Skip to comments.Terrestrial Planets Could be More Common Than Gas Giants
Posted on 06/19/2012 3:36:59 AM PDT by SunkenCiv
Lars Buchhave and his team selected more than 150 stars with known planetary systems that were cataloged by NASA's Kepler mission. They then studied these stars' metal content and the size of the planets in their solar systems. What they found was that gas giant planets were more likely to form around metal rich stars, whereas terrestrial planets were equally likely to form around metal rich or metal poor stars.
As the team explains, the reason for this fits neatly into the "core accretion" model of planetary formation. Each gas giant has a metal core which hydrogen and helium accumulate around. However, if there is no core to collect around, the lighter elements will be blown away by stellar winds while the star is still relatively young. If a star has a high enough metal content, its potential planets might be able to form a large metallic core quickly, before the winds do their work. The core will then gravitationally attract the remaining gas to itself and a new gas giant is born.
On the other hand, the formation of terrestrial planets is not dependent on helium and hydrogen and therefore not subject to the same time constraints. If a star has lower metal content it might take longer to form terrestrial planets, but all the ingredients are still there. Essentially, there is no upper time limit for a terrestrial planet to form whereas a gas giant must develop quickly to keep its hydrogen and helium trapped within the solar system.
(Excerpt) Read more at universetoday.com ...
This artist's conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Credit: University of Copenhagen/Lars Buchhave
Alien Earths Could Form Earlier than ExpectedPrevious studies have shown that Jupiter-sized gas giants tend to form around stars containing more heavy elements than the Sun. However, new research by a team of astronomers found that planets smaller than Neptune are located around a wide variety of stars, including those with fewer heavy elements than the Sun. As a result, rocky worlds like Earth could have formed earlier than expected in the universe's history. "This work suggests that terrestrial worlds could form at almost any time in our galaxy's history," said Smithsonian astronomer David Latham (Harvard-Smithsonian Center for Astrophysics). "You don't need many earlier generations of stars." ...Astronomers call chemical elements heavier than hydrogen and helium "metals." They measure the metal content, or metallicities, of other stars using the Sun as a benchmark. Stars with more heavy elements are considered metal-rich while stars with fewer heavy elements are considered metal-poor... They measured the stars' metallicities and correlated that with the sizes of the associated planets. Large planets tended to orbit stars with solar metallicities or higher. Smaller worlds, though, were found around metal-rich and metal-poor stars alike. "Giant planets prefer metal-rich stars. Little ones don't," explained Latham. They found that terrestrial planets form at a wide range of metallicities, including systems with only one-quarter of the Sun's metal content.
David A. Aguilar & Christine Pulliam
Wednesday, June 13, 2012
Harvard-Smithsonian Center For Astrophysics
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Seems to me that if we’re alone, God has given it to us to explore and populate.
;’) Nicely done! Also IB “it’s only a theory”, “just in it for the grant money”...
And lets not forget the ever popular, “We’ll never be able to go there anyway”.
Even worse is someone who wants to pretend to do the math first, *then* tell us “we’ll never be able to go there anyway”. ;’)
If our new found “planetoid” category counts, then our solar system has more rocky planets than gas giants (4 vs. 5+). So this isn’t that wild a concept.
Invent warp drive, start colonizing!
because of the vast distances between stars, I believe at least one of three things need to be true.
Personally, I hope that all three are possible, and BTW, I want a ZPM to run my motorcycle.
There are lots of Class M planets. They visited a new one almost every week on Star Trek.
They even found a planet on which there was silicon based life, as opposed to the carbon based life found on earth. So there could even be life in forms we wouldn’t think about, such as silicon based life, out there in the cosmos.
Figure out how long it would take to accelerate to 90% of the speed of light at one gravity of constant acceleration.
Then, of course as you approached your destination you would then have to decelerate at one gravity for the same amount of time.
There are a lot of very interesting little understood things going on at the sub atomic level which could potentially be harnessed for our own use.
“Spooky action at a distance” as Einstein called it or quantum entanglement has the potential of communicating instantaneously over billions of light years.
Obviously we aren’t going far right now but that’s what science is for. Its also possible that we simply haven’t stumbled across or conceived of something extremely simple
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