Types of Star

Our closest star the Sun, provides just the right amount of heat and light energy to provide life on our planet, and it is considered an “average” star- but what about the billions of other stars out there? From Pulsars to Black Holes, there are many fascinating types of stars.

Our Average Sun

A good place to start with examining the various types of stars would be with the one most familiar to us, the Sun. The Sun is a Main Sequence Star, a classification given to “average” and “normal” stars that fall under certain criteria. Sort of “middle of the road” stars, Main Sequence Stars have an average size and luminosity, and variations from this starting point give us the other star types. This based on a curve called the Hertzsprung-Russell diagram, which classifies stars based on their temperature as well as size and luminosity.

Going up to larger stars enters the “Giant Star” category, with Hyper Giants, Super Giants and Bright Giants on the list, in order of largest to smallest. Sol, our Sun, as all Main Sequence Stars is considered a “Dwarf” star, as are all stars lower down the scale.

There are Subdwarfs, Red Dwarfs, White Dwarfs, Brown Dwarfs and, theoretically, Black Dwarfs, although the universe is not yet old enough to have produced one of those.

From Giant to Dwarf

To better understand the Giants and Dwarfs of the universe, a brief examination of a star life cycle is required, starting from a Main Sequence Star, using the Sun as an example. When the Sun, in about 6 billion years, stops generating energy through hydrogen fusion it will begin to expand, becoming a Giant star. This expansion process continues until the gaseous surface of the Sun dissipates away, leaving the core. The core is the White Dwarf.

This is all in reference to stars like the Earth’s Sun, but there are many, many different variations on the same theme. Here are a few examples:

Black Hole

Immediately capturing the imagination of writers and filmmakers when first discovered, a Black Hole is a region of space where a star used to be. It is believed that when a star achieves enough mass it collapses inward, possibly after first exploding as a Supernova, creating a region of space that exists outside the known universe. No matter or energy can escape a black hole. The lack of emitting electromagnetic radiation makes it invisible, hence the name.

Binary Star

A Binary Star is actually a two-star system; two stars orbit each other around their centre mass.

Blue Straggler

The theory behind a Blue Straggler star is that it is a binary star in the process of merging to become one star. A Blue Straggler is so named because it is hotter and bluer than other stars with the same luminosity, and also is found off the normal curve of proposed stellar evolution.

Neutron Star

Another possible outcome from a Supernova, a Neutron Star is what a star becomes at the end of its life cycle if it does not have enough mass to become a Black Hole.

Magnetar

This is a Neutron Star with an extremely powerful and active magnetic field.

Pulsar

Another type of Neutron Star, a Pulsar (short for Pulsating Star) emits radio waves with precise regularity, and the first one discovered was code named LGM-1, as scientists wondered if it was a beacon from Little Green Men.

Final Thoughts

The vast variety of star types has begun to fall into regular classification, but there always seems to be a new discovery that leaves scientists scratching their heads. With the infinite vastness of space, there likely always will be.