The Astronomy Thread

Iannis_sl said:

I want to say that doesn't sound right, but I don't know enough about stars to correct you.

Behemoth star to begin with that is now at the end of its life cycle? So we can expect Canis Majoris to go supernova sometime within the next million years or so?

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Szlia_sl said:

Are we talking in cosmological terms or in everyday life terms? How sudden and how short a time?

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fucker_sl said:

pretty much yes. VY Canis Majoris is the largest known start by its volume, thousands of times larger, but its mass is calculated to be only between 15 and 35 times the Sun. Except for its core, it's made of ionized gas, so it has a very low density



yes, giant red stars are the end stage of the life of star not different from our Sun.

now, i suppose you know how stars are born......nebules and stellar dust gather together with gravity. Once a stellar object reachs a certain mass the gravitation force and pressure it will start a thermonuclear reaction inside the core.

the process involve Hydrogen being converted into Helium though nuclear fusion (hydrogen is the first, most abundant element, and require the least energy to start the process)

when hydrogen is consumed, the star starts to convert helium into Carbon. This, change the Star's size and appearence, turning it gradually from a hot yellow main sequence star to a cooler red star

now, stars like the sun, once their helium is consumed will "slow down", lose their outer layer of gas and become a white dwarf

Stars with at least 10 times the mass of the sun instead will start to fuse Helium into Carbon. More massive stars will continue this process, converting Carbon into Oxygen, then Neon, then Iron depending on how massive the star is. This process will repeat itself, changing the characteristic of the star, until it will reach the stage when Iron is created

Untill then infact, the structure of the star is kept in equilibrium between the force of gravity, attempting to "queeze" the star, and the pressure of the nuclear fusion reaction of its core, that tries to push everything appart

What happends when Iron starts to be made? everything collapse. Why ? because the Neon>Iron fusion reaction has a different characteristic.....it ABSORB energy. So, from a situation where gravity is counterbalanced by the star's internal nuclear push we come to a situation where this counterbalance disappear.

the result is a sudden core collapse. All the inner shells of the core just break down on themself. The result is a sudden compression of energy of massive scale. Energy that bounce back out, creating the stellar event we call Supernova. The Supernova explosion will cause, in the spam of very short time, the nuclear fusion of even heavier elements. All these elements will be scatered across the galaxy when the outer laiyers of the star are blown away by the explosion. Elements that will form the next generation of stars and planets. That's why elements heavier than Helium exist in the universe. Stars forge them and spread them around. As Neil Degrasse Tyson say: we are litterally stardust

depending on how massive the star was, the core will turn itself into a Neutron Star, or even a Black Hole

So, yes, Canis Majoris will explode into a Supernova. Infact, there is major discussions about the magnitude of energy that Canis Majoris will have when it will explode. That's why it won't even explode into a Supernova, it will explode into a Hypernova

of course this is a very simplied explanation. The process and events in it are way way way more complex

The Hypernova of VY Canis Majoris

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