Types of Stars
When you look at the night sky you can see many beautiful stars. If you are out in the country or camping in the mountains or the desert away from the city lights, you may see thousands of them. You may even be able to see part of the Milky Way. In a town or city, you can't see nearly as many stars because the city lights create a glow in the sky masking many of them.
There are several different kinds of stars in the sky. Some are very big. A couple of stars have been found that are 100 to 200 times larger than the sun. Some very old stars are smaller than the Earth. Scientists study stars and place them in groups based on how they are alike and how they are different.
There are seven types of stars; Main sequence stars, Red giant stars, White dwarfs, Neutron stars, black holes, brown dwarfs, and variable stars.
Stars are huge balls of gas in outer space. Made from hydrogen, helium and other elements, stars produce light, heat and other forms of energy. The twinkling stars that you observe in the night sky are actually very far away from the earth. The Sun is also a star, but is much closer to Earth and hence looks like a huge glowing ball.
The Sun has planets and other objects moving around it. Our Sun, Earth, other planets and rocky objects together are called the Solar System. Many stars have planets moving around them too.
1. Main Sequence Star
A star is said to be born once nuclear fusion commences in its core. At this point it is, regardless of mass, considered a main sequence star. This is where the majority of a star's life is lived. Our Sun has been on the main sequence for about 5 billion years, and will persist for another 5 billion years or so before it transitions to become a Red Giant Star.
A star is said to be born once nuclear fusion commences in its core. At this point it is, regardless of mass, considered a main sequence star. This is where the majority of a star's life is lived. Our Sun has been on the main sequence for about 5 billion years, and will persist for another 5 billion years or so before it transitions to become a Red Giant Star.
2. Red Giant Star
Once a star has used up all of its hydrogen fuel in its core it transitions off the main sequence and becomes a red giant. Depending on the mass of the star it can oscillate between various states before ultimately becoming either a white dwarf, neutron star or black hole. One of our nearest neighbors (galactically speaking), Betelgeuse is currently in its red giant phase and is expected to go supernova at any time
Once a star has used up all of its hydrogen fuel in its core it transitions off the main sequence and becomes a red giant. Depending on the mass of the star it can oscillate between various states before ultimately becoming either a white dwarf, neutron star or black hole. One of our nearest neighbors (galactically speaking), Betelgeuse is currently in its red giant phase and is expected to go supernova at any time
3. White Dwarf Star
When low-mass stars, like our Sun, reach the end of their lives they enter the red giant phase. But the outward radiation pressure overwhelms the gravitational pressure and the star expands farther and farther out into space. Eventually, the outer envelope of the star begins to merge with interstellar space and all that is left behind is the remnant of the star's core. This core is a smoldering ball of carbon and other various elements that glows as it cools. While often referred to as a star, a white dwarf is not technically a star as it does not undergo nuclear fusion. Rather it is a stellar remnant, like a black hole or neutron star. Eventually it is this type of object that will be the sole remains of our Sun billions of years from now.
When low-mass stars, like our Sun, reach the end of their lives they enter the red giant phase. But the outward radiation pressure overwhelms the gravitational pressure and the star expands farther and farther out into space. Eventually, the outer envelope of the star begins to merge with interstellar space and all that is left behind is the remnant of the star's core. This core is a smoldering ball of carbon and other various elements that glows as it cools. While often referred to as a star, a white dwarf is not technically a star as it does not undergo nuclear fusion. Rather it is a stellar remnant, like a black hole or neutron star. Eventually it is this type of object that will be the sole remains of our Sun billions of years from now.
4. Neutron Star
A neutron star, like a white dwarf or black hole, is actually not a star but a stellar remnant. When a massive star reaches the end of its life it undergoes a supernova explosion, leaving behind its incredibly dense core. A soup-can full of neutron star material would have about the same mass as our Moon. There only objects known to exist in the Universe that have greater density are black holes
A neutron star, like a white dwarf or black hole, is actually not a star but a stellar remnant. When a massive star reaches the end of its life it undergoes a supernova explosion, leaving behind its incredibly dense core. A soup-can full of neutron star material would have about the same mass as our Moon. There only objects known to exist in the Universe that have greater density are black holes
5. Black Hole
Black holes are the result of very massive stars collapsing in on themselves due to the massive gravity they create. When the star reaches the end of its main sequence life cycle, the ensuing supernova drives the outer part of the star outward, leaving only the core behind. The core will have become so dense that not even light can escape its grasp. These objects are so exotic that the laws of physics break down.
Black holes are the result of very massive stars collapsing in on themselves due to the massive gravity they create. When the star reaches the end of its main sequence life cycle, the ensuing supernova drives the outer part of the star outward, leaving only the core behind. The core will have become so dense that not even light can escape its grasp. These objects are so exotic that the laws of physics break down.
6. Brown Dwarfs
Brown Dwarfs are not actually stars, but rather "failed" stars. They form in the same manner as normal stars, however they never quite accumulate enough mass to ignite nuclear fusion in their cores. Therefore they are noticeably smaller than main sequence stars. In fact those that have been detected are more similar to the planet Jupiter in size, though much more massive (and hence much denser).
Brown Dwarfs are not actually stars, but rather "failed" stars. They form in the same manner as normal stars, however they never quite accumulate enough mass to ignite nuclear fusion in their cores. Therefore they are noticeably smaller than main sequence stars. In fact those that have been detected are more similar to the planet Jupiter in size, though much more massive (and hence much denser).
7. Variable Stars
Most stars we see in the night sky maintain a constant brightness (the twinkling we sometimes see is actually an atmospheric effect and not a variation of the star), but some stars actually do vary. While some stars owe their variation to their rotation (like rotating neutron stars, called pulsars) most variable stars change brightness because of their continual expansion and contraction. The period of pulsation observed is directly proportional to its intrinsic brightness. For this reason, variable stars are used to measure distances since their period and apparent brightness (how bright they appear to us on Earth) can be sued to calculate how far away they are from us
Most stars we see in the night sky maintain a constant brightness (the twinkling we sometimes see is actually an atmospheric effect and not a variation of the star), but some stars actually do vary. While some stars owe their variation to their rotation (like rotating neutron stars, called pulsars) most variable stars change brightness because of their continual expansion and contraction. The period of pulsation observed is directly proportional to its intrinsic brightness. For this reason, variable stars are used to measure distances since their period and apparent brightness (how bright they appear to us on Earth) can be sued to calculate how far away they are from us
1. How many stars are there?
2. What is our sun a part of?
3. Stars are huge balls of...?
4. What are Brown Dwarfs called?
5. When a star reaches its final stage what
undergoes?
