Many people have heard of red giant stars and might even be able to name a few but how many people know about their cousin blue giant stars?
Blue giants are massive, hot and extremely bright. Move over red giants and make way for the blue giant.
If people have ever seen a propane gas flame compared to a flame on in a wood fire pit then they know where the blue color for blue giants comes from.
The hotter the flame the bluer it gets. Blue giants are typically known as some of the hottest objects in the galaxy.
Our sun, a yellow star, generally burns at a temperature of 6000K (that’s Kelvins!) which is an average star temperature.
In comparison, blue giants burn at a temperature of roughly 20,000K – 24,000K. That is three to four times hotter than our star.
This extreme heat and color create a lot of light.
Blue giants are some of the brightest stars in the sky and are also some of the most recognizable stars to the naked eye.
Three of the top five brightest stars after our sun are blue giant stars.
The Bigger They Are…
Yellow stars like our sun are some of the most common stars in the universe due to their stability.
Stars like our sun have very stable makeup which will allow them to live for ten billion years or more.
In contrast, blue giant stars are much rarer and live for much shorter periods than stars like our sun.
Blue giant stars are extremely massive, extremely hot and extremely bright due to their furious rate and intensity at which they burn fuel.
The mass plus the burn rate creates the star’s recognizable brightness in the sky.
This also means that they will not live for very long compared to other stars in the galaxy.
How Long Will they live?
The estimated lifespan of blue giant stars is in the millions rather than billions of years.
The stars will burn off all of their fuel extremely quickly before collapsing.
The amount of mass being burned in a relatively short period means that at the end of their lifespan most giant blue stars will implode and form black holes.
Blue giant stars do not go through an established life pattern that other more stable stars go through.
They appear quickly on the galactic stage and live violently like a top spinning out of control.
Their color remains relatively the same, as does their size so aging them can be difficult before they vanish from the night sky.
The spectacular super-giant blue stars will have so much mass and so much energy that they usually will simply explode into massive supernovas that can be seen from Earth.
The inherent instability of blue giant stars makes it so their deaths will not be as simple or quiet like many other stars in the galaxy.
From their size to their brightness and heat blue giant stars push the physics of stars to the limit.
Even in death, these stars will continue into a new phase of intensity either making a terrifying black hole or a spectacular supernova.
Basking in the Blue Light
Are there humans or blue light adaptive creatures living on some distant planet orbiting one of these monsters? Scientists think probably not.
It takes a lot of time and factors to create a solar system like ours and blue giant stars usually do not live long enough to allow solar systems to form.
What people think of as a classic solar system, one that is close to Earth’s, takes billions of years to form.
Blue giant stars might live to be about half a billion years old at their oldest.
This leaves blue stars isolated in space usually with some remnant dust or gas but no fully formed planets, especially none that scientists think could support any life.
Even if these solar systems had time to form, blue giant stars are so volatile that they probably could not form anyways.
With powerful hot solar flares and a stiff solar wind, it would not allow for the slow coagulation of dust that is needed for planets to form.
There are too much energy and instability in a blue giant star’s vicinity to create a stable environment needed for a solar system to grow.
Even if life did evolve rapidly around a blue giant star they would be nothing like the life that is found on Earth.
They would have evolved to see on a blue light spectrum while all of our life sees on the yellow end of the spectrum.
They would also have had to evolve under stiff solar winds with the possibility of powerful energy ejections from the star that could wipe them out at any time.
Classifying the Giants
Stars are classified on a seven-level scale. Many people learn the classification system as Oh Be A Fine Girl Kiss Me when they are in school. O, B, A, G, K, M.
The scale goes down from heat and intensity so O class stars are generally the hottest and M class stars being the coolest.
The sun is a G class star and lies almost right in the middle of the scale. Blue giant stars, as hot and bright as they are, usually fall at the top of the scale in the OB range.
The largest and hottest of the blue giants will be O class with the rest falling in the B class.
In many ways, red giants and blue giants are opposites from each other.
They are both massive stars at different points in their lifespans but red giants are much cooler.
They are dormant and fall farther down on the stellar scale than blue giants which are way hotter and brighter and more energetic.
A blue giant is not a classification in of itself but rather a description of the star’s general appearance and qualities.
Likewise, the red giant is also not a classification but a description of the star’s characteristics in a more unofficial way.
The Famous Giants
Due to their unique color and their extreme luminosity, blue giant stars are extremely recognizable to star-gazers and average people alike.
Blue giant stars also make up a good portion of recognizable constellations. Their constant brightness makes them easy to spot from all around the world in all kinds of conditions.
Sirius is the brightest star in the sky and is a blue star with an intrinsic brightness twenty times that of our sun.
Sirius is also one of the closet stars to Earth which enhances its brightness.
This combination makes it so that Sirius is one of the oldest known stars an easily recognizable feature in any sky, no matter how dark out it is.
Vega is another blue giant star that is easily seen with the naked eye. It is part of the constellation Lyra and is usually visible in the northern sky.
Vega is twice as large as the sun, twice as young and is burning fuel at twice the rate.
Lastly, Rigel is another super famous blue giant star which is the main feature in the constellation Orion.
Rigel is roughly 860 lightyears from Earth making it much farther than the other stars mentioned here.
It is estimated to be dozens of times larger than the sun and thousands of times brighter and is considered not just a blue giant star but a supermassive blue giant star.
These are some of the most famous stars in the sky and have been staples in human constellations.
In the distant past, in the present and will continue to be stable sources of light in the future.
Picking Them Out in a Crowd
Luckily, despite their relative rarity on the galactic stage blue giant stars are fairly easy to spot and many are visible to the naked eye.
One can stare up on any given night and pick out the bluish-white stars from the yellow, orange and red ones without much coaching.
Blue giants are some of the brightest stars in the sky and they have a characteristic twinkle to them.
It is debatable whether or not the twinkling or shining feature of these blue stars is due to their blue color.
Which human eyes do not focus on very well, or the energetic nature of the stars themselves.
Outside on a relatively night, a quick scan of the night sky will reveal many blue giant stars that outshine many of their closer, yellow neighbors.
People know these stars from their prominent position in the sky and history.
They are so easily seen that people have been looking at them since the beginning of time.
They anchor our constellations, have been used for navigation and their names are widely known.
As people’s knowledge and curiosity about stars in the galaxy grew so did their interest in these unique features in the night sky.
They learned that they are hot, bright, violent, short-lived and put the sun to shame in almost every way.
They create hostile space environments in life and death and leave humanity wondering about the nature and power of the universe.