Nebulae represent clouds of gas and dust which appear as hazy or fuzzy objects when viewed through a telescope and are
characterized as one of four types (emission, planetary, reflection or dark). Emission nebulae, such as the Lagoon
nebula (M8), simply glow, for example, with a stunning shade of red. Planetary nebulae appear as small greenish disks
through a telescope, thus emulating the planets Uranus and Neptune, as a result of gas masses being thrown off by dying
stars (ex. M27, Dumbbell nebula) or represent supernova remnants (ex. M1, Crab nebula). In contrast, reflection nebulae
are characterized with gas surrounding young stars which reflect the stellar light (ex. M45, Pleiades) and, thus, yield
beautiful images of nebulosity. Finally, dark nebulae are detectable and studied only using parts other than the visible
spectrum and are believed to be associated with the formation of stars (ex. M16 in Serpens).
Note: Two very impressive and large areas of emission nebulosity in Cassiopeia are IC 1805 (Heart Nebula) and IC 1848 (Soul Nebula). The northeastern section of IC 1805 is denoted as IC 1795 and represents an area of active star formation. IC 1795 lies at a distance of about 6,500 light-years away and spans another 55 light-years in diameter. The brightest section of IC 1795 indicated by the image below is catalogued separately as NGC 896. The stars behind the hydrogen ionization and excitation of IC 1795 have yet to be identified and are presumed to be obstructed by interstellar dust and consequent absorption (the only O-type star discovered so far is BD +61° 411). An image of IC 1795 by WISE involving the infrared portion of the spectrum revealed several young stars which are a few million years old (see here). IC 1795 is also recognized as being a very strong source of radio emissions (see Aikman and Macrae).
Please click on the image below to display in higher resolution (1200 x 950)
NGC 896, Ced 6, LBN 645, CTB 9
RA / Dec:
02h 25m 48s /
61° 58' 48"
12' x 12'
Nov 04-05, 2011
19:20 - 02:40 UT+2
AP 305/f3.8 Riccardi-Honders
AP 1200GTO GEM
Baader 7nm H-a
SBIG LRGB filters
1.25" per pixel