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What are Some Different Types of Stars?

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  • Written By: Michael Anissimov
  • Edited By: Bronwyn Harris
  • Last Modified Date: 16 November 2016
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Most stars fall into a categorization class called the main sequence, also known as dwarf stars. In a standard chart plotting star color against magnitude, known as the Hertzsprung-Russell diagram, the main sequence stars form a coherent curve, unlike the other categories — white dwarfs, subgiants, giants, bright giants, and supergiants. Although not usually included on the chart, black holes, which are gravitationally collapsed stars, might be considered points on the chart with zero luminosity and a spectral signature of 0° K.

The reason why the main sequence stars fall on a predictable curve is because their luminosity and spectral signatures are dictated solely by their mass, which ranges from 0.08 to about 158 solar masses. White dwarfs, stars that have exhausted their nuclear fuel, have similar spectral signatures to main sequence stars, but much less luminosity. This is because they do not fuse elements or have an ongoing source of energy — their luminosity and heat is all left-over. Over the course of billions of years, it is expected that white dwarfs will cool and become black dwarfs, or lifeless star hulks. However, no white dwarf has been around long enough for this to happen yet.

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Main sequence stars fall into several categories: brown dwarfs, with only around 0.08 solar masses, are basically oversized Jupiters with weak fusion reactions in their cores; red dwarfs are slightly hotter and more energetic, with greater mass; these are followed by yellow dwarfs, very common stars of which our Sun is an example.

When stars burn up all their nuclear fuel in the form of hydrogen, they start fusing helium. Because old stars begin to build up a solid core of fused material, the powerful gravitational forces on the core's perimeter compress together the gas layers above, accelerating fusion and increase a star's luminosity and size. Through this developmental route, dwarf stars become giants. Depending on their mass, they eventually collapse into white dwarfs, neutron stars, or black holes. The more massive stars cause supernovas, which are huge blasts of energy which escape when fusion ceases in the stellar core and the gas layers rub vigorously against another during the final collapse.

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dbuckley212
Post 4

@BigBloom

Not only that, but what we are viewing is not a current galaxy or star, but what the star may have looked like millions of years ago, since they are millions of light years away. It is possible that stars are forming on the edges of the galaxy which we could never see in our lifetime.

BigBloom
Post 3

Star constellations are often made up of more than just stars. Sometimes there is an entire galaxy or formation of stars in what appears to us to be a single component in a star formation. There could be billions of distant stars in what looks to us like one star.

Qohe1et
Post 2

Our understanding of stars has undergone many shifts over the ages, and only today are we beginning to grasp what they truly are. The observation of astronomic phenomena like black holes is taking science to placed beyond where it has ever gone, outside of the laws and confines of the space time continuum. To view the stars is to have one's head in a place that is truly beyond our ability to fully comprehend.

BostonIrish
Post 1

Star gazing is a fun and gratifying hobby that can be very helpful in understanding the universe and our small place in it. Seeing constellations and signs from many different cultures is also an interesting astrological/ psychological exercise. People project their cultural ideals and mythologies onto their opinions about star formations.

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