Nebulae and Star Clusters (Important Facts) {Part-4}

A NEBULAE IS A CLOUD OF DUST AND GAS inside a galaxy. Nebulae become visible if the gas glows, or if the cloud reflects starlight or obscures light from more distant objects.

Sky Nebulae

1.Emission nebulae shine because their gas emits light when it is stimulated by radiation from hot young stars.

Emission nebula LHA 120-N55 (Large Magellanic Cloud

2.Reflection nebulae shine because their dust reflects light from stars in or around the nebulae.

Reflection Nebulae

Messier 78: a reflection nebula in Orion

3.Dark nebulae appear as silhouettes because they block out light from shining nebulae or stars behind them.

The dark nebula LDN 483

Two types of nebula are associated with dying stars:
(i) Planetary Nebulae:It is a gas shell drifting away from a dying Stellar Core.

Bipolar planetary nebula NGC 6537

(ii)Supernova Remnants:It is a gas shell moving away from a Stellar Core at a great speed following a violent explosion called Supernova.

The Vela Supernova Remnant

Stars are often found in a group Known as Clusters.

The star cluster Messier 47

1.Open clusters are loose groups of a few thousand young stars that were born from the same cloud and are drifting apart.

The Wild Duck(Open Cluster)

2.Globular clusters are densely packed,roughly spherical groups of hundreds of thousands of older stars.

Globular Cluster NGC 6397

Here are some of the images of nebulae down below:-

1.Thor’s Helmet Nebula

2.The Helix Nebula

3.The Pencil Nebula

4.The Horsehead Nebula

5.The Eagle Nebula

6.The Crab Nebula