Description
Of The Region
[
Intro ] [ Description of Region
] | [ Nebula Case Study ] | [NGC
2024] | [Reflection Nebulae]
Astronomy
| Topics
IC 434is
classed as an emission nebula,
and consists of a bright red strip of excited hydrogen gas. This gas is
very transparent to UV and visible light, so much so that, in high resolution
photos of the area, background galaxies are visible through it. IC434 is
powered by the blue star Sigma Orionis (see diagram), which is 1600 light
years from Earth. The material of IC 434 forms an incomplete sphere around
Sigma Orionis, although this cannot be seen on the photograph because this
concentrates on the Horsehead, rather than the whole of the Orion complex.
Zeta
Orionis, the
left star in the "belt of Orion", is another very obvious part of the picture
(it is the glare from this star that makes the Horsehead so difficult to
see visually). Zeta, however, is a foreground object, being only 1100 light
years from Earth (and therefore much closer to us than the nebula).
The light given out by Zeta is reflected by dust surrounding it and gives
the blueish tinge to the north (top) end of IC 434.
NGC 2024:The
extremely dense (relative to an "average" region of interstellar space
!) nebula NGC 2024 is to the left of Zeta Orionis.
It is a dusty
HII region. It
is thought that the star, or stars, which power it are embedded deep inside
the nebula. It is also thought to be a stellar birthplace, but since
it is so dense it is difficult to ascertain whether or not this is true.
IC 431
and IC432
are small blue
reflection nebulae, as are IC 435 and NGC 2023. Reflection
nebulae are produced when clouds of dust reflect the light from a nearby
star.
Back
To The Top