The Stars-Blog Entry

1.What is a star?

Stars are huge balls with gas and dust. Stars are made of a huge cloud called Stellar Nebula. This huge cloud starts getting smaller because of the gravity and while it gets smaller, it gets hotter too and nuclear reaction stars in the middle. After all this, a star is born. If we look up in the sky, they look really small, but in fact, they are much bigger, hotter and brighter. Stars have different names, color, size, type, temperature, magnitude(luminosity) and spectral class. Stars can be blue, yellow, orange, red and white. Blue stars are consider as hot stars and red stars are consider as cold stars.

2. Types of Stars

Stars have different types and those types are: super giant, giant, main sequence and white dwarfs.
Super giant stars which are one type of stars, are known as the largest stars and some of them are bigger than our solar system. When these type of stars die, they turn into supernovas and become Black Holes. Some of these stars are: Betelgeuse, Rigel and Deneb.

Giant stars are one other type of stars. They are huge stars and they have different color, size temperature and magnitude. They have spectral class too which represents the temperature of the star and the letter changes according to the star temperature. Some of these stars are: Polaris(North Star) and Aldebaran. 

Main sequence stars are type of young stars with different color, size, temperature and magnitude. These stars lay on a diagonal from hot and bright stars to cold and dim stars. One important star that is included in this type of stars is Sun.White dwarf are type of stars in which the stars of this type are consider as small, hot stars. The stars of these type, as all the other stars have different color, size, temperature and magnitude. They have almost the same size as Earth but they are heavier. When these stars lose their heat and become cold, they will become Black Dwarfs and some of these stars are: Sirius, 40 Eridani B and Procyon B.

3. H-R Diagram

H-R Diagram is also known as "The Hertzsprung- Russell Diagram"and is a diagram used by astronomers to classify stars according to their luminosity, spectral class, color, temperature and evolutionary stage. This diagram shows types of stars which are: super giant, giant, main sequence and white dwarfs.

4. Nuclear Fusion

Nuclear Fusion is a reaction inside the star that changes two Hydrogen (H) gas molecule into Helium (He) molecule. Nuclear Reaction helps a star to born because the huge cloud or Stellar Nebula gets smaller and while it gets smaller, it gets hotter too and inside of it Nuclear Reaction happens. Nuclear Reaction is a Reaction that creates the main source which is Energy.

5.The Life Cycle of a Star
Sun-like stars, huge stars and giant stars are three different groups of stars that have different life cycle but all of them are created from a huge cloud with gas and dust called Stellar Nebula.

Sun-like stars first starts with Stellar Nebula and then it becomes Red Giant. After it become red giant, become a cloud with gas and dust called Planetary Nebula. After this, it becomes White Dwarf and than turns into a cold, dark object called Black Dwarf.
Huge Stars starts with Stellar Nebula too and it becomes bigger to a Red Super Giant, but than it explodes to a Supernova and starts to collapse into a Neutron Star.
Giant Stars starts from Stellar Nebula, it gets bigger into a Red Super Giant, explodes into a Supernova but at the end, become an invisible object called Black Hole.