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wstevenbrown
2005-Feb-08, 08:03 PM
The Spitzer site recently posted this account. The question arises whether to call the primary a star or a rogue planet. I would dearly love to know how many of these there are. Look for yourself:

http://www.spitzer.caltech.edu/Media/relea...6/release.shtml (http://www.spitzer.caltech.edu/Media/releases/ssc2005-06/release.shtml)

Further on was this:

http://www.spitzer.caltech.edu/Media/relea...c2005-06c.shtml (http://www.spitzer.caltech.edu/Media/releases/ssc2005-06/ssc2005-06c.shtml)

Fraser
2005-Feb-08, 09:14 PM
SUMMARY: NASA's Spitzer Space Telescope has found the dusty disc of planetary material surrounding an extremely low-mass brown dwarf. The failed star, called OTS 44, is only 15 times the mass of Jupiter, and is located 500 light-years away in the Chamaeleon constellation. Previously, the smallest brown dwarf known to have such a disc was twice as massive. Astronomers are now wondering if a habitable world could form around such a small, dim dwarf.

View full article (http://www.universetoday.com/am/publish/mini_solar_system.html)

What do you think about this story? Post your comments below.

Tiny
2005-Feb-08, 09:20 PM
Begging Nasa to send an signal to that place and see what kind of responses we can have? Just kidding. Wanna guess how many inner planets exist in the mini solar system? 3. :ph34r:

bossman20081
2005-Feb-08, 10:20 PM
Aren't there bigger planets than that? I think I recall reading that there are extra-solar planets bigger than that. So it could be a rogue plant instead of a star....

Guest_david
2005-Feb-08, 11:56 PM
I have been thinking about Titan,that is when our sun becomes a brown dwarf.Would that place Titan in a position to give live a foothold?Are there any models of this point in time?David

w_croft
2005-Feb-09, 01:49 AM
Could it not be that we are witnessing the beginnings of a star and solar system, perhaps this is how they start out. A mass of space dust around a central large nucleii that could just be or be gathered together over time. Gravity would pull the dust in and larger masses that are circling the central point or asteroids that are caught by the central masses gravity gather this dust themselves also, thus becoming planets in the process?

The larger central mass could pull all of the dust towards it and the smaller masses circling around having smaller gravitational pull only collect the mass as they impact with it, thus eventually as most of the mass gathers at the central point inevitably it heats up due to friction or something until eventually it fires up and becomes a full blown star.

My thought.... perhaps a brown dwarf system is just a baby system that one day will grow up. :)

alfchemist
2005-Feb-09, 03:58 AM
Hi, w_croft! There's this mass limit or critical mass for the pressure in the core of the protostar to be enough to ignite the hydrogen in the core and become a real star. In the case of brown dwarf, I think the accretion process has already ceased

w_croft
2005-Feb-09, 06:27 AM
I don't know about the accretion having stopped. A lot of what we have is conjecture and theory, which is exactly what I'm putting forward too, conjecture and theory! ;)

I think the central nucleii holds the biggest gravitational pull in the system so it's not entirely out there to think that it's still pulling in mass.

I figure that the dust surrounding it is still trapped by the gravitational pull from the star, therefore it may still be drawing in some mass and since it can take billions of years for a solar system to form that's plenty of time for even the smallest amount of accretion to build up immensely over time.

Once it was ignited though I would then also expect solar winds from the star to blow the dust away but the picture didn't seem to show that this had occurred either.

What if there is a point to which a star needs to grow before the gravitational pull is negated by the solar winds. I can only assume the solar winds get more powerful the bigger a star gets so who's to say they don't ignite before accumulating all of their mass. Isn't the Sun meant to be slowly swallowing the Earth, scheduled for billions of years away?

Duane
2005-Feb-09, 06:06 PM
Astronomers are now wondering if a habitable world could form around such a small, dim dwarf.

I wonder how close the life zone would be to this star, as well as how long the star will produce enough heat to keep a life zone stable for the billions of years it would take for complicated life forms (ie, more complex than bacteria) to evolve.

alfchemist
2005-Feb-10, 04:53 AM
Hi Croft! The thing about ignition at the core at extremely high temperature (3million degrees) is not conjecture or theory. Precisely why you can reproduce the fusion-based bombs even if you have fussion-based primary. While it is true that nuclear fusion could take place in a brown dwarf, it cannot sustain it. Since we are talking about accretion resulting in the formation of a star, the dusty disk cannot provide enough fuel for the brown dwarf unless you break them down again to gaseous elements which would require lots of energy. Accreting a good part of the dusty disk to get enough mass is one thing. Transforming these materials into fussionable form is another

alfchemist
2005-Feb-10, 04:54 AM
....fission-based primary...

w_croft
2005-Feb-10, 06:05 AM
Contrare, most of what is accepted theory today is or was conjecture and guestimates at best in the past. A lot of accepted theory has never been proved scientifically.

Nature is perfect but not so predictable that we can say that at a set temperature (3 million degrees) in the core of a star it will ignite. We have never witnessed the point at which a star ignites nor do we have any instrument capable of measuring the temperatures at which you talk of. It is merely theory involving calculations of equations all of which can not be tested at a 3 million degrees temperature. The easy way to tell it is merely a guess is the fact it is such a nice round number.

All fuels do have an ignition point dependent on composition and other factors such as pressure. Pressure changes alone can cause combustion in fuels, it happens in car engines, so who is to say on the grand scale of things at the levels of stars that it can't happen under the enormous pressure alone that gravity provides? The compression of the materials under the weight of the gravity will heat them up.

In fact I'd like to ask another question, no one has ever been able to even answer for me before. The question of what precisely is gravity? Now before anyone jumps the gun, I'm not asking what does gravity do, I know what gravity does, I am merely asking what exactly is gravity? There is no answer to it because we do not understand exactly what gravity actually is, we only understand how it affects things and until we know why gravity does what it does we'll never understand what it actually is.

John L
2005-Feb-10, 02:59 PM
Originally posted by Duane@Feb 9 2005, 12:06 PM

Astronomers are now wondering if a habitable world could form around such a small, dim dwarf.

I wonder how close the life zone would be to this star, as well as how long the star will produce enough heat to keep a life zone stable for the billions of years it would take for complicated life forms (ie, more complex than bacteria) to evolve.
Brown Dwarf stars don't emit visible light, but infrared. I think the life zone would be pretty close into the BD, though, so it would probably be tidally locked, and any life would have to be able to photosynthesize with IR light, but it should be possible.

Dave Mitsky
2005-Feb-10, 03:27 PM
Originally posted by Guest_david@Feb 8 2005, 11:56 PM
I have been thinking about Titan,that is when our sun becomes a brown dwarf.Would that place Titan in a position to give live a foothold?Are there any models of this point in time?David
Did you mean when the Sun becomes a red giant (and after that a planetary nebula and a white dwarf)? A brown dwarf is a failed star with a mass of approximately 13 to 75 times that of Jupiter (about 1 to 7 or 8% that of the Sun) and is not part of the evolution of main sequence stars like the Sun.

http://astron.berkeley.edu/~basri/bdwarfs/contents.htm

Dave Mitsky

GOURDHEAD
2005-Feb-10, 04:42 PM
Now before anyone jumps the gun, I'm not asking what does gravity do, I know what gravity does, I am merely asking what exactly is gravity? Geometry.

antoniseb
2005-Feb-10, 05:05 PM
I'd like to point out that a planet may form around a brown dwarf, and it may be heated by the IR, and dim optical light coming from the brown dwarf, but there is a problem for life forming because the radiant outpouring from the brown dwarf will decrease continuously, making it difficult for life to establish a niche that will work for the great durations.

alfchemist
2005-Feb-11, 06:08 AM
That's interesting, John L! Brown dwarf emitting infrared? In case creatures evolve with eyes, they would have IR sensor! Does that mean it would be easier to find a brown dwarf if you're using an IR detecting device or telescope?

Hi, Antoniseb! I guess that depends on the rate of decrease in radiant output. life, if has gotten a foothold, would adapt if the change isn't so drastic. Could you give us some numbers on this?

bigbluestar
2005-Feb-11, 04:14 PM
Ok this is for w_croft. The brown dwarf is a failed star not because it can't egnite because of pressure. Its a failed star because the building blocks have ran out. Basically what determins a stars size and all stars for that matter is the environment in wich it accreted all its matter. If there were enough mass to create a O type star then that is what you would get. The accretion for this star stoped because there we nothing really left to accrete. The mass that is currently around the star is not enough to change the class of this object. The material around it is in stable orbit so they will be there for a long time until the themselfes clump together and form planets. For all intensive purpose the star failed because its too small and does not have the required mass and pressure (a direct correlation with the mass) to sustain fission. In other words if it were to lets stay fission as you suggested it will not last long... it will eventually stop reaction and just become a big firecracker. not as burning engines as other stars are.... :)

alfchemist
2005-Feb-11, 06:04 PM
Hi bigbluestar! w_croft is hoping materials will accrete but even if they do, they are not fussion fuel, are they?

Duane
2005-Feb-11, 08:26 PM
Originally posted by alfchemist@Feb 11 2005, 11:04 AM
Hi bigbluestar! w_croft is hoping materials will accrete but even if they do, they are not fussion fuel, are they?
No, not the stuff currently in orbit.

alfchemist
2005-Feb-12, 02:32 PM
So, that requires far greater energy to break them down into fussion fuel which is not available in this system

w_croft
2005-Feb-14, 05:58 AM
My thoughts extend to a theory that it doesn't really matter what matter is around to start with, just that with a large enough gravitational force it could break down any heavier compounds or even elements into lighter elements and thus into fuel suitable for a star.

You might all be thinking I'm crackers that I'm talking about Alchemy, changing Pb into Au and all that. Which in a way yes I am, but it has been proven here on Earth already that elements can be stripped of electrons, protons and neutrons and in doing so change what an element is with enough force applied.

Aren't all stars composed primarily of H and He? Both H and He are extremely simple elements, so don't you ever think that perhaps a reason for this composition is that heavier elements can't hold together under the kinds of pressures exerted by gravitational forces that large and are subsequently broken apart over time? If indeed that was the case then a larger mass system with a higher gravitational force would reach the correct composition and ignition point sooner, that's why my suggestion about the brown dwarf star, smaller system and therefore longer process.

It's not difficult to think that a smaller mass could just mean a much slower accretion process which I think is supported by the fact that all of the matter hasn't been accreted to the star nor the planets surrounding it yet. Our solar system which is a larger system has already done this. As matter isn't created out of nothing, this suggests strongly to me that it has been forming a system very slowly there for a long time unless the system has been getting fed matter from somewhere external. The thought that it could have gathered there from an external source seems more ludicrous to me because then you'd have to say it came from somewhere and then I would expect a much greater volume of matter. If you want to say it came from another system then I would ask how? Where is the closest system and how would it travel so far, also it's a very small system as it is and therefore it has less gravitational force to pull material from another system.

It is really not such a big step from here to say that perhaps it is yet to reach its point where the star ignites even if it is on a smaller scale.

Remember that a bigger fire burns a larger amount of fuel and usually in a much quicker time and as all stars burn out eventually so too would a brown dwarf regardless of how long it took. No star is a self sustaining unit nor ever could be.

alfchemist
2005-Feb-14, 10:28 AM
Hi, w_croft! i'm the alfchemist here. Pls don't take that distinction away from me! :D First of all, you're proposing an alternative theory and there's a place for that here, where you could get a lot of response in such a short time! :D Second, The gravitational force in that system is not enough to break down nucleons and I guess, in any system for that matter. If you're talking about spontaneous nuclear reactions occuring here on earth, well, they are not fusion and cannot initiate fusion by themselves. Third, stars are born out of these light elements. These elements are not there because of the star. Stars can fuse lighter elements to make heavier elements and not the reverse process. I'll stop here and hopefully, others will add more...

Essel
2005-Feb-14, 01:27 PM
Pls see the following:

How brown are dwarfs (http://etacha.as.arizona.edu/~eem/exo/caveats.html)

The Basics of BDs (http://www.darkstar1.co.uk/cosmicastbro.htm)

w_croft, no one is still sure of how was sol born but one thing is sure it has more than 99% of the matter of the solar system. It was surely born in a violent environment, may be born somewhere else and then thrown out. No one is sure but we tend to accept what appears logical.

Think of Why is Jupiter radiating - becasuse it is shrinking by 7 centimeters in a year? When will it stop shrinking and radiating?

I agree we know little about start birth but it gives comfort to know that even brown drwarfs can sustain a habitable environ.

alfchemist
2005-Feb-14, 03:46 PM
Btw, w_croft, in neutron stars, gravity is so great that protons and electrons combine to form neutron. Though you might deem this to be breaking down of atoms, this is more of a death than birth of a regular star

zephyr46
2005-Feb-16, 01:04 AM
It was interesting to read about the smallest planet found so far

PSR B1257+12 (http://news.bbc.co.uk/1/hi/sci/tech/4264603.stm?from=astrowire.com), does it again, one of the first pulsars found to have planets, one of the first multiple planetary systems ( Three planets (http://www.extrasolar.net/) ), now at a Extra Solar Planets conference in Aspen :


The orbit of the new planet is close to the average distance from our Sun to the asteroid belt.

The planet is about 1 1/5 the size of Pluto!

The planet is called a Comet (http://www.extrasolar.net/) in the Extrasolar visions website.

alfchemist
2005-Feb-19, 06:19 AM
It looks like we will know very soon if our solar system is unique or just the common type. From the data, gas giant-star system seems common but that is changing now because of the new findings