Subtitle: "An abundance of medium-sized worlds is challenging planet-formation models."
doi:10.1038/480302a
Posted on 12/17/2011 4:48:48 PM PST by SunkenCiv
NASA's Kepler space telescope... has identified 2,326 candidate planets, nearly doubling its haul since February.
But what has puzzled observers and theorists so far is the high proportion of planets -- roughly one-third to one-half -- that are bigger than Earth but smaller than Neptune... Their very existence upsets conventional models of planetary formation and, furthermore, most of them are in tight orbits around their host star, precisely where the modellers say they shouldn't be.
"It poses a challenge," says Douglas Lin, a planet-formation modeller and director of the Kavli Institute for Astronomy and Astrophysics at Peking University in Beijing, China. "You can't just tweak the parameters. You need to think about the physics."
Guided by the example of our own Solar System, with its distinct sets of large and small worlds, early planet-formation models were based on the notion of 'core accretion'. Dust swirling around a star in a protoplanetary disk can aggregate into small planetesimals of rock and ice, which collide and stick together. The inner part of the disk contains too little material for these cores to grow much bigger than Earth. But farther out, they can attain ten Earth masses or more, enough to attract a vast volume of gas and become Jupiter-like.
The detection, starting in 1995, of Jupiter-sized planets with orbits as short as a few Earth days contradicted these models. The theorists revised their models to allow these 'hot Jupiters' to form far from their star and then migrate in.
(Excerpt) Read more at nature.com ...
doi:10.1038/480302a
Planets coalesce out of dust swirling around their parent stars -- but where super-Earths form is unclear. [M. Garlick/SPL]
Gas giants credited for solar system formationJupiter and Saturn form the basis of a "grand unified theory" of the solar system, according to new computer simulations. The research traces three seemingly unrelated phenomena - the giant planets' orbits, craters on the Moon, and the behaviour of certain asteroids - to the motions of the two gas giants nearly four billion years ago... an international team of researchers has performed computer simulations that reproduce the orbits of the four giant planets - Jupiter, Saturn, Uranus, and Neptune - in exquisite detail. The team has published a trio of papers about their findings in Nature. In the model, the four planets form in 10 million years within the current orbit of Uranus. Surrounding them in a ring are several thousand rocky objects called planetesimals, left over from the formation of the planets... planetesimals begin to "leak" into the giant planet zone and the orbits of the giant planets gradually change. After 700 million years, Saturn has migrated outward and Jupiter inward to the extent that they reach a "resonance" point. This means they begin to march in lockstep with each other, with Jupiter completing two orbits around the Sun for every one of Saturn's. The resonance allows the pair to greatly disturb the orbits of the other planets.
by Maggie McKee
25 May 2005
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Super headache is right, forget ‘theorists’.
Merry Christmas, see ya next yr...
Their models are wrong? I mean challenged. Maybe they should just make up favorable data like climate change models. I think man forgets his place in the universe.
As the technology gets better the more we find out we don’t know.
I’d be interesting in knowing what percentage of these unexpected planets are orbiting single stars like our sun which is in a minority.
“You can’t just tweak the parameters. You need to think about the physics.”
No, really? LOL!
If you find a planet like earth with life , but is 100 times larger ,would the life forms be 100 times larger also ?
“Their very existence upsets conventional models of planetary formation and, furthermore, most of them are in tight orbits around their host star, precisely where the modellers say they shouldn’t be.”
They likely migrated inward.
It just shows that solar systems are like snowflakes, and ours may be a thankfully placid freak.
They’d likely be smaller due to stronger gravitational effects.
I’d be willing to bet that as soon as techniques improve enough we’ll see chart on post #1 fill out to a solid blob.
In other words, the current techniques are good at finding large planets, and close planets, and low and behold, that’s what we see in the chart!
probably smaller- the gravity would be too intense for 100 times larger
There is a very good chance that it would be large like the dinosaurs as the massive Earth might have a greater gravitational pull.
But their could just as easily be “normal” sized critters if their skeletons are made of stronger stuff than ours.
Really pretty awe inspiring when you realize how many planets we’ve found around so few stars and most are only large planets we can detect.
The gravity on such a large planet could be similar to earths. Gravitational attraction is a function of mass and diameter; if the density of the planet is low, a huge planet could have surface gravity similar to our own.
The gravity on such a large planet could be similar to earths. Gravitational attraction is a function of mass and diameter; if the density of the planet is low, a huge planet could have surface gravity similar to our own.
If God can create the universe, he can create billions of other planets with life if he pleases and he isn’t required to tell me about it.
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