Nebulae are both the cradle and grave for stars. 💫 engineering
. Much of this is composed of gas, with about 75% hydrogen and around 25% helium. The interstellar medium includes both neutral atoms and molecules and charged particles, such as ions and electrons. Normally, these particles are very spread out, with an average density of around just 1 atom per cubic centimeter.
Although this is a very low density, the total amount of matter can add up to quite a bit over the vast interstellar distances. Over time, gravitational attraction can cause this matter to coalesce into larger and larger clumps. In regions of high density, pressure from gravity may cause the gaseous material to heat up enough to ignite fusion. When this happens, new stars may be formed.However, gravitational attraction is not the only way a nebula may be formed.
called a supernova remnant nebula. These are not always visible, but may emit powerful X-ray and radio waves due to interactions with the surrounding interstellar medium. Remnant nebulaeAnother kind of nebula that is formed after the death of a low-mass star is called planetary nebulae.The word planetary is a bit misleading because these nebulae have nothing to do with the planets.
by 19th-century astronomer William Herschel, because the new objects resembled a gas giant when viewedThe matter from the outer layer becomes distributed around the dying star and causes the formation of a planetary nebula. The radiation released from the star’s expanding corethat resulted from the blast. At this time, when the core is still burning heat, it is called a white dwarf star. As the core of the planetary nebula cools, it becomes a black dwarf star.
Planetary nebulae resulting from the death of dwarf stars and supernova remnant nebula can not give rise to new stars, but interstellar molecular clouds like the Swan nebula or the Orion nebula act as active star nurseries. Most nebulae are vast, spanningkg but a nebula having size the same as of the Earth would weigh only a few pounds.Apart from supernova remnants and planetary nebulae, there are three other types of nebulae.