It depends on the initial mass of the star - i.e., how much actual material it contains. The more massive a star is, the shorter its 'life'. Most stars average out at roughly the mass of the Sun (certainly within a fairly narrow range either side of it at least) and the lifetime for such stars is therefore about the same as the Sun's - about 10 billion years. Really massive stars like eta Carinae will run through their nuclear reactions at a much faster rate and so will only last for a few million years. Eta Carinae could go supernova any day now!
they are called super novas
Most do not. Stars about 10 times more massive than the sun or larger will explode. Smaller stars shed their outer layers gradually.
When smaller stars explode (like our Sun), they leave a nebula cloud by releasing their gas and they become a small but dense white dwarf star.When big stars explode (like Betelgeuse), they have a massive explosion called a supernova and the core of the star turns into a black hole or a pulsar.
They explode with nuclear explosions.
A Galaxy could not explode. An individual star can, and does, but a Galaxy consists of billions of stars quite widely separated.
they run out of helium and eventually explode and ruin the entire solar system
Novas
No. Only the most massive stars explode.
stars explode
Depends on which 5 stars
Some stars do. They can be nova or supernova stars, depending on the scale of the explosion.
Some stars explode in a supernova.
Blue stars are the hottest, because they are newborn stars. Yellow stars are medium age stars, like our sun, and are right in the middle. Red stars are the oldest, and will explode very soon, so those are the coolest (but still pretty hot; hotter than your oven!).
they are called super novas
Most do not. Stars about 10 times more massive than the sun or larger will explode. Smaller stars shed their outer layers gradually.
well it depends on the star. not all stars explode. small to medium sized stars just go into a planetary nebula after they swell up to a red giant then the bigger stars do explode, they have a super nova after the swell up into a super giant. but dont worry i star will not explode... its a really small star. --- nichole brooks :)
Massive stars are most likely to explode faster than smaller stars.