Stars are some of the most important celestial bodies in our universe. We've already talked about some of the most fascinating – and deadliest – planets orbiting the stars, but these luminous luminaries are intriguing by themselves.
We often think of stars as huge, hot, round hydrogen masses and helium, although this is not always the case. Astronomers have discovered many stars that destroy our well-established beliefs. These discoveries are strange and ultimately fascinating.
10 The egg-shaped star
What's cooler than a round star? Obviously, one that is shaped like an egg.
Enter Vega (aka Alpha Lyrae or Alpha Lyr), an egg-shaped star that is 25 light-years from us. It's one of the most popular stars ever, and astronomers seem to study it more than our own sun.
Vega has a strange shape due to its super-fast rotation speed, which is 93 percent of its critical speed (aka "critical rotation" is the maximum speed at which the star would break apart). Vega is so fast that it completes one turn around its axis in just 12.5 hours. Our sun is ready in 27 days.
This makes Vega 23 percent wider at the equator than at the poles. The abnormal shape has carried so much energy away from the equator that it is 2.200 degrees Celsius cooler than the poles. 
9 Two Massive Stars Merging into One
Over a decade ago, astronomers discovered a massive star in the constellation Camelopardalis ("Giraffe"), 13,000 light-years from Earth. They called the system MY Camelopardalis.
Originally, amateurs thought they would see a single massive star. However, astronomers soon noticed that they were looking at two massive stars orbiting each other closely. In fact, the partners circle each other in just 1.2 days.
The larger star has 38 times the mass of the Sun, while the smaller one has 32 times the mass of our Sun. The astronomers later realized that one day the partners would clash and create a giant star with 60 times the mass of the Sun. 
Actually the atmosphere of the stars are already interacting. This is continued until the star nuclei finally merge into one. Astronomers do not know exactly what will happen at this time. They speculate, however, that the merger will trigger a big explosion that releases massive energy.
8 The star with the spiral arms
When we think of spiral arms, we imagine galaxies like the Milky Way galaxy. The star SAO 206462 is here to prove the opposite, because it has two spiral arms. SAO 206462 is located in the constellation Lupus ("Wolf"), about 460 light-years from Earth. The star is surrounded by a very broad circumstellar disk of dust and gas. 
This wide disc is almost twice the width of Pluto's orbit. Astronomers know that spiral arms can develop around a star as new planets emerge in its disk. In fact, they believe that the two spiral arms were formed by two new planets that developed within the disk.
7 The star with the clouds of water
We know that stars are incredibly hot. For example, our sun is on average 5,500 degrees Celsius in the photosphere. How about a star with only 100 degrees Celsius? This is the boiling point of water that is too cold for a star. However, this is the temperature of CFBDSIR 1458 + 10B (see figure above right).
It is a 75-year-old Brown Dwarf in the CFBDSIR 1458 + 10 binary system. A binary system has two stars orbiting each other.
The mass of a brown dwarf lies between that of a giant planet and a small star. It's too big to be called a planet, but too weak to be considered a true star. Brown dwarfs are considered fancy stars because they do not have enough mass for gravity to trigger a nuclear fusion. This is how stars generate light and heat.
CFBDSIR 1458 + 10B is too cold even for a brown dwarf. The temperatures of most known brown dwarfs are often between 177 and 327 degrees Celsius, which is still considerably warmer than the 100 degrees Celsius of CFBDSIR 1458 + 10B.
Astronomers believe that conditions continue to exist CFBDSIR 1458 + 10B are more like those of a large planet than those of a normal brown dwarf. They even believe that this cold brown dwarf could have clouds that contain water. 
6 The star that became a diamond planet
It does not often happen that we become a star of a star, let alone a diamond-covered planet. But this unnamed star did just that.
Astronomers discovered the star-twisted planet when they received some pulse signals in our Milky Way galaxy. Pulse signals are radio waves and radiation emitted by fast-spinning neutron stars, the collapsed cores of dead giant stars.
Astronomers found that something was wrong when they discovered that the spin of the pulsar seemed to be affected by gravity. This type of spin could only occur if an exoplanet orbits the pulsar.
In fact, astronomers discovered an exoplanet that quickly orbits the pulsar at close range. The exoplanet also had a very large mass (like that of Jupiter), although it was only five times larger than Earth. That made no sense at first. An exoplanet orbiting so close to a star with high gravity should not have such a large mass packed so tightly.
Astronomers soon discovered that the exoplanet was once a star that was part of a binary system. The Pulsar had been the second star, and the two had been circling each other. However, the stars eventually burned their fuel and came so close that the larger one tore the matter from the smaller star. 
The result was a cold planet circling a pulsar. The destruction, however, holds beauty. Astronomers believe that the fuseless planet is made of crystalline carbon, the same material that makes up diamonds.
5 The star within a star
A Thorne-Cytkov object (TZO) refers to a star that forms diamonds in another star. The object was named after the physicist Kip Thorne and the astronomer Anna Zytkow. Together in 1975 they proposed the existence of such a star. Thorne and Zytkow said that TZOs are formed when a neutron star is consumed by a red supergiant star.
As already mentioned, a neutron star is the collapsed nucleus of a dead giant star. A red supergiant is an old star that almost runs out of hydrogen – an important element in generating light and heat. Red supergiants are the largest stars in the universe and can reach 2000 times the size of our Sun.
In 2014, astronomers believed that they had found a TZO, which they called HV 2112. The star was located in a dwarf galaxy 199,000 light-years from Earth. The HV 2112 resembles a very bright red supergiant. However, it is considered TZO because it contains large amounts of some elements that are not released by typical red supergiants. 
4 The Roundest Star
We often think that planets and stars are round, even though they are not. They are actually wider along their equators due to the centrifugal force that occurs when rotating. About 5,000 light-years from Earth is Kepler 11145123, a star that is the roundest natural object known to date.
Typically, the faster the rotation is, the broader the star or planet at the equator. The earth is not perfect around. The sun and the star Kepler 11145123 are not. Kepler 11145123 approaches, however.
Earth is 21 kilometers wider at its equator than at its poles. Using the same relative measurement, the Sun is about 10 kilometers (6 miles) wider and Kepler 11145123 is only 6 kilometers (4 miles) wider. This is particularly impressive since Kepler 11145123 is twice as large as the sun.
Astronomers agree that their diameter estimate for Kepler 11145123 could differ by a few kilometers. However, this is a small error rate. On average, Kepler 11145123 has a diameter of 3.2 million kilometers. 
3 A star smaller than Jupiter
We often regard stars as large celestial star bodies, though this is not always the case. They could be much smaller, say the size of Saturn. Saturn seems huge compared to Earth: About 764 Earths would fit in Saturn.
That is still much smaller than the size of our sun. About 1.3 million earths would fit in the sun. Saturn is also smaller than Jupiter, the largest planet in our solar system. Nevertheless, astronomers have discovered a star the size of Saturn. This star is called EBLM J0555-57Ab and is 600 light-years away from us.
EBLM J0555-57Ab would not have enough internal pressure to allow nuclear fusion if it were smaller. As already mentioned, stars generate heat and light through nuclear fusion. This size is just right to meet the minimum mass requirements for nuclear fusion in a star. Anything smaller, and it would have been a brown dwarf – one of those failed stars whose mass is insufficient to induce nuclear fusion by gravity. 
2 The Epsilon Lyrae multi-star system is 160 light-years from Earth. This fascinating system holds a little surprise. It looks like a binary system in which two stars orbit each other. On closer inspection, each of these stars is itself a binary number. In other words, each star is made up of two stars orbiting each other. Each pair also circles the other pair. As a result, the system contains two binary files within a binary file (also known as "The Double Double").
From Earth, each star pair seems so close to each other that we could confuse both stars in any amount for a single star. This happens even though these individual stars are actually so far apart that it takes them about 1,000 years to complete a single orbit around the other in their star pair.
The binaries themselves are also far apart. The distance between the two sets is 10,000 times the distance between Earth and Sun. The binaries take about 500,000 years to complete a single turn around each other.
Interestingly, astronomers have discovered a fifth star orbiting one of the star pairs. These space scientists also believe that other undiscovered stars orbit in Epsilon Lyrae. Overall, astronomers think that the system includes 10 stars. 
1 The Star with the Tail
When we think of tails in outer space, we usually imagine comets. Mira ("Wonderful") is here to prove the opposite. It is a double star in the Cetus constellation, 350 light years from Earth. One star is a red giant named Mira A and the other is a white dwarf named Mira B. A red giant is a dying star, while a white dwarf is a dead star.
Astronomers discovered the stars as they examined the universe in ultraviolet light. They found out that a comet had left a tail that was 13 light-years long. That's 20,000 times the average distance between Pluto and the Sun. However, they soon discovered that the tail actually came from the red giant Mira A.
The tail drops various elements, including carbon and oxygen, which astronomers believe could create new solar systems. Mira has been bringing these items to market for over 30,000 years.