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Three Largest Stars Identified
mOoZik writes "BBC News is reporting that astronomers have identified the three biggest stars known to science, having diameters of more than 1.5 billion km. If they were located in the same place as our own Sun - at the centre of the Solar System - the stars would stretch out further than the orbit of Jupiter!"
You know, large dosen't mean heavy. A Peacock feather is alot larger than my wedding ring. My wedding ring is (slightly) heavier though.
There are lies, damned lies, and statistics.
And the Green and Yellow stars have the best chance of finding inhabitable planets. Unless of course you are the Silicoids, in which case you can colonize anywhere.
no. The mass of the stars is big, but they are very far away.
/me waits for someone to point out an error in my arithmatic
Consider:
density of sun = ~1400 kg/m^3
let us assume these stars have the same density (they don't, it will be lower, but that is ok for our purposes here)
diameter 1.5 billion km = 1.5E12 m
volume (assume a perfect sphere) = 4/3 pi r^3 ~ 1.8E36 cubic metres
giving a mass of 2.5E39Kg (about 1 billion times that of the sun)
the gravitational field strength on an object obeys an inverse square relationship
F=GM/r^2
The nearest of these stars is 5200 light years away, or 5E19 metres
G is the universal gravitational constant, about 7E-11
so
F=7E-11 * 2.5E39 / (5E19*5E19)
F~ 1E-10 N/kg
for comparison, the gravitational field strength on earth is about 10 N/kg, ie 100 billion times larger.
You can think of the fusion reaction in a sun as it's 'defense' against collapse. The force driving the future collapse, gravity, is what's sustaining the fusion reaction, which creates internal photonic pressure, which in turn pushes the mass of the star outward, counteracting the force of gravity.
The reason these stars are so large is in fact directly related to the photonic pressure produced by this reaction. If the gases are very hot it prevents the gas from codensing, i.e., you need a lot of it (a big star) to combat gravity. Once these go supernovae and leave clouds of elements that burn at a lower temperature, smaller stars will be able to form.
When things get complex, multiply by the complex conjugate.
This may set a record for most mispelled words in one post! Would you like a job as an editor?
Could you please explain why destroying the relay station caused a black hole which swallowed and destroyed the hirogen ships, whereas the romulan warbirds (which also use a quantum singularity for power) which routinely get destroyed by federation ships result in only a pyrotechnical display? The mind boggles...
Red supergiants may be large, but their density have been described by e.g. Larry Niven as "red-hot vacuum." At least their outer layers are very tenuous at best. Given that the masses are typically only a few orders of magnitude more than the Sun, at most, but that their volumes are enormously much bigger, there can't be that
This means (surface) gravity is low and they can get by with less hydrostatic pressure to maintain their bulk.
The *core* is typically very dense, much denser than the Sun. Higher pressures are needed to support fusion of higher-order elements. Makes the surface layers even less dense, since a lot of the mass is still in the core.