Planets May Form in Hundreds, Not Millions, of Years

Seanasy writes "Recent simulations on the Pittsburgh Supercomputing Center's Terascale Computing System suggest that planet formation may take a lot less time than previously thought. The results were published in SCIENCE."

Comments

Correction: gas giants & abstract

[MacAndrew]

The study actually looked at gas giants like Jupiter and Saturn. My understanding is that these planets formed by scooping up gas as they orbited the sun. The interior rocky planets of the inner disk probably took longer to achieve final shape, though their materials would have been the first to cool into solid form.

Neat stuff.

Here's the Science abstract:

A Quickie Birth for Jupiters and Saturns
Richard A. Kerr

On page 1756, a group of astrophysicists presents computer simulations of the nascent solar system that suggest a possible mechanism for the formation of the gas giant planets: runaway fluctuations in the density of the protoplanetary disk. In their model, gas giants of about the right size, number, and orbit condense from a disk of gas to look like very young Jupiters. The trick was to simulate the process in fine detail so that the gas's own gravity could take over.

Full Text

More abstract

[MacAndrew]

Odd, they have a different abstract from the summary. Sorry, I don't have a full subscription to Science.... not that I would blow their copyright and post it here. :)

To wit:

Formation of Giant Planets by Fragmentation of Protoplanetary Disks

Lucio Mayer,1*dagger Thomas Quinn,1* James Wadsley,2 Joachim Stadel3dagger

The evolution of gravitationally unstable protoplanetary gaseous disks has been studied with the use of three-dimensional smoothed particle hydrodynamics simulations with unprecedented resolution. We have considered disks with initial masses and temperature profiles consistent with those inferred for the protosolar nebula and for other protoplanetary disks. We show that long-lasting, self-gravitating protoplanets arise after a few disk orbital periods if cooling is efficient enough to maintain the temperature close to 50 K. The resulting bodies have masses and orbital eccentricities similar to those of detected extrasolar planets.

1 Department of Astronomy, University of Washington, Seattle, WA 98195, USA.
2 Department of Physics & Astronomy, McMaster University, 1280 Main St. West, Hamilton, ON L8S 4M1, Canada.
3 University of Victoria, Department of Physics and Astronomy, 3800 Finnerty Road, Elliot Building, Victoria, BC V8W 3PG, Canada.
* To whom correspondence should be addressed. E-mail: lucio@physik.unizh.ch, trq@astro.washington.edu

dagger Present address: Institute of Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.

PSC

[Hadean]

Here's a direct link to PSC's article, which does -not- require registration (bah).

As mentioned by another post, we're talking about "Jupiter-like" gas giants, not Earths. The reason it can't take millions of years: "The problem with [the current model], however, is that if the formation process takes too long, nearby stars will, in effect, boil off the gas envelope."

Re:PSC

[Hadean]

Oops, for some reason I didn't realize there already was a direct link... Ah well, here's a copy of it in case it gets Slashdotted (gotta have a real reason to reply, right?):

"Planets May Form Faster than Scientists Thought"

Simulations at Pittsburgh Supercomputing Center show that planets can form in hundreds of years.

PITTSBURGH, December 11, 2002 -- Taking advantage of the computing capability of LeMieux, the Pittsburgh Supercomputing Center's terascale system, scientists have determined that large, Jupiter-like planets -- similar to those observed outside Earth's solar system -- can form in dramatically shorter periods of time than previously thought.

The findings, published in SCIENCE (Nov. 29), challenge accepted thinking that it takes millions of years for such planets to form from the pancake-shaped nebula of gas and dust swirling around young stars.

"We used a new model of planet formation," said University of Washington astrophysicist Thomas Quinn, who led the research team, "that couldn't adequately be tested without this kind of computing power, and we found that these giant planets can form in hundreds of years, rather than the millions that the standard model predicts."

Using LeMieux, the most powerful system in the United States committed to public research, the researchers carried out a series of planet formation simulations. Because of LeMieux, the researchers were able to include roughly ten times more detail than previous similar work, and this increased resolution led directly to the new findings.

Nearly 100 extrasolar planets have been detected within the past decade, with masses that range from roughly the size of Jupiter to ten times larger. These discoveries prompted thinking about how large planets, similar to Jupiter and Saturn, form. Called gas giant planets, these planets have most of their mass in a gaseous envelope that surrounds the solid core.

The standard model holds that a core of solid matter congeals from the swirling disk -- called a protoplanetary disk -- around young stars, a process thought to take a million years or so, with another million to ten million years to accumulate the gaseous envelope. The problem with this model, however, is that if the formation process takes too long, nearby stars will, in effect, boil off the gas envelope. "If a gas giant planet can't form quickly," said Quinn, "it probably won't form at all."

An alternative model holds that giant planets form directly from instabilities in the protoplanetary gas, without the need for a solid-matter core. Until the recent simulations, this model hadn't produced convincing results. "The main criticism," said Quinn, "was that this model wasn't ready. Nobody was making predictions with it. But that's because they didn't have enough computational horsepower."

The recent simulations -- using 30,000 processor hours on LeMieux -- produced a distribution of masses and orbits comparable to observed extrasolar planets. According to the astronomical findings since the mid-1990s, these gas giant planets appear to be fairly common. "If these planets can't form quickly," says Quinn, "they should be a relatively rare phenomenon, and if they form according to this mechanism they should be relatively common."

Authors of the research, besides Quinn, are Lucio Mayer, a former University of Washington post-doctoral researcher who recently joined the University of Zurich, James Wadsley of McMaster University, Ontario, Canada and Joachim Stadel at the University of Victoria, British Columbia, Canada.

Established with an August 2000 grant from the National Science Foundation, LeMieux comprises over 3,000 Compaq Alpha EV68 processors, providing over six teraflops (six trillion calculations a second) of computational capability to U.S. engineers and scientists.

The Pittsburgh Supercomputing Center is a joint effort of Carnegie Mellon University and the University of Pittsburgh together with the Westinghouse Electric Company. It was established in 1986 and is supported by several federal agencies, the Commonwealth of Pennsylvania and private industry.

Re:This isn't at all surprising

[MacAndrew]

This is a troll, right?

God made the Earth about 6000 years ago so it couldn't have formed in millions of years.

Interesting logic. In other words, "Because CONCLUSION, then QUESTION must lead to CONCLUSION." I believe this is called a syllogism.

I don't care if oil forms in ten minutes, the Earth is not 6,000 years old to a 99.9% level of certainty unless God has a very odd sense of humor (possible). Personally I'm leaning towards 4.5 billion years.

Seriously, in defense of Christianity, and I am agnostic, scant few Christians subscribe to creationism or intelligent design, so whatever you may believe be careful not to stereotype Christians based on it.

Velikovsky (and James P. Hogan) would be pleased!

[TrebleJunkie]

Wow. And to think that Velikovsky was just about run out of the scientific community 50 years ago for putting forth a similar idea, among others -- that planets could form rather quickly, in years or hundreds of years, rather than the millions of years previously thought.

This is also sort of the subject of James P. Hogan's novel, Cradle of Saturn. If you've never read James P. Hogan, you should. Good, good stuff.

Re:This isn't at all surprising

[MacAndrew]

Unremarkably, you miss that the study suggests the gas giants formed quickly not recently.

6,000 years is a lot more reasonable-sounding ... why? A staggering amount of evidence point towards a time period much, much longer. "Reasonable" is believing things in reasonable accord with the evidence, and the estimate need never be completely proved to be accepted as fact. That's just not how people do things in real life.

Evolution, for that matter, is a fact under the same principle of overwhelming evidence. The debate or theory now centers on how it happened, which might be Darwin's theory or something else; if Darwin is disproved the fact of evolution will remain. You are free to believe otherwise, but won't change the real world any more than your refusal to believe in the fact of gravity will enable you to fly.

Is this disrespectful? Yes. I think it would be untenable to grant any belief a held by any person person with equal weight. I thought creationism, with its tenuous basis in the Bible, had been left by the wayside long ago, though I realize there will always be a core that will believe anything.

Sure, but...

[Myco]

It takes much longer to get the fjords just right.

Understanding the "hot Jupiters"

[Drog]

For anyone interested in more details, this story appeared here a week ago. An interesting comment pointed out that this theory has major implications in understanding the hundred or so "hot Jupiters" that have been found around other stars. Most have orbital periods of only a few days and orbit their star at a distance less than Mercury's. This new theory may suggest that hot Jupiters are actually newly-formed gas planets and perhaps even a transient phenomena.

Re:This isn't at all surprising

[dvdeug]

The earth couldn't be millions of years old because God created it about 6000 years ago. If the creation of the earth about 6000 years ago is accepted as truth, then we use this to eliminate the question of the age of the earth being 4.5 billion of year old.

If we start with the assumption that the world is 6000 years old, then given that assumption, it's 6000 years old. If you start without any assumption of Christianity's truth, it looks like the world is roughly 5 billion years old. If you start by assuming the Bible is true, and the information of our senses is true, then you have a fairly complex question, with different answers depending on the believer.

it is impossible to be a true Christian and not believe that God created the world.

No where in the Bible does it say the world was created 6000 years ago. I think the Bible has pretty good evidence that the Hebrews didn't view large numbers with the precision we did - notice the symbolic use of 70, 70 times 70, and 144,000 at various places in the bible. It would have been very hard to explain to them that the world was five billion years old. Christians* believe God created the world; but they don't necessarily believe that he felt compelled to give the exact blow by blow to the Hebrews, instead of giving them some version they could understand.

* Well, most Christians, at least.