Skip to comments.Giant Planets 'Formed In Hundreds Of Years'
Posted on 11/28/2002 4:41:17 PM PST by blam
Giant planets 'formed in hundreds of years'
Giant planets like Jupiter were formed in just a few hundred years, not several million as was previously thought, according to scientists.
The research completely contradicts the widely held assumption that it takes at least one million years for gas giant planets like Jupiter and Saturn to evolve.
Two years of work by scientists using a greatly refined mathematical model produced results that they say explain just how quickly such planets form.
Astrophysicist Thomas Quinn, from the University of Washington, said the disk of matter which spins round a young star begins to break up and congeal into planets more quickly than earlier thought.
The gravity of the resulting clusters of matter pulls in surrounding gas that makes up the vapour shrouds around giant planets like Jupiter, he told the journal Science.
"If a gas giant planet can't form quickly, it probably won't form at all," he said.
Scientists believe gas giants to be quite common, after finding evidence for about 100 planets of up to 10 times the size of Jupiter around other stars.
According to the research, the new mathematical model also explains why Uranus and Neptune do not have gas "envelopes".
The research team argued that when these more distant planets were formed, the solar system was still part of a star cluster and other nearby stars moved away, causing whatever gas the planets had to disperse.
Story filed: 19:01 Thursday 28th November 2002
Isn't that close to the size of our sun? In any case 10 times the size of Jupiter is a big-ass planet.
There is some info out there about how much bigger Jupiter would have to be to turn into a star.
One wonders if these results can be extrapolated to the time required for stellar formation.....
Roughly speaking, Jupiter is 300 times the mass of the Earth. The sun is 300,000 times the mass of the Earth, or about 1,000 times the mass of Jupiter.
As best I recall, stars don't form unless the mass is at least 0.1 solar masses (and maybe even bigger), so a minimum stellar mass would be about 30,000 times the mass of the earth, which would be 10 times larger than a planet with a mass of ten Jupiters.....
That makes Jupiter too small to be a star by a factor of about 100....
Objects that are slightly too small to initiate fusion reactions and become full fledged stars are called "brown Dwarfs"... a google search will probably tell much more than I can about them....
Sloppy journalism here. What is meant? 10 times the MASS? 10 times the DIAMETER? I'm guessing mass; diameter wouldn't probably reach 10 times Jupiter's without increasing the mass past the "brown dwarf" threshold.
Excluding the Sun, Jupiter contains the majority of known mass in the Solar System. But it still is way too small (low-mass) to have initiated fusion in its core: it's only .001 solar masses! The estimates vary; I've heard that Jupiter would have to be around 80 times its current mass to "turn on" as a very small red dwarf. Anything 10-70 Jupiter masses would be a "brown dwarf", glowing in the visible spectrum from residual heat.
Care to prove global warming anyone?
The problem with fast condensation is where the kinetic energy of all the original primordial particles in the condensing cloud goes. The usual model says that you have to radiate it away slowly as particles fall into the gravity well and heat things up.
At any given time, you have a near-equilibrium between the pull of gravity on the masses and the outward pressure of the hot gas. This "equilibrium" is dynamic and allows further collapse as the residual heat shines itself away. The usual thinking says that if you somehow force the cloud together faster than it can get rid of the energy in this way, it just blows apart again.
The article doesn't really say why the fast collapse works and how the primordial energy is dissipated. I certainly can't guess.
Well..okay then..., so what's your point?
It's used this way: "At one time, people believed that [insert old theory here]. We now know that [insert new theory here]."
Makes you wonder, what are we going to "know" tomorrow that will change what we "now know" into what we "once believed"?
I have heard the same petuniasevan.
KAY: Any given time, around fifteen hundred landed aliens are on the planet, the majority right here in Manhattan. Most aliens are decent enough, just trying to make a living.
EDWARDS: Cab drivers?
KAY: Not as many as you'd think. Humans, for the most part, don't have a clue. Don't want one, either. They're happy. They think they've got a pretty good bead on things.
EDWARDS: Why the big secret? People are smart, they can handle it.
KAY: A person is smart. People are dumb. Everything they've ever "known" has been proven to be wrong. A thousand years ago everybody knew as a fact, that the earth was the center of the universe. Five hundred years ago, they knew it was flat. Fifteen minutes ago, you knew we humans were alone on it. Imagine what you'll know tomorrow.
EDWARDS: So what's the catch?
You're too kind; I'm just marking time with my post until some of the big guns drop by to really fill in the details.