From: <maupperl@gmail.com>

Date: December 12, 2013 10:12:09 AM MST

To: <Astro_IIDC@yahoogroups.com>

Subject: RE: XMas Themed Print Notes

Let's try that again in better English:

Different Nebula In This Image

Background: Core area of Messier 42 (The Orion Nebula) centered on Trapezium

Top Row (L to R):  NGC 6992 (Veil Nebula East - Witches' Broom North) , Messier 1 (Crab Nebula), NGC 7635 (Bubble Nebula)

Middle Row (L to R): Messier 27 (DumbBell Nebula) , NGC 2438 (a ring Nebula in Messier 46) NGC 2392 (Eskimo Nebula) , Messier 57 (Ring Nebula)

Bottom Row (L to R): NGC 1973 (Running Man Nebula), IC 434 (Horse Head Nebula) , NGC 6995 (Veil Nebula East - Witches' Broom South)

Five Nebula Types

EMISSION NEBULA = (Messier 42 Orion Nebula, NGC 7635 Bubble Nebula)

An emission nebula is a cloud of high temperature gas in which the atoms are energized with ultraviolet light by a nearby star and emit radiation until they fall back down to lower energy states. These nebulae fluoresce much in the same way as a neon light does. Emission nebulae are normally a space of consistent and ongoing star creation. The red is produced by hydrogen (H-alpha), while the blue and green primarily arise from oxygen (OII and OIII, respectively).

REFLECTION NEBULA = (NGC 1973 Running Man Nebula)

A reflection nebula is usually just clouds of dust and gas that reflect nearby starlight instead of making their own. These nebula are often blue because blue is more efficient for scattering light, reflection nebulae also produce many stars and are commonly found close to or melded with emission nebulae.

DARK NEBULA  = (IC 434 Horse Head Nebula, dark half of M42 Orion Nebula)

A dark nebula is physically very similar to a reflection nebula and the only reason they appear any different is because the orientation of the light source, the nebula, and earth. Essentially all that a dark nebula is doing is blocking out the light of everything behind it.

PLANETARY NEBULA  = (Messier 1 Crab Nebula,  Messier 27 DumbBell Nebula, NGC 2438 a ring Nebula in Messier 46, Messier 57 Ring Nebula, NGC 2392 Eskimo Nebula)

Planetary nebula, have nothing to do with planets, instead, they are the gas remnants thrown out by some stars near the end of their lifespan. Basically they are stellar "burps".

SUPERNOVA REMNANTS =  (NGC 6992 and NGC 6995 Veil Nebula East - Witches' Broom North and South)

A supernova is formed when a large star explodes at the end of its lifespan. A supernova remnant is the part of the star blown off into space. The red is produced by hydrogen (H-alpha), while the green primarily arise from oxygen (OIII).