Star Classification The Sun is a as a G2V type star, a yellow dwarf and a main sequence star. Stars are classified by their spectra (the elements that they absorb) and their temperature. There are seven main types of stars. In order of decreasing temperature, O, B, A, F, G, K, and M. O and B stars are uncommon but very bright; M stars are common but dim.. An easy mnemonic for remembering these is: Oh be a fine guy/girl, kiss me. Hertzsprung - Russell Diagram The Hertzsprung -Russell (H-R) Diagram is a graph that plots stars color (spectral type or surface temperature) vs. its luminosity (intrinsic brightness or absolute magnitude). On it, astronomers plot stars color, temperature, luminosity, spectral type, and evolutionary stage. This diagram shows that there are 3 very different types of stars: Most stars, including the sun, are main sequence stars, fueled by nuclear fusion converting hydrogen into helium. For these stars, the hotter they are, the brighter. These stars are in the most stable part of their existence; this stage generally lasts for about 5 billion years. As stars begin to die, they become giants and supergiants (above the main sequence). These stars have depleted their hydrogen supply and are very old. The core contracts as the outer layers expand. These stars will eventually explode (becoming a planetary nebula or supernova, depending on their mass) and then become white dwarfs, neutron stars, or black holes (again depending on their mass). Smaller stars (like our Sun) eventually become faint white dwarfs (hot, white, dim stars) that are below the main sequence. These hot, shrinking stars have depleted their nuclear fuels and will eventually become cold, dark, black dwarfs.
Posted on: Sat, 14 Jun 2014 20:16:40 +0000
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