Hyper giant

[CedrikG]

Hi!

I am a little bit confuse and maybe some of you can help me understand something. I always been told that the bigger a star is, the more bright blue it get. Just like a camp fire, as the star get very hot it turn blue and as the fire is close to die the flame are red.

now, some of the biggest star known are called Red giant and red hyper giant. I was wondering why these star were not bright blue ?

Thanks !

[ronin]

In a blue star you are looking at the star itself as you would look and see our sun.

In a red giant it is the outer shell that you are seeing.

The red giant has entered it's dying stages and the core has collapsed to an extent and in doing so the outer layers are thrown off and form a shell around the remains.This shell is bigger and cooler.

Eventually the core will go bang, when the present fusion process cannot be maintained, and you get a nova or supernove.

To an extent it is not the star you are seeing but the shell surrounding the star.

Our sun will form one (red giant one day).

[Davey-T]

Have a watch of this series of vid's'

Dave

[CedrikG]

ahhhhhh ... ok ok ! I really misunderstood something. I really did not think that we were considering the beginning of a nova still as a star. So like the Canis Majoris is not a MONSTER star but the beginning of a nova.

ok I completely understand. Thanks a lot man. I will watch this video right away. I might have a last question, the video might answer it but I will ask anyway.

Tell me if im right :
The smallest star  burn very very slowly and just run out of fuel, as they run out of fuel they become a very faint object with little gravity, without creating a nova. A medium sized star like our sun goes red giant, eventually becoming a nova (nebulae), eventually revealing the crushed core, a white dwarf. That white dwarf is faint and does not have an extreme gravitational force neither. It will be like that forever if it does not suck up the gaz of another star. Bigger star get crushed further by the surrounding gaz and bounce back violently, producing a supernova. In the middle of a supernova is a Neutron star, most of Neutron star are Pulsar as they suck the gaz around them and cannot contain all this material, so the material get ejected on both pole creating the beam of light we see. In the giant blue star, the biggest we know, the explosion is called hypernova, the core get soooo compressed that we end up with the most compacted object known, which gravity is so strong that not even light can escape it, a black hole. There are different size of black hole, the biggest one in the center of galaxy eat so much material that they cannot contain it, just like the neutron star the gaz get ejected but in a much stronger way, creating a Quaasar. A Quaasar and Gamma Ray Burst is pretty much the same thing.

Am I understanding it correctly ?

[CedrikG]

This video was amazing, thanks a lot !

[LukeSkywatcher]

ahhhhhh ... ok ok ! I really misunderstood something. I really did not think that we were considering the beginning of a nova still as a star. So like the Canis Majoris is not a MONSTER star but the beginning of a nova.

ok I completely understand. Thanks a lot man. I will watch this video right away. I might have a last question, the video might answer it but I will ask anyway.

Tell me if im right :

The smallest star  burn very very slowly and just run out of fuel, as they run out of fuel they become a very faint object with little gravity, without creating a nova. A medium sized star like our sun goes red giant, eventually becoming a nova (nebulae), eventually revealing the crushed core, a white dwarf. That white dwarf is faint and does not have an extreme gravitational force neither. It will be like that forever if it does not suck up the gaz of another star. Bigger star get crushed further by the surrounding gaz and bounce back violently, producing a supernova. In the middle of a supernova is a Neutron star, most of Neutron star are Pulsar as they suck the gaz around them and cannot contain all this material, so the material get ejected on both pole creating the beam of light we see. In the giant blue star, the biggest we know, the explosion is called hypernova, the core get soooo compressed that we end up with the most compacted object known, which gravity is so strong that not even light can escape it, a black hole. There are different size of black hole, the biggest one in the center of galaxy eat so much material that they cannot contain it, just like the neutron star the gaz get ejected but in a much stronger way, creating a Quaasar. A Quaasar and Gamma Ray Burst is pretty much the same thing.

Am I understanding it correctly ?

I dont really know much if anything about the life span of stars. It doesnt interest me. I thought blueish-white stars are young stars. Red giants (Betelguese) are stars coming to the end of their life. Our Sun will become a red giant in about another 5 billions years and then die............enveloping and destroying at least Mercury,Venus and Earth. 

Also i thought that the smallest stars burn off there fuel very quickly and die, while bigger ones burn off fuel much slower.

[Gazabone]

I dont really know much if anything about the life span of stars. It doesnt interest me. I thought blueish-white stars are young stars. Red giants (Betelguese) are stars coming to the end of their life. Our Sun will become a red giant in about another 5 billions years and then die............enveloping and destroying at least Mercury,Venus and Earth. 

Also i thought that the smallest stars burn off there fuel very quickly and die, while bigger ones burn off fuel much slower.

No, it is the other way around. When you compare the size of a star to our sun, the speed at which it burns it's fuel is its size compared to our sun to the forth power; a star that's twice the size of our sun will use its fuel 2x2x2x2 = 16 times faster. As it has twice as much fuel it will last 1/8 of the lifetime of our sun. If its 3x the size, that's 3x3x3x3 = 81 times quicker burning its fuel so our sun will live 27 times longer. It's staggering when you think of the size of some of the stars out there but that's why it's said that the the larger the star, the faster it lives and the younger it dies. To the op, your summary in your follow up post is how I understand it, nicely summed up, thanks.

[CedrikG]

Very interesting post everybody thanks for clarify thing. Really cool.

[LukeSkywatcher]

No, it is the other way around. When you compare the size of a star to our sun, the speed at which it burns it's fuel is its size compared to our sun to the forth power; a star that's twice the size of our sun will use its fuel 2x2x2x2 = 16 times faster. As it has twice as much fuel it will last 1/8 of the lifetime of our sun. If its 3x the size, that's 3x3x3x3 = 81 times quicker burning its fuel so our sun will live 27 times longer. It's staggering when you think of the size of some of the stars out there but that's why it's said that the the larger the star, the faster it lives and the younger it dies. To the op, your summary in your follow up post is how I understand it, nicely summed up, thanks.

Thanks for that.