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Three Largest Stars Identified 354
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!"
The three widest stars? (Score:4, Funny)
Thanks folks, I'll be here all week. Try the veal.
- Greg
Re:The three widest stars? (Score:2, Funny)
just wondering (Score:3, Interesting)
Re:just wondering (Score:3, Informative)
Re:just wondering (Score:2, Insightful)
Re:just wondering (Score:4, Interesting)
Re:just wondering (Score:2)
Damm you Roy. G. Biv. for not fulfilling my dreams.
Re:just wondering (Score:3, Interesting)
fortunately, since moving to the midwest (Kansas City) and seeing the sun set over flat land instead of the mountains where I used to live, I have now seen sunsets with discernable green bands in them. That was my other hope for green.
Now, if I can just witness a green flash [sdsu.edu] sometime....
Re:just wondering about Green Stars. (Score:2)
Want a nice color change in the hearth?
Put a copper tube drilled with holes and stuffed with rubber hose into the fire.
I imagine there might be conditions similar in not so common sequences of stars; perhaps containing the right recipe of elements?
No doubt some stellar race has already toyed with the idea.
So maybe there would be purple plants under a Green Star?
Re:just wondering (Score:2, Interesting)
Re:just wondering (Score:2, Interesting)
Re:just wondering (Score:5, Informative)
If I may be lazy and just give you a URL:
http://www.astronomynotes.com/evolutn/s5.ht
Re:just wondering (Score:2)
I'd mod that up if I had some in the can.
Re:just wondering (Score:3, Funny)
Yes, but only if it gets lots of sleep [slashdot.org].
Re:Yes! (Score:2)
As in, she has pulsated, but outside the hydrostatic equilibrium
Re:just wondering (Score:4, Informative)
Why wouldn't these huge starts turn into black holes? This URL may help you [slashdot.org]
According to the web site: A star of 15 solar masses exhausts its hydrogen in about one-thousandth the lifetime of our sun. It proceeds through the red giant [slashdot.org] phase, but when it reaches the triple-alpha process [slashdot.org] of nuclear fusion [slashdot.org], it continues to burn for a time and expands to an even larger volume. The much brighter, but still reddened star is called a red supergiant. Betelgeuse [slashdot.org], at the shoulder of Orion, is the best-known example. Absolute luminosities may reach -10 magnitude [slashdot.org] compared to +5 for our sun.
Some of these supergiants are unstable and form the very important Cepheid variables. In their final stages, supergiants may explode into supernovae [slashdot.org]. The collapse of these massive stars may produce a neutron star [slashdot.org] or a black hole [slashdot.org].
Re:just wondering (Score:2)
**hides face in shame**
Re:just wondering (Score:4, Informative)
Black Hole FAQ [berkeley.edu]
And on a side note, it's been a long time since I've watched my DVD of "The Black Hole", so I may have to do that now
N.
Re:just wondering (Score:5, Funny)
For a detailed example of supernovae -> black hole, click here [suprnova.org].
Re:just wondering (Score:3, Informative)
Stars don't become black holes until they burn up their fuel, collapsing (and perhaps exploding, perhaps even multiple times) in on themselves until they are much more dense than any visible stars. Then, assuming they they haven't blown off so much of their mass that they no longer have enough mass and will instead become a dwarf or a neutron star, they can collapse to become a black hole.
Link: HOW BLACK HOLES ARE FORMED [geocities.com]
Re:just wondering (Score:4, Informative)
You might want to check university pages, not just some guy's geocities page.
Stars collapse once the core has exhausted its available fuel. This is only a minute fraction of the star's total mass, but it's critical. When the core goes dark the rest of the star falls on it.
According to an article in Discover magazine a few years ago, parts of the star will fall towards the center with a speed as high as a third of the speed of light! This causes enormous pressure, during the "big crunch" the density of the star may be 5-6 higher than the density of a neutron star. IIRC the massive neutrino flux is produced at this time. BTW this "core" is substantially far larger than the core mentioned earlier.
Matter can't be compressed this hard for long and the core "bounces" back. That is what flings the outer layers of the star into space. But force goes both ways - what throws stellar masses into space also increases the pressure on the remaining core. If the density gets too high a black hole is created and it quickly consumes the core, but the outer layers have already been ejected. Otherwise the core eventually bounces back entirely and you have a neutron star. A neutron star is a core of degenerate matter covered by a layer of normal matter.
You do not get cycles of explosions.
(I seem to recall hearing about flares on neutron stars after enough normal mass has fallen to trigger fusion, but those flares are fall smaller than supernovas.)
Re:just wondering (Score:2)
More info for the non-physics folk... (Score:5, Informative)
While these stars are big, filling a large volume of space, the article doesn't mention their mass. This is the ultimate determinant of what becomes a black hole and what doesn't.
Stars have gravity trying to pull everything into the center off it's mass. In physics pressure is basically equal to temapture, so as all the mass is squezed together, it heats up and begins nuclear fission. This creates a lot of heat, and the star's mass tries to expand. Gravity and pressure find a happy meidum and that is how the star ends up a particular size.
As the star burns it's fuel, it has to get hotter or it will stop 'burning', due to the way nuclear fusion works. Eventually it will burn up its fuel and prssure will not balance gravity, and the whole star will collapse. If it is really heavy, say several times the mass of the sun, it will probably collapse into a black hole. If it is slightly heavier than our sun, it might end up as a very dense neutron star. Otherwise, it will end up as a white dwarf, a small star that is somewhat like a ember left over after a campfire. If a star is really massive it can also explode in a supernova to lose some weight and avoid becomming a black whole.
As I mentioned, the article doesn't say what the mass of the star is, but it's probably a safe bet that is above the black hole limit. When it finishes burining its fuel, it will likely go supernova and/or become a black hole.
Re:More info for the non-physics folk... (Score:3, Informative)
a) Turning into a black hole is determined by
mass/radius ratio. You could even turn out sun
into a black hole by "somehow" (
its radius below the Schwarzschild radius.
b) "it heats up and begins nuclear fission."
-> You mean "fusion", as fusion needs heated-up
gas (plasma) to start. Fission is what happens
in nuclear power plants
Re:More info for the non-physics folk... (Score:2)
Here is another question: let's say that we have a star that is 50% hollow at its center, i.e. there is an empty sphere around its center with its radius being at 50% of the radius of the star.
Would the star still collapse towards its center?
Re:just wondering (Score:5, Insightful)
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.
Re:just wondering (Score:2)
Not very dense (Score:3, Insightful)
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
Re:just wondering (Score:3, Informative)
Correct.
> probably just as dense (if not denser
Incorrect, both in the sense of mean density and in the sense of the density of most of the star.
> they are much, much hotter
Incorrect.
> the bigger a star is, the hotter it must be to
> equilibriate
The more massive a star is. Not bigger. The discussion is big in terms in volume. And it's only hotter while it's on the main sequence/during the hydrogen burning phase.
> contrary to what you might expect, the bigger a
>
Visible black holes? (Score:2)
Re:Visible black holes? (Score:2, Insightful)
Re:Visible black holes? (Score:3, Informative)
Re:Visible black holes? (Score:2)
No, it couldn't.
Re:Visible black holes? (Score:3, Insightful)
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 l
Re:Visible black holes? (Score:2)
Re:Visible black holes? (Score:2)
However these supergiant reds are several orders of magnitude to small IIRC.
For what he suggested the central mass would likely be a few dozen times that of the milky way if not the local cluster.
If Stphen Hawkins is a
I'd like to announce the official... (Score:5, Funny)
Go.
Re:I'd like to announce the official... (Score:2)
All links go to photos...
Conchata Ferrell [imdb.com]
Mo'Nique [imdb.com]
Lori Beth Denberg [imdb.com]
- Greg
Re:I'd like to announce the official... (Score:2)
Kirsty Alley [sho.com] Why oh why Kirsty? I can't believe I had impure thoughts for you in my youth.
Rosie ODonnell [talkaboutpeople.com] Somebody I'd want to steer clear of, unfortunately that means driving around the block. Maybe when they staple her stomach they can do the mouth too.
Margaret Cho [bigfatblog.com]. Good to know that Fatkins is working for her. Not funny, but yet the Cho goes on.
Scientists have confirmed it. These are three big fat stars.
Sigh (Score:2)
Re:Sigh (Score:2)
My only wish (Score:3, Funny)
Re:My only wish (Score:3, Funny)
Re:My only wish (Score:3, Funny)
Re:My only wish (Score:3, Informative)
Re:My only wish (Score:2)
Re:My only wish (Score:2)
No. Must have a magnitude of at least -5. Or is that at most -5? Something like Supernova 1006 would be good.
Re:My only wish (Score:2)
Nah, it's a lot less than that (Score:2)
Re:My only wish (Score:2)
Re:My only wish (Score:2)
But there is always Eta Carinae to hope for.
You lack ambition... (Score:2)
Supernova frequency (Score:2)
Re:My only wish (Score:2)
Of course if it happens in our lifetime we won't have to deal with*, and hopefully those that do will get the dysonsphere's force shields up soon enough.
* Unless it's REALLY close, in witch case we still won't have to deal with, we won't even know it. just a bright flash and it's all over.
Mycroft
Re:My only wish (Score:2)
Aparently he became quite skilled at it and was finding quite a few each year.
The reason we don't see them is they are too far away
Re:My only wish (Score:2)
Re:My only wish (Score:2)
That's what sucks about the idea of interstellar exploration. The rest of the universe might already have blown up, and we wouldn't know it until we got there.
Betelguese! Betelguese! Betelguese! (Score:3, Interesting)
Anyone heard ahything that way?
I've heard anything from tomorrow afternoon to 2 milion years. I've heard it's been getting increasingly variable since 1940.
If it goes supernova (and it's WAY big enough) what would be the results here? Genetic disorders? Extinction? Has anyone done the math on this?
RS
No worry -- the world will not end (Score:5, Informative)
Besides, hypothetically, even if it were to explode like a supernova, it won't affect us much. Here is the number:
d = distance to the closest giant (5200light-yr)
E = total energy arising from supernova (1e51erg or something like that)
The energy receied at the Earth is
E / (4 *pi *d*d).
Now compare this number with the energy we receive every second from the Sun:
E_sun / (4 * pi * r*r)
where r is the distance between the Earth and the Sun (1.5e13 cm). You do the math, then the ratio of these two quantities comes out to be:
[E/(4*pi*d*d)] / [E_sun/(4*pi*r*r)] ~ 2.4
So all we get from this supernova is about 2 seconds worth of energy received from the Sun. And I'll tell you that the actual energy received from the supernova is much, much smaller.
Re:Betelguese! Betelguese! Betelguese! (Score:2)
The short story goes like this: The pulse of gamma radiation completely wiped out the ozone layer, and replaced it by an opaque layer of nitrous oxide. That is, opaque but not to UV. So most living being on the surface _and_ in shallow water got deep fried by the Sun's UV. (UV goes a long way through water.) Additionally, that brown shell around the atmosphere caused
Re:Betelguese! Betelguese! Betelguese! (Score:2)
By that logic, niether is Betelgeuse. It's a collection of objects: atoms. The atoms are themselves collections of objects: neutrons, protons and electrons. The neutrons and protons are collections of quarks.
There's always some fool out there putting arbitrary limits on things, making artificial distinctions and generally talking nonsense.
Re:Betelguese! Betelguese! Betelguese! (Score:2)
Non Red Giants (Score:3, Interesting)
Re:Non Red Giants (Score:4, Informative)
Re:Non Red Giants (Score:3, Informative)
ApJ article (1993): Our Sun III [harvard.edu]
Oh gosh, I referenced ApJ in
Re:Non Red Giants (Score:3, Funny)
Pfffft, good riddance I say.
Saturn too... (Score:2, Informative)
Imagine a cluster of stars... (Score:2, Funny)
Poor use of language, 10 yard penalty. (Score:2)
Biggest?
Are we talking about diameter, magnitude or mass?
My guess, from reading the article, is diameter. I'd be interested in the highest mass stars, since there is an inverse relationship between mass and lifetime. What's the shortest time that a star can exist for?
Re:Poor use of language, 10 yard penalty. (Score:2)
Re:Poor use of language, 10 yard penalty. (Score:2)
Which is larger? 1 mole of O2 or 22.4 liters of O2? Note that I didn't specify the temperature and pressure.
Re:Poor use of language, 10 yard penalty. (Score:2)
A real astronomer considers it to be an ambiguous question.
it's largest in dimensions (Score:2)
The article appears to be speaking about diameter.
If you're keen to find out about stars with the largest mass, you could start with Eta Carinae [seds.org]. It's extremely massive and unstable, and came to everyone's attention when it was noticed to be rapidly fluctuating in brightness over the past hundred or so years. It's also close enough that there's arguably a theoretical possibility that we could be in danger if it decides to go any time soon, although it's probably not worth worrying about. Not from a
Re:it's largest in dimensions (Score:2)
Largest? (Score:3, Interesting)
(Well definetly not cooler)
Re:Largest? (Score:2, Funny)
What the hell? You act like the universe is your backyard sandbox. What's out there is what's out there. Sure it would be cool if we found a 3 foot tall leprichan that could shoot fireballs out of his ass running around on mars but it's just not going to happen buddy.
<retard>Wouldn't it be cooler though? </retard>
And for god sakes who modded him up?
Re:Largest? (Score:2)
If they were located in the same place (Score:5, Funny)
Shows what little they know. If they were located in the same place as our own Sun, Jupiter would burn up and not have an orbit!
We must name one of them... (Score:2)
Not km, miles. (Score:2)
And dang, you'd expect the BBC to keep their units right.
Artists Rendition (Score:2)
Wrong Units (Score:4, Funny)
Re:Wrong Units (Score:2)
earth (Score:2)
plenty resources, more than enough land, so no reason to fight over that and the internet spanning earth would be BIGGGGGG
Re:earth (Score:2)
Thanks for the tip! (Score:3, Funny)
If they were located in the same place as our own Sun - at the centre of the Solar System...
So that's where I left it!
Yotta Years...Smoke and Mirrors? (Score:2)
I'm sure there may not be many anomalies between us and 9800ly, however, it would be smart to keep an open mind about the possibility.
Sounds like they are making some progress
"With close stars, scientists can calculate stellar sizes from their temperatures and luminosities."
So does this formula not work for distances beyond say 1,000,000ly?
Where is the transition and why?
01/14/04 Blog 4: -- You Are Here -- SpaceCanada.org [spacescience.ca]
UOM: The Orbit of Jupiter (Score:2)
You heard it here first.
As far as I know.
Solist! (Score:5, Funny)
Re:Solist! (Score:2)
Re:solar system? (Score:2)
Re:solar system? (Score:2, Offtopic)
Re:Farther than the orbit of Jupiter (Score:2)
Re:Farther than the orbit of Jupiter (Score:2, Informative)
For Americans: (Score:2)
Re:For Americans: (Score:2)
Re:Britney, Maddona, Streisand (Score:2)
Re:Catch .22 (Score:2)
What happens when we turn on that quantum walkie talkie?
Will the future tell us what change it needs in the past?
Terra forming Mars would be a breeze if we could steer comets into its path.
http://science.slashdot.org/article.pl?sid=05/0
Re:Catch .22 (Score:2)
NASA provides a yearly list of spinoff products [nasa.gov] Also NASA doesn't have to create a new product that everybody buys to be useful. Better understanding of materials, new measurement techniques, or even new ways to model systems, all have practical benifits. The average person on the street may not care, but design or manufacturin
Re:Big planets... (Score:3, Informative)
I doubt that there's much of a correlation between larger stars and larger planets orbiting them. The tricky thing about extrasolar astronomy is that we simply can't detect "normal" (i.e. non-gas-giant, although their prevalence might say that gas giants are actually normal, and rocky planets like the earth are maybe unusual) planets around other stars right now.
As far as I know, extra