Stars come in many different sizes and colors. Many questions may arise when considering how this has happened. One of those subjects is determining what the smallest star is.
As many of you reading this article know, stars are considered colossal. All stars are many times larger than Earth.
You may have wondered, what is the smallest star in the universe? Is there one that is truly tiny to behold? Or are they all colossal in terms of size?
If you’ve found yourself asking these questions, don’t worry, you’re not alone.
We will be taking a closer look at the smallest star known. In addition to this, we’ll also be discussing other relevant pieces of information that might interest you.
To find out more, keep reading below as we look closer.
However, before we start we must first define what a star is. A star is a gaseous body in which there is sustained hydrogen fusion in its core. The body must be sufficiently massive to create a high enough temperature and pressure to cause fusion in its core. As such, a body must be a minimum mass to be a star.
If a body does not have enough mass to create sustained hydrogen fusion, it may be classified as a brown dwarf.
What is the Smallest Star in the Universe?
So, why not just jump straight in and answer the question? What is regarded as the smallest star in the universe? Well, some of the tiniest stars in the universe are known as red dwarfs.
One star close to Earth that is regarded as a red dwarf is known scientifically as Proxima Centauri. It is only 14.5 percent of the size of the sun.
But this isn’t considered to be the smallest star in the universe.
The smallest star known in the universe is known as EBLM J0555-57Ab. This star is about the same size as Saturn. It is about 600 light-years away from us.
EBLM J0555-57Ab has a mass of about 0.09% of the mass of the Sun. It has a radius of 36,660 miles (59,000km), which is 0.08 solar radii. Scientists believe it is about the least massive a body can be to be a star.
However, this isn’t to say that there aren’t smaller stars out there, but this is the smallest recorded star we have discovered thus far.
You may be wondering why Jupiter and Saturn are not stars. Neither of these planets has fusion occurring in their cores. While EBLM J0555-57Ab is about the same size as Saturn and smaller than Jupiter, its mass is much greater. In fact, its mass is about 85 times greater than that of Jupiter.
What is the Smallest Size a Star Can Be?
As stated above, to be considered a star a gaseous body must have enough mass to sustain nuclear fusion. What mass does this occur.
Physicists have determined that a body must be about 0.075 solar masses to have sustained nuclear fusion.
Given this EBLM J0555-57Ab is only a little over the limit.
If a gaseous body fails to gain enough mass it may be considered a brown dwarf. Brown dwarfs are bodies that are intermediate in size between stars and planets (brown dwarf). At the lower end they overlap with the giant gas planets. These bodies glow in infrared radiation. Some consider them as failed stars.
What is the Biggest Star in the Universe?
Now that we know the smallest star in the universe, it would be amiss of us not to look at the largest.
The largest known star in the universe is UY Scuti, which is classified as a red supergiant.
It’s a total of 1,700 times larger than the sun’s radius. It’s hard to picture this in your mind’s eye, but it essentially means it could fit approximately 5 billion suns into its sphere. It has a mass of seven to ten times that of the Sun.
It’s important to note that UY Scuti is not large because of its mass. It is a star that is nearing the end of its life. During this process, it swells. It will eventually go supernova and a neutron star will likely be left behind.
The most massive star known is Westerhout 49-2. This behemoth is 250 times more massive than the Sun.
As a side note, the more massive a star is, the shorter it will exist as a star. This is because they ‘burn’ through their available hydrogen at a prodigious rate. For example, a star that has the same mass as eight suns will last about 100 million years. The most massive stars will burn through their hydrogen in less than a few million years (Giant Stars).
The largest stars in the Universe are blue in color. If you would like to know why our article called What Color Are The Hottest Stars may be of interest to you.
Some Interesting Facts About Stars
Now that we’ve taken a closer look at the smallest and largest stars in the universe, we can discuss some more interesting facts about these celestial objects.
Stars are something we’ve observed countless times, but it’s surprising how much we don’t know about them. Below, we take a closer look at some surprising facts.
Red Stars Have The Coolest Temperatures
This is something that many novice astronomers don’t realize at first, as it goes against common sense.
But, the stars that appear reddish in your telescope have the lowest surface temperatures. At lower temperatures, they emit a higher percentage of red light. As stars heat up, they emit a lower percentage of red light. As the surface temperature progressively gets hotter, the light eventually turns white, before reaching a bluish hue.
The hottest stars you’ll observe are those with a distinct blue color.
If you want to understand more about how color changes due to surface temperature, you should investigate black body radiation.
The Sun Is Considered A Star
Our sun is considered to be a dwarf star. The sun is the closest star to Earth, approximately 93 million miles (150 million km) away.
It has been converting hydrogen into helium for approximately 4.5 billion years and is expected to continue for around 7 billion years.
The sun is expected to run out of fuel subsequently and, as a result, will swell to consume the inner planets. Once nuclear fusion has ceased, the Sun will become an object called a white dwarf.
Stars Often Come In Pairs
Looking out into the night sky, it may appear that stars are all individual objects. This can give the impression that all stars are alone in the universe.
This simply isn’t the case because most stars come in pairs. They’re called binary stars. Binary stars orbit the same center of gravity. Astronomers estimate that up to 85% of stars occur in binary systems. Some stars occur in systems containing more than two stars.
There Are More Out There Than You’d Expect
Another interesting fact is that there are probably far more stars than you’d initially expected.
There are approximately 400 billion stars in our galaxy. With such a high number some of them may even be able to facilitate life.
All of the stars in our universe are incredibly far away from Earth. Our closest star is Proxima Centauri, which is about 4.2 light years away.
To put things into perspective, it would take humans thousands upon thousands of years to reach Proxima Centauri.
Final Thoughts
To sum up, the smallest star in the universe is EBLM J0555-57Ab, a red dwarf star. It is slightly smaller than the largest planet in our solar system and is 0.08 solar radii. However, it is denser and, as a result, has significantly more mass.
On the other end of the spectrum, the largest star in our solar system is the UY Scuti. This star is classified as a supergiant. It’s a total of 1,700 times larger than the sun’s radius. However, the most massive star is Westerhout 49-2.
Now that you know the sizes of stars, you may want to know how they produce energy.
Hi, my name is Jason Anderson, and I am a Physics Professor. Ever since I was a kid, I’ve been fascinated with space, the universe, the moon, you name it. I spent hours and hours at the planetarium close to my hometown, wondering what else could be out in the universe.
Since then, I’ve been an avid stargazer and astronomer, and love nothing more than spending my time charting stars, observing planets, and finding constellations.
This is why I decided to start Telescope Guru. I only wish to share this fun pastime with the world. With this site, I hope to answer all of your questions relating to astronomy, telescopes, and stargazing.
