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Name / Constellation

SH2-185

Other: vdB 5; IC 59/IC 63

Cas

Coordinates AR: 00h 56m 54s - Dec: 60° 45′ 53″
Optics Takahashi FSQ 106N APO Fluorite F5 - 60/220 guiding refractor
Camera-Mount SBIG STF8300M - Orion StarShot Guider - 10Micron GM2000 QCI Mount
Filters Baader Halpha - LRGB
Exposure
  • Halpha
  • Luminance
  • Red
  • Green
  • Blue
  • 22 x 900 sec - 5 hours 30 min
  • 16 x 900 sec - 4 hours
  • 6 x 600 sec - 60 min
  • 6 x 600 sec - 60 min
  • 6 x 600 sec - 60min
  • UNBINNED
  • UNBINNED
  • BINNING 2X2
  • BINNING 2X2
  • BINNING 2X2
Location / Date Promiod (Valle D'Aosta-Italy) "TLP" Remote Observatory - 04 oct (Ha) / 05 oct (RGB) / 07 oct (Lum) 2018
Seeing 2 -3" @ 2.1 arcosec/pixel unbinned
Note  
Acquisition MaxIm DL - CCD Autopilot 5
Processing Adobe Photoshop CS6 -
Comment

Sh2-185 is an emission and reflection nebula, visible in the Cassiopea constellation; it consists of two nebulous regions distinct from the different characteristics of each other. Its position is easily identified thanks to the fact that it surrounds the brilliant star γ Cassiopeiae, a star well known for being the prototype of the γ Cassiopeiae variables, belonging to a class of young and very hot stars; the bright nebulous part is particularly found in the northeast direction with respect to the star, where there are two nebulous known as IC 59 and IC 63. In the photographs the reddish color of the ionized gas mixed with the bluish of the powders which shine by reflection of the blue light of the star.
Its observation is possible especially from the northern hemisphere regions, due to the high northern declination; in the evening sky it reaches its peak in the autumn months, between October and December. From the southern hemisphere it is possible to observe it only from the subtropical regions up to the equator.
Sh-2 185 consists of a partly well-lit system of clouds, located at the same distance as γ Cassiopeiae; the brightest sections are the two nebulae cataloged in the Index Catalog: IC 63, the southernmost, shows an obvious structure with filaments of gas, with optical emissions dominated by the red color, while IC 59, in the north, appears as a cloud with a color that tends towards blue and has no organized structure. In particular, IC 63 consists of a region of ionized hydrogen and shows clear signs of photolysis. This phenomenon is very evident above all in IC 59, while in IC 63 the presence of strong ultraviolet radiation suggests the formation of a zone of neutral hydrogen through the dissociation of molecular hydrogen. A study conducted in 1997 highlights how probably the two nebulae are not exactly at the same distance from γ Cassiopeiae: in particular, IC 63 appears directly connected to the star, while IC 59 is slightly further away; this would explain the differences between the two nebulae. Moreover, while the photolysis phenomena appear to be completely terminated in IC 59, in the second cloud they would still be in place, albeit at very low levels.
In the direction of the nebula region we can also observe the IRAS 00556 + 6048 source, which, however, would be placed at a greater distance than the nebulae; also this source shows signs of presence of a region H I and the lack of emissions in the radio continuum would suggest that also in this region there are evidences of photolysis by the radiation of a star.