Rocky Planets May Form Around Most Sun-like Stars
Written by Nancy Atkinson
Astronomers have found numerous Jupiter-like planets orbiting other stars. But because of the limits of our current technology, they haven’t yet found any other terrestrial Earth-like planets out in the universe. But new findings from the Spitzer Space Telescope suggest that terrestrial planets might form around many, if not most, of the nearby sun-like stars in our galaxy. So perhaps, other worlds with the potential for life might be more common than we thought.
A group of astronomers led by Michael Meyer of the University of Tucson, Arizona used Spitzer to survey six sets of stars with masses comparable to our sun, and grouped them by age. "We wanted to study the evolution of the gas and dust around stars similar to the sun and compare the results with what we think the solar system looked like at earlier stages during its evolution," Meyer said. Our sun is about 4.6 billion years old.
They found that at least 20 percent, and possibly as many as 60 percent, of stars similar to the sun are candidates for forming rocky planets.
The Spitzer telescope does not detect planets directly. Instead, using its infrared capability, it detects dust — the rubble left over from collisions as planets form — at a range of infrared wavelengths. Because dust closer to the star is hotter than dust farther from the star, the "warm" dust indicates material orbiting the star at distances comparable to the distance between Earth and Jupiter.
Meyer said that about 10 to 20 percent of the stars in the four youngest age groups shows “warm� dust, but not in stars older than 300 million years. That is comparable to the theoretical models of our own solar system, which suggests that Earth formed over a span of 10 to 50 million years from collisions between smaller bodies.
But the numbers are vague on how many stars are actually forming planets because there's more than one way to interpret the Spitzer data. "An optimistic scenario would suggest that the biggest, most massive disks would undergo the runaway collision process first and assemble their planets quickly. That's what we could be seeing in the youngest stars. Their disks live hard and die young, shining brightly early on, then fading," Meyer said.
"However, smaller, less massive disks will light up later. Planet formation in this case is delayed because there are fewer particles to collide with each other."
If this is correct and the most massive disks form their planets first and then the smaller disks take 10 to 100 times longer, then up to 62 percent of the surveyed stars have formed, or may be forming, planets. "The correct answer probably lies somewhere between the pessimistic case of less than 20 percent and optimistic case of more than 60 percent," Meyer said.
In October 2007, another group of astronomers used similar Spitzer data to observe the formation of a star system 424 light-years away, with another possible Earth-like planet being created.
More definitive data on formation of rocky planets will come with the launch the Kepler mission in 2009, which will search to find if terrestrial planets like Earth could be common around stars like the sun.
Original News Source: JPL Press Release
Filed under: Extrasolar Planets
February 18th, 2008 at 8:07 pm
Wow! maybe if we destroy our planet, we can go to some of the other ones around the universe. I hope we don't destroy those ones!
February 19th, 2008 at 12:32 am
This is incredible news, but I'm sure it will stir up many different communities/groups of people, mostly the very religious community. With each new discovery, our uniqueness becomes less, as our properties that we once believe we absolutely perfect and unique could perhaps become uniform and common. I can't speak for anyone else, but I personally think this is astounding news, and can't wait for the next big discovery, even at risk of our uniqueness. That uniqueness will probably still exist, though, as I'm sure we won't see humans on a planet 10 light years away. I believe the next big step will be finding these terrestrial planets that have formed, then, as technology advances, study them as we can.
February 19th, 2008 at 2:30 am
you're right to be worried about religion. the creationists & religious right will probably try to block any research that shows life
February 19th, 2008 at 6:29 am
Religion and Science can co-exist. More progressive religions are tolerant of science albeit wary of natural selection theory. The more fundamentalist the religion the more intolerant it is of science since they take the approach that scripture is literally God's spoken word. Of course since most scripture predates modern science, there is no mention of scientific principles. Hence the reason most fundamentalist religious sects are retroactice in their views of how the world should be. The more progressive and mature religious viewpoint is that scripture are parables written by human beings doing their best to interpret the word of God with the limited knowledge available to them at the time they wrote them, and with the implicit understanding that the meaning of at least some of their original text has been changed by numerous translations into many different languages over the centuries.
February 19th, 2008 at 7:18 am
Aliens are not mentioned in the Bible.
Neither are cats.
Fundamentalism is dangerous and oppressive.
BTT:
I think rocky planets are probably very common, but I also think that the chances of finding goldilocks planets with O2 atospheres is remote, and finding life is even more remote.
I don't think ET life would necessarily look anything like life on earth. It may not be based on the same chemical compounds. In fact, we may not even recognize life when we find it.
Still, we need to look.
February 19th, 2008 at 9:11 am
We'll know life when we see it. Life is organized. Life is purposeful.
Some of the earliest life forms still survive on Earth…even if on another world they progress to ethereal, energy beings, there will still be the early life that we'll recognize. And finding those worlds is just around the corner. I just hope I'm around when the first probe sends back the images! Nanu, nanu!
February 19th, 2008 at 9:12 am
To Paul Glasgow
I don't know about other religions but Muslims already believe in creations beyond humans and they are called Jins. They live in another dimension then ours and you can read more about it here http://muttaqun.com/jinn.html.
Just trying to spread knowledge
Umar Chaudhry
February 19th, 2008 at 3:09 pm
I think that life will be found to be widespread in this galaxy at least. Many other systems in the galaxy may already be seeded with primitive earth organisms ejected into interstellar space by impacts billions of years ago. Finding oxygen rich planets which would imply photosynthesizing organisms live there is much less likely. Finding intelligent life wold be difficult and finding space faring civilizations in this galaxy will probably be a long shot.