Those wacky Extrasolar Planets

General physics and astronomy discussions not directly related to Celestia
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Apollo7
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Those wacky Extrasolar Planets

Post #1by Apollo7 » 16.07.2003, 21:40

Ok so most of us are aware that up to now about 120 extra solar planets are known, most of which are around main sequence stars with a few exceptions (i.e. Pulsar Planets).

Now each discovery is an indirect one as we know and while they stirr the imagination we really do not know all that much about each individual planet we find. Now One thing is for certain the current techniques of finding worlds do lend themselves to revealing massive planets in unusual orbits (epistellar jovians, eccentric jovians and the like).

So one might argue that the samples of planets we are getting are not, at the moment, status quo.

Our own solar system seems very much more refined and orderly compared to systems like 55 Cancri, in which 3 very massive jovian worlds occupy close-in and eccentric type orbits around there star. The question that hampers me is, is our solar system an abbaration or the norm?

There is no doubt that universe is replete with planets, this is not a point which we shall debate. The questions I would pose are thus, if our planetary system is the abbaration, why did we end up this way, why don't we have 3 jupiter mass behemoths with eccentricities of .46 tearing their way through the inner solar system? What makes us special. On the other hand if our system is the norm and our current techniques only allow us to discover the remarkable and unusual, then how common might systems like ours be?

Consider these facts, current techniques only allow finding planets down to around Saturns mass (last I checked anyway). Consider the masses of our Jovian planets, Jupiter - 318 E, Saturn - 95 E, Uranus 14 E, Neptune 17 E. This makes Saturn roughly 30% of Jupiter's mass, with Uranus weighing in at 4.4% and Neptune at 5.3%. For comparison Earth is a mere .31% of a Jupiter mass.

So many planets lie beneath the detection threshold as is, I think this implies that orderly "by the book" systems will go largely undetected. While the amazing and intriguing systems will be detected. What are some other opinions on this matter. Is the Terran system a freak of nature or the model?
"May Fortune Favor the Foolish" - James T. Kirk

Rassilon
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Post #2by Rassilon » 16.07.2003, 21:50

I base this solely on intuition that our system is the only one like it...I feel there is alot of random elements in the dispersion of planets...No system will be alike...neither will any of the alternate terrain planets we will discover in the centuries to come...

The conclusion most scientist base that we are the only life in our universe is only because we havent found other life yet...well none sentient...

Also goes hand in hand with the discovery of terrian planets...When it does happen it will be the greatest discovery for mankind...not for me...I already believe there are other terrian planets out there ;) Including life...
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Apollo7
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Post #3by Apollo7 » 16.07.2003, 22:42

It seems logical that all systems would be unique, just as its logical that all life would be different as it developes under different circumstances.

I also agree that the Universe is full of life, the real problem is communication over long distances and the fact that only so many societies will actually have interstellar travel capability.

The one thing that really irritates me about "real" scientists is the annoying propensity to dismiss anything which is not currently supported by evidence. I've always taken the oposite view that if its not disproven its still possible. This may not be "good science" but its how I operate (my own views are part of the reason why I put off pursuing a degree in a science for so long).

Anyway, I'm looking forward to the upcoming interferometer missions which should dramatically improve our ability to detect planets around other stars.
"May Fortune Favor the Foolish" - James T. Kirk

abiogenesis
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Post #4by abiogenesis » 17.07.2003, 01:34

Apollo7 wrote:I've always taken the oposite view that if its not disproven its still possible.


True, absence of proof is not proof of absence. However, there are fundamental problems with denying the importance of evidence.

I consider myself a "positivist". That is, if the theory fits observation, it is useful. If it doesn't, it isn't. Belief in spite of evidence is, obviously, folly. I claim that belief without evidence is equally so. If there is no evidence there can be no objective discussion. There can be no science.

I wouldn't say that scientists "dismiss" out of hand these ideas, it's just that without any evidence one way or the other there is nothing to discuss. I think scientists are doing an exceptional job of collecting and evaluating the evidence available. We are constantly developing new technologies and methods to collect even more evidence.

Speculation has it's place (this forum, for instance :wink: ), and it is invaluable in formulating new theories which can then be tested. As long as it is followed by scientific inquiry and the search for evidence. A theory that cannot be tested is useless to science. That is the fundamental difference between science and philosophy.

- a b i o g e n e s i s -

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Apollo7
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Post #5by Apollo7 » 17.07.2003, 02:39

well I've never claimed myself to be a scientist and even if I aquire advanced degrees I may still prefer the role of philosopher, and that is my perogotive.

However, to clarify, many things are believed in quite fully without evidence (try god), although its logical to assume (in my mind) that if imperfection exists, that perfection must also exist, it is by no means proof of god.

I for one tend to not trust everything NASA says, some would claim this to be folly, but, NASA is a political entity and I tend to be very cynical about government. Sure there is no proof that people in NASA lie, but I have reason to be suspicious. I guess as always there are those darn grey areas that we all must live with.

Besides I rarely need to prove anything to anybody, I'm confidant in my belief and thats all I need, hence my love of Astronomy melds two (mutually incompatable/to some) ideaologies as philosophy and science, but it is what it is. :)

Thanks for the reply.
"May Fortune Favor the Foolish" - James T. Kirk

Don. Edwards
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Post #6by Don. Edwards » 17.07.2003, 02:59

Well the HD 28185 system is fairly similar to ours in many respects so far. Ok it doesn't seem to have terrestrial planets in orbit in the habitable zone. But there is a massive 5 times Jupiter mass gas-giant orbiting in a stable circular Earth like orbit in the same region Earth orbits around our sun. That puts it smack in the middle of HD 28185’s habitable zone. Now seeing just how prevalent moons and gas-giant planets go hand in hand we don't necessarily have to look for terrestrial planets orbiting just there parent star but also orbiting there massive parent planet as well. Our solar system has planet size moons orbiting our biggest gas-giant so you can imagine the size of the moons that could be orbiting a gas-giant with many times the mass of Jupiter. If the gas-giant was able to gather most of the heavier elements in the beginning of the systems birth it lends that the moons/satellites got there share of heavy elements as well. If we find in fact that Europa does harbor an under ice ocean, this bodes well for finding bigger and similar worlds in orbit of other gas-giants that are in a stable orbit in the habitable zone of there star. Now what we need to do is to see if we can detect any kind of a wobble in the orbit of the gas-giant that may indicate that it has a nice size moon orbiting it. I know that this is years away at this point but it might be easier to find big moons around those planets than to find single terrestrial planets orbiting out there by themselves. Just a thought anyway.

Don.
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