 7500 light years) away, near the edge of a large superbubble originating from the combined action of the stellar wind of the stellar association Cassiopeia OB5. The star responsible for ionizing its gases is known by the abbreviation BD + 63 2093; it is a main sequence star with spectral class O9V, belonging to the small and young open cluster Stock 18. The edges of the ionized region are mostly blurred, indicating a lower density on the periphery, except for the south-eastern side; the ionizing star is located near the center, on the front edge of a small isolated molecular cloud. It is believed that 40% of the mass of the complex is made up of monoatomic neutral hydrogen (HI), located beyond the ionization front. The infrared radiation source IRAS 00001 + 6417, observable in the direction of the nebula, corresponds to a molecular cloud with CO emissions probably located at a greater distance, around 4600 parsecs, although the Avedisova Catalog indicates it as related to Sh2-170.

Image details:


Center of field RA 00:01:34 (h:m:s)
Center of field DE +64:38:04 (deg:m:s)
Size 35.2 x 26.2 (arcmin)
Pixel scale: 1.17 (arcsec/pixel)
Orientation: Up is 182 degrees E of N
Charts and image details obtained from
Optic(s): ASA 12" Astrograph @ f/6.3 (Newton)
Mount: ASA DDM85 Standard
Camera: SBIG STL 11000 M
Filters: Luminance, Red, Green, Blue, Astronomik filters Ha, OIII Baader filters
Dates/Times: 28,29 Nov.; 2,3,4 Dec. 2011
Location: IRIDA Observatory, BG, longitude: E 24 44' 18", latitude: N 41 41' 42"
Exp. Details: RGB:3x10 min, Ha:22x30min,SII:18x30min; OIII:20x30min. Bin 1 Total exp.time: 1890 min (31:30 hrs)
More details: Dark and flat frames reduction
Processing: PixInsight / PS
Copyright: Velimir Popov and Emil Ivanov 2020. All Rights Reserved
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