if stars are formed from molecular clouds

a reply to: Belcastro

You are misunderstanding a stars ignition. On earth we need air, space, fuel, heat for something to ignite. A star needs mass and compression because it's ignition is the beginning of fusion. The fusion produces heat it does not require it.

thanks for all the answers, i learned something today

cheers

originally posted by: TheConstruKctionofLight
a reply to: hubrisinxs

The work done to compress the gasses in the star formation

What process compress's the gas?

a reply to Brotherman

liquid state there will be gas as it is on the outside and that is flammable

How is a gas flammable in the vacuum of space?

Fire as you know it is when energy is released when Oxygen combines with what ever fuel you are "burning", stars don't work that way. Fire is a reaction of a molecular bond occuring, stars "burn" because the atoms are being pressed together so hard they fuse turning two atoms into one thus releasing a bit of energy. The fusing is why we have multiple elements instead of just one. Your entire body is made of star dust.

a reply to: Belcastro

As a hydrogen/gas cloud contracts into a sphere, you have a tremendous amount of infall energy that comes from conversion of gravitic potential energy to kinetic energy in the gas (temperature).

That's all you need, if you've got enough material.

That's also why gas giants have hot cores and one reason rocky worlds like Earth have molten cores.

a reply to: Belcastro

Well there are gas giants these are basically unignited stars... if we think about the sun as it starts to end its life it will swell outwards consume closer planets to give it energy for awhile longer... this will likely ignite jupiter when it occurs billions of years from now, but much like the habitable zone close enough to a star were it can support life different star types different habitable zones btw... but same with gas giants they can enter a zone and ignite into the new star in the system as the old star goes poof into its next phaze.

Of course stars being of different types or compositions have to do with its core and gas cloud... metals being heavier they will bind and attract as the density with the most attraction, and as things spin and collece together settle in as the core... heaviest metal is likely the core although most are likely the same as the metal meteorites found as they are large chunks most common to start formation if trapped in a stable orbit many planets have rings so of course all of that particulate will start ionizing charging and attacting to each other like static cling.

some of these metals will obviously ignite on their own without much effort like magnesium is a very volitile metal have a collision of flint hit a dense patch of magnesium with a hydrogen cloud and its go time... and will of course keep burning and consuming as long as there is fuel. Stars and planets are always gaining mass from collisions of meteorites te same as when they were first forming just the chunks of attraction get bigger and well some vectors just coincide attraction aside the point.

In short




And here's the full funny version...

It's really important to understand that stars are not "on fire". The sun is NOT a ball of gas that is burning. It is a ball of gas that has a nuclear fusion engine in its center, and the heat of that nuclear fusion is radiating outward into space in the form of light, and heat when that light interacts with other matter. It is NOT combustion.

originally posted by: TheConstruKctionofLight

What process compress's the gas?

Gravity.

When a large amount of hydrogen (and other stuff) gets stuck together by gravity into a big ball of hydrogen and other stuff, then the gravity on the inside of that big ball causes the hydrogen atoms begin bumping into each other through kinetic energy.

Eventually, the HUGE amount of gravitational pressure pushing in on the core of the ball of hydrogen plus that kinetic energy plus becomes so great that the hydrogen atoms to fuse together (hence the term "fusion").

In short, stellar fusion is atoms of hydrogen fusing together to produce helium. The nucleus of the resulting helium atom that is smaller in mass than the sum of the hydrogen atoms that made it, with that leftover mass expelled by the reaction as energy.

So, that energy created from the leftover mass in the hydrogens → helium reaction is the energy given off by a star.

originally posted by: Bedlam
a reply to: Belcastro

As a hydrogen/gas cloud contracts into a sphere, you have a tremendous amount of infall energy that comes from conversion of gravitic potential energy to kinetic energy in the gas (temperature).

That's all you need, if you've got enough material.

That's also why gas giants have hot cores and one reason rocky worlds like Earth have molten cores.

Where does the energy come from in the first place though? I always thought that you couldn't actually get any energy from Gravity itself. A hydroelectric power plant for instance isn't getting its energy from gravity pulling the water downward, the energy was put into the system by the sun evaporating the water upward and then we extract it as it falls again.

To start fusion you need a large amount of energy before the fusion energy is available, and if gravity alone is producing large amounts of energy doesn't that kind of give some legitimacy to all those free energy nuts who talk about extracting energy from gravity? (to which everyone replies gravity doesn't create energy, but evidently it does during star formation?)

Serious question thanks in advance!

originally posted by: James1982
Where does the energy come from in the first place though? I always thought that you couldn't actually get any energy from Gravity itself.

You can't make a perpetual motion machine from gravity, because lifting the weight takes the same energy as dropping it.

In this case though, you've got a lot of gaseous material all spaced out that's mutually attracting the other particles. Once a gravitational collapse starts, the material all falls together to the centroid, exchanging gravitational potential energy for kinetic energy in the gas.

Consider rocks on a hill. They have gravitational potential energy with reference to the ground level below. They can fall down, releasing that potential energy first as kinetic energy in the rock, and then as heat, vibration, sound, deformation of materials and the like. Where did THAT energy come from? From the process that put them at the top of the hill to start with.

So in the case of a celestial body that is formed by gravitic collapse, the energy is in the separation of the various parts from each other. The process that deposited them there is where the energy came from.

A hydroelectric power plant for instance isn't getting its energy from gravity pulling the water downward, the energy was put into the system by the sun evaporating the water upward and then we extract it as it falls again.

Same thing. Only with a process that deposited the gas in that area scattered out. The separation is where the energy is.

And actually, in your example, you ARE extracting gravitational potential energy from the water, it's being exchanged for kinetic energy in the water. What put the gravitational potential energy there was evaporation.

What CAN'T happen is that you extract that energy, and then the water magically falls up to the top by itself. THAT'S what gravitational perpetual motion machines require.

To start fusion you need a large amount of energy before the fusion energy is available, and if gravity alone is producing large amounts of energy doesn't that kind of give some legitimacy to all those free energy nuts who talk about extracting energy from gravity? (to which everyone replies gravity doesn't create energy, but evidently it does during star formation?)

It all makes sense when you understand where the energy comes from. Gravity ISN'T producing energy. You have gravitational potential energy that's already been put there by the Big Bang, or by subsequent Little Bangs as previous generation supernovae scattered heavier elements.

Your energy extraction nuts would have the material falling together, extracting that energy, then somehow having it all scatter again. THAT'S what you can't have. Rolling the rock up the hill takes as much energy as the rock rolling back down.

In this case, the rocks come prepositioned at the tops of hills.

Great explanation Bedlam, thanks! My mistake was assuming the particles have just been floating around for eternity, wasn't thinking big/long enough

a reply to: AshOnMyTomatoes

Its important to note what started that chain reaction as per the question... pointing to the current state and what is occuring is being captain obvious to current information... someone here already has that duty, not that micro either called phage.

a reply to: Belcastro

Current thinking these days is that stars are mostly made on programs like The X Factor or The Voice and such...
The majority of these stars only last for around a year before they self absorb and there egoic cores go super nova. As with previous stars of a similar nature. Otherwise they don't generate enough "heat" and lose exposure to the attention of the mass.
It is has been proved that exposure to the mass is critical for stars to be formed, and unlike as previously thought, it has little bearing on the actual substance of a potential star.

I find these astrology subjects fascinating btw

a reply to: surfer_soul

Ego is like a blackhole nothing can escape it not even ones self... thats the gravity of such atypical thinking. Conceptual structures or theory are like saying hey you guys wanna see a dead body? Ive got sticks...

a reply to: BigBrotherDarkness

I think get the gravitas of what you are saying

a reply to: surfer_soul

Salut

originally posted by: BigBrotherDarkness
a reply to: AshOnMyTomatoes

Its important to note what started that chain reaction as per the question... pointing to the current state and what is occuring is being captain obvious to current information... someone here already has that duty, not that micro either called phage.

That fact that it isn't a combustion reaction (i.e., it's not a burning ball of hydrogen) is meaningful to the OP's question.

The OP asked "I'm wondering what caused the ignition or spark for each star to start?". However, as AshOnMyTomatoes pointed out, there was no ignition or spark needed to get the Sun going (which would be needed if it were a burning ball of gas) -- just pressure and kinetic energy to get the fusion reaction started.

a reply to: Soylent Green Is People

In that case alert black holes they are doing it wrong... and should be suns

a reply to: BigBrotherDarkness
Many very massive stars will become black holes. Fusion keeps them from collapsing, but once they run out of fuel, then there's nothing to stop the further collapse and the remnant of the star can become a black hole if it's over something like three solar masses. If the remnant is only say 1.4-2 solar masses, it can become a neutron star instead of a black hole, and if it's less than 1.39 solar masses (the Chandrasekhar limit), the electron degeneracy pressure prevents further collapse and the star remnant simply becomes a white dwarf which is how our sun will end up.

originally posted by: Arbitrageur
a reply to: BigBrotherDarkness
Many very massive stars will become black holes. Fusion keeps them from collapsing, but once they run out of fuel, then there's nothing to stop the further collapse and the remnant of the star can become a black hole if it's over something like three solar masses. If the remnant is only say 1.4-2 solar masses, it can become a neutron star instead of a black hole, and if it's less than 1.39 solar masses (the Chandrasekhar limit), the electron degeneracy pressure prevents further collapse and the star remnant simply becomes a white dwarf which is how our sun will end up.

Thank you sir well aware of that sir, but is it is just pressure and kentic energy as te other poster said, ten thats essentially a black hole which means the damned thing could become a sun... see what Im saying? Of course it ran out of fuel and thats why it novas in the first place... but its obvious that it isnt just pressure and kinetic energy as planets have the same damned thing going on as well, its a big damned ball of gas like gas giants etc that go into nuclear meltdown from thermal expansion with an atmoshere to support the chain reaction continuing like a big fing ball of lava venus isnt that far from it being over 80% volcanic activity at its surface of course the gas surrounding venus in its atmoshere isnt as palatable for a chain reaction than say Jupiter but of course it isnt out of the question if theres a chance of a hydrogen reaction...

Simple stuff here really, I dont see why people get crazy over it... infinite universe with no beginning or end, huge body of plasma and tons of particles massed and massing together slowly in the vacuum of space due to whimps champs and relative charges most of these particles like to bind and coallese with ones of the same element or affinity to bind... but of course over time all of the elements lose a particle in a half life and become another element altogether, heating and crystalizing under pressure and expansion. of course its not much different when gold panning te heaviest crap is going to settle to the bottom or in the case of planets towards its core, and the lightest ones are going to eventually fill an atmosphere as all the elements making the planet planetoid what have you outgas from the conglomerates that formed the stupid thing.

So take the heaviest element and bam that junk is eventually going to be core material and the lightest and that will eventually be the atmosphere element... of course it depends on the huge cosmic furnice inwhichh they coagulate and bind together that determines their make up, of course collisions and impacts over time also add to this conglomerate mass and change up the elemental make up... suns come from gas giants and their color is dependent on whatever elemental liquid, solid gas was most present at the time it ignited.

So staring at a damned sun already formed saying its in chain reaction is 5th grade science material saying its pressure and kinetic energy with no freaking fuel means all of it is a damned sun...

please no body reply to me in this thread again it gives me headaches for you... its honestly not as complex as its made out to be, hell I theorized nebulas forming stars and gas giants a sun too cool too ignite and the habitable zone based around mountain climbings habitable zone in 1992... the important thing to remember looking at this crap is its so far away its back in time when we see it and moving in super slow motion for the most part... sans stellar winds that can zip along near light speed like a river of particles cutting a steady slough through space as the whole galaxy spins, all the solar systems spin zooming towards the center of a super massive black hole, making a galaxy nothing more than a damned accretion disk flapping out by its lonesome in intersteallar space.