dark nebula
Dark Nebula
Nebulas are glowing clouds of dust
and gases which are present in this vast multiverse ....
Unlike other nebulas which are
luminous there are nebulas which are dark and completely opaque known as
absorption nebula or dark nebula...
A dark nebula is a
type of nebula that is so dense that it conceals the light from celestial
objects behind it, such as background stars and emission or reflection nebula.
The extinction of the light is caused by dust molecules forming dense clouds.
Dark nebulas are generally coated
with frozen carbon monoxide and nitrogen, which effectively block the passage
of light at visible wavelengths. Also present are molecular hydrogen, atomic
helium, C18O (CO with oxygen as the 18O isotope), CS, NH3
(ammonia), H2CO (formaldehyde), c-C3H2
(cyclopropenylidene) and a molecular ion N2H+
(diazenylium), all of which are relatively transparent. Due to presence of
these gases these giant clouds are so dense and opaque.
The form of such dark clouds is very
irregular: they have no clearly defined outer boundaries sometimes take on
convoluted serpentine shapes.Some of these dark nebulas are..Coalsack Nebula, Cone
Nebula, Dark Doodad Nebula, Dark Horse Nebula, Horsehead Nebula, Pipe Nebula,
Snake Nebula. The largest dark nebulae are visible to the naked eye,
appearing as dark patches against the brighter background of the Milky Way like
the Coalsack Nebula and the Great Rift.
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