Science

[Shallara Navor Hevoda 0]

One of the most beautifull sights in space are star clusters. One souch cluster is the Pleiades, also known as "The Seven Sisters" due to the fact that only seven of the stars in the cluster can be seen with the naked eye from Earth. Yet this particular cluster containse some 3,000 stars. New stars are most likely still being born, although this has never been documented. It is theorized that new stars will continue to emerge from this nebula star nursery untill the gas is completely consumed. These infint stars apear to shine with a bluish glow. This is caused by the reflection of starlight from the nebulain wich they are embeded.

 

Starbirth begins when a shockwave fragments a nebula, which then colapses. Then the colapsing cloudcondenses into hot, young stars. Ultraviolet radiationthat is emited creates a region of high density. Gravity causes the cloud's dense region to contract more, providing materials for a new generation of stars. The chain reaction of star birth continues as the next generation of young stars produces more ultraviolet radiation, which in turn further increases the density of the remaining gas and dust in the cloud. New stars continue to form until the gas in the clous are exhausted.

 

 

Shallara N. Hevoda

[Shallara Navor Hevoda 0]

The nearest star to the Earth, apart from the Sun, is Proxima Centauri, which is 39.9 petametres (39.9 Pm = 39.9 trillion kilometres = 4.2 light years = 1.29 pc = 1.29 parsecs) away. So light from Proxima Centauri takes 4.2 years to reach Earth. If you took the French TGV, one of the fastest trains, on a trip to Proxima Centauri using its highest recorded speed (515.3 km/h), it would take you about 8.86 million years to get there!

 

This distance is typical of galaxy discs. Stars can be much closer to each other in galaxy and globular cluster centres, or much further apart in galactic halos. Between this distance and a few times this distance, there are quite a few other stars. Astronomers estimate that there are at least 70 sextillion (70×1021) stars in the known universe [1] (http://news.bbc.co.uk/2/hi/science/nature/3085885.stm). That is 70 000 000 000 000 000 000 000, or 230 billion times as much as the 300 billion in our own Milky Way.

 

Globular clusters are usually composed of hundreds of thousands of old stars, similar to the bulge of a spiral galaxy but confined to a volume of only a few cubic parsecs. Globular clusters are fairly numerous; there are about 150 currently known globulars of the Milky Way (with perhaps 10-20 more undiscovered), and larger galaxies like Andromeda have more (Andromeda may have as many as 500). Some giant elliptical galaxies (e.g., M87) may have as many as 10 thousand globular clusters. These globular clusters orbit the galaxy out to large radii, 100 kiloparsecs or more.

 

I hope I have answered your question.

Shallara