Since the emergence of the Hubble Space telescope, we have discovered many distant galaxies, thousands of exoplanets and even peeked in our past, but one thing that astronomers are still not sure about is how many stars actually are there in the Milky Way, let alone in the entire Universe. Like any living things, stars die and take birth in a rather spectacular event.
As always, we have compiled a list of facts about stars that you might find interesting and useful. So do you think you know everything about the stars? Let’s check out.
15. Brightest Star in the Night Sky
From Earth’s point of view, Sirius A is the second brightest star in the sky only after the Sun. Located in the constellation Canis Major, the star is believed to be slowly approaching our Solar system at a speed of 5.5 km/s and in 60,000 years, Sirius will make its closest approach to the Earth at a distance of about 7.8 light years. Sirius A is about twice as massive than the Sun and 25 times more luminous.
14. Galaxy’s Most Mysterious Star – The Tabby’s Star
Over the years we came across hundreds of weird stars in the distant reaches of the sky. But none of them are more mysterious than the KIC 8462852 popularly known as the Tabby’s star. The star is known for its highly unusual fluctuation of light which is observed from the Earth.
Since the beginning of the 21st century, numerous ups and downs in its brightness has been observed most notably in 2011 and 2013. During that time star’s brightness dropped by almost 22%. Then again recently in 2017, multiple dipping in stellar luminosity was observed, but this time a slight increase in luminosity was also detected.
13. Largest Star in the Milky way
Our Sun is huge, but compared to other stars in our galaxy, it’s actually quite small and insignificant. The biggest star discovered so far is UY Scuti. It was first discovered in the 19th century by a team of German astronomers at the Bonn Observatory, Germany. Located in the constellation of Scutum, it’s currently the largest star known to us. According to some estimations, UY Scuti has a radius of 1,708 solar radius and is 5 billion times bigger than the Sun.
12. Closest Star to Our Solar System
At a distance of 4.25 light years from our Earth, Proxima Centuari is the by far closest star to our Solar system. The next closest star is the Bernard star located at a distance of 5.9 light years. Let’s say you want to make a one way trip to the Proxima right now on-board the fastest spacecraft ever launched from the Earth (possibly New Horizons), it would still take you around 80,000 years to reach there. Well, unless you are travelling at the speed of light and in that case it would take only 4 years. Wouldn’t it be cool.
11. Most Massive Star
Located in the Tarantula Nebula, the star R136a1 is the most massive star in the observable universe. It has around 300 times the total mass of the Sun.
10. Formation and Evolution of Stars
Stars take birth from dense molecular clouds, which are mostly comprised of molecular hydrogen and have significant amounts of helium with small amounts of heavier elements. After birth most of the stars spend their majority of life as a main sequence star, creating energy by burning hydrogen into helium.
However, stars with different masses acquire different properties at various stages of their development. The fate of each star is based on their mass, as do their luminosities and the impact they have on their environment.
9. Largest Globular/ Star Cluster
A globular cluster is a massive collection of stars in a relatively small region of the space. These star clusters are so tightly bound by gravity that they look almost sphere from any distant location. The Omega Centauri globular cluster is perhaps the biggest and the brightest in the Milky Way with approximately 10 million stars, scattered over 150 light years.
8. Stellar Interior
The interior of any stable star (main sequence) is in a hydrostatic equilibrium state, i.e, forces within the stars counterbalance each other almost instantly. You may not know that star’s own gravity is constantly pulling it inward. If it is not countered, the star would collapse for million of years to become its smallest possible size.
But the fusion occurring at the very core of the star pushes this gravitational force and prevent further collapse of a star. The enormous amount of energy produced by the core helps stars become more luminous, as they expand outward and become red giants. And when they run out of light pressure, they collapse down into white dwarfs.
7. How Many Stars? Any Guess
Even with the help of modern technology, scientists are only able to roughly estimate the total number of stars present in our galaxy. Astronomers believe that there are 100 billion to 250 billion stars in the Milky way alone. This estimation might be close or way off, we don’t know for sure.
Then we have around 200 billion estimated galaxies in the universe, some are smaller than the Milky Way and some are bigger. The Biggest galaxy detected yet is about double the size of the our own. If we multiply both the numbers we get 5 x 1022 or about 50,000,000,000,000,000,000,000 stars.
6. Most Massive Stars have Short Life
Less massive stars are expected to live much longer than more massive stars. The exact opposite can be said for small red dwarfs, who are burning their hydrogen in extremely slow rate. Many giants can have as much as about 150 times the mass of the Sun, means they generates a fierce amount of energy compared to the Sun.
For example, a massive star known as Eta Carinae has about 150 times the mass of the Sun and generates million times more energy. Scientists believe that at this rate it would take Eta Carinae less than 3 million years to turn into a supernova while Sun would live for another 6 billion years.
5. The Biggest Star
The Milky Way is the home for many gigantic stars. And one such star is NML Cygni. Its total volume is about 20 billion times that of our Sun but that’s nothing compared to the true monster VY Canis Majoris. For the sake of simplicity, if VY Canis Majoris is somehow placed at the center of our solar system, then its outer atmosphere would most probably engulf the orbit of Saturn.
4. Septenary Star System
Nearly 50% of stars we observe in the visible universe are actually multiple stars i.e. they come in a pair of two or more stars. You are probably aware of binary star system where two stars closely revolve around each other. One most popular example of such star system is Sirius.
On the other hand, a star system with seven stars is classified as the septenary star system. So far there are two of such star systems are discovered; Nu Scorpii, located in the constellation Scorpius and AR Cassiopeiae in the constellation of Cassiopeia. Multiple star system with a greater multiplicity are yet to be found.
3. Red Dwarfs are the Most Common
The red dwarfs are by far the most common star in the Milky Way. They have about 7-50% of the total mass of the Sun and are also very dim. On an average, red dwarfs are expected to live for several trillions of years as they burn their fuel far more slowly than giant stars and even the sun. The nearest red dwarf to our Earth is Proxima Centauri.
2. Stellar Classification
Stellar classification is a process where stars are classified based on their visual or spectral characteristics. As of now most of the stars are classified according to the Morgan-Keenan system. The system uses English alphabets O, B, A, F, G, K, and M, to differentiate the stars. Other stellar classification systems are Harvard spectral classification, Yerkes spectral classification and the Johnson system.
1. The Sun is the Closest Star
The Sun is like a powerhouse that drives almost everything on the Earth. Simply put, life on Earth would be impossible without the presence of the Sun. While it’s a basic astronomy that its the closest star to our planet, it is quite fascinating that our own Sun represents the most common type of stars out there.
Classified as a G-type main sequence star, the Sun is slowly burning its hydrogen core and will continue to do so for the next 6 or 7 billion years, after that it will eventually become a red giant, swelling up many times its current size. As it expands, the Sun will consume orbits of Mercury, Venus and will make Earth totally inhabitable.