Objects in the universe
- Thread starter epicstruggle
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Wow,Antares is just unbelieveably large!
OpenGL guy
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If I remember correctly, Antares is so large that if it were positioned where the Sun is, it would engulf the orbit of Mars! That means it's radius is about 140 million miles!
How certain are scientists that there isnt anything larger?OpenGL guy said:
if stars this large are possible, does that mean that if they have planetary objects, they would be similarly huge? And if so, why dont we have an easier time of detecting them?
epic
epic
OpenGL guy
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Where did you get the idea that scientists think Antares is the largest star?! I've never seen such a proclamation made anywhere. It's certainly a very large star, but there are a whole lot of stars in the universe whose size we can't measure.epicstruggle said:
OpenGL guy
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Not necessarily. Also, a star would have to be near enough for us to detect any planets. Antares is quite distant (1000 light years?), so I think our chances of observing any planets there are slim.epicstruggle said:
OpenGL guy
Veteran
True enough. Antares probably started as a very large star, but is now bloated to a red supergiant because it is burning helium (hydrogen has already been consumed). When it bloated, it probably vaporized any planets that were orbiting.Neeyik said:
sorry im not too knowledeable in this area, but why does it matter if it was a binary star?Neeyik said:
OpenGL guy said:
Antares' dimensions are as much inferred as measured. There are good reasons to believe that there's an upper limit to the mass of a "normal" star which exist for meaningful periods of time. This in turn implies a limit to the size a star can attain in the supergiant phase.
Glad you liked it.DiGuru said:
I was quite amazed at the scale difference of these objects. Im still having a hard time grasping some of these things are. here is another example of scale, but in a different direction:
http://www.phrenopolis.com/perspective/atom/index.html
that web page is 11 miles wide!
OpenGL guy
Veteran
Of course there are limits: If the energy from fusion isn't enough to prevent gravitational collapse, then you get a black hole instead of a star. However, given that there are billions of galaxies, chances are there's a star that's closer to that limit than Antares.nutball said:
BTW, I think I once read that if the mass of the entire universe were packed into a black hole, the event horizon would be about to Mars' orbit as well.
Good question. The simple answer is that we don't know. The slightly more complex answer would be, that we think that the larger the star, the less chance there is on smaller planets. And the more complex answer would be, that we haven't got the means or data to calculate that in either case.epicstruggle said:
But don't expect life around there, as they will burn fiercely and fast.
Very nice!epicstruggle said:Glad you liked it.
here is another example of scale, but in a different direction:
http://www.phrenopolis.com/perspective/atom/index.html
that web page is 11 miles wide!
No that's not what I meant, and actually it's back-to-front.OpenGL guy said:
As you increase the mass of a "normal" star (ie. a star composed of non-degenerate matter) you increase the energy output of the fusion reactor in the core. This energy produced is (broadly speaking) released from the core in the form of electromagnetic radiation, radiation which exerts a "pressure" on neutral or partialy ionized gases (eg. the stellar envelope). Eventually as you increase the stellar mass you reach the point at which the radiation pressure exterted by the core on the envelope of the star exceeds its self-gravity, and blows the envelope away... basically the star is so massive and hot it boils itself into space. From this we can infer that "normal" stars cannot do the things they do above a mass of ~150-200 Solar masses.
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