Universe Guide

O, B, A Type Stars - Blue Dwarf and Giant Stars

The colour of a star refers to the temperature and not the size. Currently, the only Blue stars that exist are giant stars and not dwarf stars. Blue stars are the hottest stars that are currently in existence. Whilst most star types have heat ranges, the O-Type star stars from 30,000K without an upper range.

Blue stars burn through their fuels at a phenomenal rate compared to the cooler red stars. Blue stars are most likely to have life spans of millions of years whereas yellow dwarf stars such as the Sun will have a time span of billions and Red Dwarf stars will have a timespan of trillions possibly.

Blue Giants, SuperGiants and HyperGiants

Blue Giants stars are the hottest types of stars that are currently around. These stars are rare compared to Red Dwarf Stars. Blue Dwarf Stars can be one of three Spectral Types, O and B and A. Their temperatures are about 10,000 Kelvin. They radiate more energy than what our Sun can produce in the same time period.

Blue Giants are one of the rarest types that you can see in the sky. The most common are the Red Dwarf stars. The earliest stars in the Universe, the quasi-stars were blue but all have now gone, they would have gone supernova thus creating the materials for the next generation of stars. Quasi-stars are many times bigger than the blue hypergiants that exist today.

There are no known exoplanets to orbit a blue star. Blue stars would not last for long allowing planets and life to gain a foothold. Planets would be tiny compared to Blue Giants and so detecting them would be difficult due to such a tiny amount of influence the planet would have. Planets have been found in orbit round Orange Giants so there's always a possibility. Orange Giants it should be noted are stable, more cooler stars than Blue giants and so provide a better environment for planets to exist.

Should a planet exist round a Blue Giant, the planet would orbit the star at a greater distance from the star than the Earth does so as to be in the Goldilocks Zone. The Goldilocks zone is where it is not too hot and not too cold for life to exist.

Blue Stragglers

Blue stars tend to be young stars because they burn and use all their fuel quicker than the cooler stars. In some star clusters, you will find blue stars referred to as blue stragglers. Blue Stragglers will look more youthful that they really are. These Blue Stragglers are vampire stars, they siphon fuel from nearby stars to make them look big and younger than the others.

List of Example Blue Giant Stars

Blue Dwarf Stars

Blue dwarf stars are stars that do not exist at the present time because the universe is far too young for Red Dwarfs to turn into them. They have been theorized to exist in the future along with black dwarf stars. They have been calculated to exist when a Red Dwarf Star has finished fusing its hydrogen and is ready to move on.

Red Dwarf stars are very fuel efficient and are very slow at converting hydrogen into helium, there are none out there so far. Proxima Centauri, our nearest star and red dwarf is expected to last long after our Sun has gone. Red Dwarf Stars are amongst the coolest stars in the universe along with brown dwarf stars. When a red dwarf star turns to blue, they become much hotter than they were when they were younger.

Calling them a Blue Dwarf is a misnomer as it doesn't mean they turn blue. It is simply the result of a significant increase in the star’s surface temperature, causing a large shift in the star’s light towards the bluer side of the electromagnetic spectrum. The blue dwarf's temperature would be comparable to the temperature of the Sun. Beyond Earthly Skies

You might see on some H.R. Diagrams where Sirius B looks like its a Blue Dwarf Star, in reality, its not, its a white dwarf star.

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