TYPES OF NEBULAE
By Raahil Ashraf VIII-A
NEBULAE
 To start
 A nebula is a giant cloud of dust and gas in space. Some nebulae (more than one
nebula) come from the gas and dust thrown out by the explosion of a dying star,
such as a supernova. Other nebulae are regions where new stars are beginning to
form.
TYPES OF NEBULAE
Planetary
nebulae
 Nebulae are classified into one of two categories including
extragalactic and galactic. Practically nothing is known
about extragalactic nebulae, so the focus will be on
galactic. Galactic nebulae can be further divided into either
planetary or diffuse nebulae. Planetary (regular) nebulae
have a distinct shape, where diffuse nebulae are irregular.
Diffuse Nebulae are then broken down into dark and
luminous. This sounds exactly like it is. Dark nebulae do
not emit as much light as the luminous, so they appear as
dark, irregular blotches in the sky. Luminous nebulae can
either be emission or reflection types. Emission can then
be categorized as supernova remnants or H II regions.
PLANETARY NEBULAE
 When a star dies, it doesn't explode into a supernova
or collapse into a black hole. Instead, it gently sheds
its outer layers, which form a beautiful cloud called a
“planetary nebula”, while the dying star's core
becomes a white dwarf.
DIFFUSE NEBULAE
 Diffuse nebulae are named for their widespread,
fairly thin regions of gas and dust. Diffuse nebulae,
like the Orion Nebula, can be regions of star
formations if they are large enough. Once all the gas
and ions have been used in a diffuse nebula, a group
of young, hot stars remains in an open star cluster.
Diffuse nebula can be classified as dark or luminous.
DARK NEBULAE
 Dark nebulae are dense regions in space that do not
emit light. They look like big black opaque splotches
surrounded by the starry night. Dark Nebulae are so
dense with dust and particles that no light passes
through them. They tend to have irregular shapes,
with no definable outer edges. These vast clouds are
mostly composed of molecular hydrogen.
LUMINOUS NEBULAE
 Luminous nebulae are made
bright by radiation from stars in
the vicinity.
REFLECTION NEBULAE
 Reflection nebula are clouds of interstellar dust which
might reflect the light of a nearby star or stars. The
energy from the nearby stars is insufficient to ionize
the gas of the nebula to create an emission nebula,
but is enough to give sufficient scattering to make
the dust visible.
EMISSION NEBULAE
 An emission nebula is a cloud of high temperature
gas. Within this type of nebula, a star energizes the
atoms in the cloud with ultraviolet radiation. The
process is similar to that of a neon light. This causes
the nebula to glow.
SUPERNOVA NEBULAE
 When the pressure drops low enough in a massive
star, gravity suddenly takes over and the star
collapses in just seconds. This collapse produces the
explosion we call a supernova. Supernovae are so
powerful they create new atomic nuclei.
HII REGIONS NEBULAE
 HII regions are emission nebulae created when
young, massive stars ionise nearby gas clouds with
high-energy UV radiation.
THANK YOU
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