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Dusty Clues: Study suggests no dearth of Earths
by Science News
Thanks to SPS for the link.
Reposted from:
http://www.sciencenews.org/articles/20080202/fob2.asp
Ron Cowen
Supposedly, there's no place like home. But a new study suggests that earthlike planets orbit or are forming around many, if not most, nearby sunlike stars, providing places where life might have gained a foothold.
HOME AWAY FROM HOME. Artist's depiction of an earthlike planet orbiting a star outside the solar system.
NASA/JPL-Caltech
That conclusion comes from an infrared survey of some 300 stars similar in mass to the sun and ranging in age from a youthful 3 million years to a middle-aged 3 billion. Using NASA's Spitzer Space Telescope, Mike Meyer of the University of Arizona in Tucson and his colleagues surveyed those stars and their surroundings at an infrared wavelength of 24 µm. In many cases more radiation was emitted than the stars themselves could have produced, indicating the presence of dust. That may in turn be a sign of possible terrestrial planet formation, Meyer and his colleagues, including Lynne Hillenbrand and John Carpenter of the California Institute of Technology in Pasadena, argue in the Feb. 1 Astrophysical Journal Letters.
Dust, along with gas and ice, exists in the disks that form around newborn stars. Those materials gradually coalesce into large clumps that stick together to form planets, asteroids, and comets, and in the process the original disks disappear. Around older stars, however, dust can be generated by rocky bodies—fledgling planets or asteroids—crashing into each other. In either case, the dust absorbs visible and ultraviolet light from its parent star and reradiates it at infrared wavelengths.
The infrared radiation recorded by Spitzer indicates that most of the dust is warm, with a temperature of some 100 to 300 kelvins. In our solar system, that temperature range corresponds to a location anywhere from Earth's distance from the sun to that of Saturn. That includes the inner solar system's asteroid belt.
About 10 percent of the sunlike stars examined by Meyer's team have dust radiating at 24 µm. Because a system with forming or mature planets may not emit strongly at 24 µm throughout its life, the fraction of stars with planets could be higher than 10 percent. In fact, the researchers estimate that up to 62 percent of the surveyed systems could have planet-making material in their inner regions, where any water present might remain liquid.
"Meyer's result is exciting confirmation that around many other stars like our sun, the region analogous to our own asteroid belt is full of solid material, possibly related to past or present planet formation," comments Caltech astronomer Charles Beichman, who is not a member of the team. The finding "is a good sign that the basic stuff of planetary systems is widespread."
The numbers calculated by Meyer and his colleagues "are still pretty soft" but jibe with the notion that it is easier to make rocky planets like Earth than gas giants like Jupiter, says theorist Alan Boss of the Carnegie Institution of Washington (D.C.).
According to a leading model, rocky cores coalesce first. To make a Jupiter, the core then has only about 10 million years to snare vast amounts of gas from the planet-forming disk before that structure disappears. In contrast, to form a terrestrial planet, the rocky core need grow only to about the size of Earth's moon before the disk vanishes. The core can then leisurely accumulate bits of leftover rock and dust to build up to a body as large as Mars or Earth, says Boss.
Although the Spitzer findings are tantalizing, Meyer notes that proof of terrestrial exoplanets awaits the launch next year of the Kepler mission, which will search for such orbs by the tiny dip in starlight they induce each time they pass in front of their parent stars.
If you have a comment on this article that you would like considered for publication in Science News, send it to editors@sciencenews.org. Please include your name and location.
Reposted from:
http://www.sciencenews.org/articles/20080202/fob2.asp
Ron Cowen
Supposedly, there's no place like home. But a new study suggests that earthlike planets orbit or are forming around many, if not most, nearby sunlike stars, providing places where life might have gained a foothold.
HOME AWAY FROM HOME. Artist's depiction of an earthlike planet orbiting a star outside the solar system.
NASA/JPL-Caltech
That conclusion comes from an infrared survey of some 300 stars similar in mass to the sun and ranging in age from a youthful 3 million years to a middle-aged 3 billion. Using NASA's Spitzer Space Telescope, Mike Meyer of the University of Arizona in Tucson and his colleagues surveyed those stars and their surroundings at an infrared wavelength of 24 µm. In many cases more radiation was emitted than the stars themselves could have produced, indicating the presence of dust. That may in turn be a sign of possible terrestrial planet formation, Meyer and his colleagues, including Lynne Hillenbrand and John Carpenter of the California Institute of Technology in Pasadena, argue in the Feb. 1 Astrophysical Journal Letters.
Dust, along with gas and ice, exists in the disks that form around newborn stars. Those materials gradually coalesce into large clumps that stick together to form planets, asteroids, and comets, and in the process the original disks disappear. Around older stars, however, dust can be generated by rocky bodies—fledgling planets or asteroids—crashing into each other. In either case, the dust absorbs visible and ultraviolet light from its parent star and reradiates it at infrared wavelengths.
The infrared radiation recorded by Spitzer indicates that most of the dust is warm, with a temperature of some 100 to 300 kelvins. In our solar system, that temperature range corresponds to a location anywhere from Earth's distance from the sun to that of Saturn. That includes the inner solar system's asteroid belt.
About 10 percent of the sunlike stars examined by Meyer's team have dust radiating at 24 µm. Because a system with forming or mature planets may not emit strongly at 24 µm throughout its life, the fraction of stars with planets could be higher than 10 percent. In fact, the researchers estimate that up to 62 percent of the surveyed systems could have planet-making material in their inner regions, where any water present might remain liquid.
"Meyer's result is exciting confirmation that around many other stars like our sun, the region analogous to our own asteroid belt is full of solid material, possibly related to past or present planet formation," comments Caltech astronomer Charles Beichman, who is not a member of the team. The finding "is a good sign that the basic stuff of planetary systems is widespread."
The numbers calculated by Meyer and his colleagues "are still pretty soft" but jibe with the notion that it is easier to make rocky planets like Earth than gas giants like Jupiter, says theorist Alan Boss of the Carnegie Institution of Washington (D.C.).
According to a leading model, rocky cores coalesce first. To make a Jupiter, the core then has only about 10 million years to snare vast amounts of gas from the planet-forming disk before that structure disappears. In contrast, to form a terrestrial planet, the rocky core need grow only to about the size of Earth's moon before the disk vanishes. The core can then leisurely accumulate bits of leftover rock and dust to build up to a body as large as Mars or Earth, says Boss.
Although the Spitzer findings are tantalizing, Meyer notes that proof of terrestrial exoplanets awaits the launch next year of the Kepler mission, which will search for such orbs by the tiny dip in starlight they induce each time they pass in front of their parent stars.
If you have a comment on this article that you would like considered for publication in Science News, send it to editors@sciencenews.org. Please include your name and location.
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Posted: Monday, February 4, 2008 | PermalinkComments 1 - 43 of 43 |
Reload Comments | Back to Top | Page Numbers2. Comment #122117 by Goldy on February 4, 2008 at 7:18 pm
Maybe God got bored with Earth - or the other gods are in competition! ;-)Other Comments by Goldy
3. Comment #122119 by Serdan on February 4, 2008 at 7:20 pm
Why am I not surprised?Every time man says "I'm special", he most likely is not.
Other Comments by Serdan
4. Comment #122123 by cjnkns on February 4, 2008 at 7:24 pm
While this is interesting - I really don't' find it enlightening... I guess I kind of figured this was the way it was anyway.
There are just far to many stars and planets for humans to even comprehend. How can we even believe that our meager calculations are sufficient.
Life is everywhere just because we can barely get our minds and bodies of this one little rock means nothing.
Other Comments by cjnkns
5. Comment #122153 by hoops mccann on February 4, 2008 at 8:25 pm
This is awfully inferential. I also noticed that the journalist reached conclusions that the author of the study was very cautious about making. Hate it when they do that. It's better than the usual wild guesses though. Other Comments by hoops mccann
6. Comment #122179 by mmurray on February 4, 2008 at 9:20 pm
Why do some people regard it as obvious that because there are so many stars life must exist elsewhere? You can only draw that conclusion if you know the odds of planets and life forming and we don't. None of the available evidence we have including these results contradicts the hypothesis that we are the only planet with life on it in the whole universe. All we have so far is the suggestion that planets are not unusual, based on observation, but no evidence that earth like planets are common. Even if missions like Kepler tell us earth like planets in the habitable zone are other there the evidence of our own solar system suggests that planets without life are more common than those with. We can't even find microbes on the other planets in our solar system. Michael
Other Comments by mmurray
7. Comment #122181 by Spinoza on February 4, 2008 at 9:28 pm
Life is everywhere
... uh, we don't know that
Other Comments by Spinoza
8. Comment #122194 by GBile on February 4, 2008 at 10:31 pm
Just think of the millions of 'Holy Books' out there.But then again: thousands of Carl Sagans ? Sounds good.
Other Comments by GBile
9. Comment #122204 by sarah95 on February 4, 2008 at 11:18 pm
This sounds pretty interesting...not an earth-shattering(pardon the pun) breakthrough, but definitely giving exiting hints. I wish Carl Sagan were still around to comment on developments like this. Other Comments by sarah95
10. Comment #122234 by Laurie Fraser on February 5, 2008 at 12:48 am
Forget the "Holy Books" and Carl Sagans, GBile, what about the millions of Kylie Minogues? (Puts on best Brando-like growl: "The horror!") Other Comments by Laurie Fraser
11. Comment #122237 by PJG on February 5, 2008 at 12:56 am
Of course, just because life (as we know it Captain) may be possible on other planets - and life supporting planets are a statistical probability given the numbers involved - it still doesn't mean life is there (abiogenesis being uncertain - we might be the only planets where it all came together at the right moment!) and so the theists can still cry "we're special".
My guess is that, should life be found elsewhere, they would still say "God made life on other planets but only HUMAN life on Earth" and if intelligent life were found elsewhere, they would STILL claim something like "Well, that is why God made the universe so BIG... so he could seed it with other planets and other life."
The problem is that any discovery is just a snap-shot in time. If they can't understand the concept of evolution (and the timescales involved) and therefore don't accept that it is an ongoing process, they can still claim that "Goddidit".
P.S. That is interesting - "abiogenesis" is not in the spellchecker but "Goddidit" is! :o)
Other Comments by PJG
12. Comment #122244 by eggplantbren on February 5, 2008 at 1:56 am
" 7. Comment #122179 by mmurray on February 4, 2008 at 9:20 pmavatarWhy do some people regard it as obvious that because there are so many stars life must exist elsewhere? You can only draw that conclusion if you know the odds of planets and life forming and we don't. None of the available evidence we have including these results contradicts the hypothesis that we are the only planet with life on it in the whole universe"
mmurray is right about this. We do not have very much knowledge about the range of conditions under which life can form, and how much luck is needed. Still, a lot of these results could have gone the other way. Extra-solar planets *could* have been rare. But they're not. Complex molecules could have been rare in the universe. But they're not. And so on. A lot of terms in the Drake Equation have been found to be fairly high as our knowledge has increased, but that one about abiogenesis is still massively uncertain, and probably also the one about eventually evolving intelligent life.
Other Comments by eggplantbren
13. Comment #122251 by Laurie Fraser on February 5, 2008 at 2:26 am
Correct, eggplantbren (may I call you egg?) - it is nigh impossible to calculate the occurrence of abiogenesis. We are simply suffering from a complete lack of data. (For example, even within our own solar system we have yet to find extra-terrestrial organic material that even looks like coming anywhere near the conditions for molecules to spontaneously reproduce.)
Stacked against that, though, is the inductive power of sheer numbers. Of course, as Hume pointed out, no inductive reasoning is "truth-forming", but with 10 to the power of 25 or so stars out there, one would need to be a real pessimist not to even admit to the possibilty that a few would have earth-like planets winging around them.
And wouldn't that be wonderful? How would Pat Robertson rationalise that one?
Other Comments by Laurie Fraser
14. Comment #122255 by LorienRyan on February 5, 2008 at 2:39 am
"How would Pat Robertson rationalise that one?"
Probably by sending pamphlets with a suggested donation.
Other Comments by LorienRyan
15. Comment #122257 by Laurie Fraser on February 5, 2008 at 2:44 am
I'll send him an iguana. No, on second thought, that would be cruelty to animals. A hajib, then. Other Comments by Laurie Fraser
16. Comment #122260 by Steve Zara on February 5, 2008 at 2:58 am
Pat Robertson rationalise that one?
"Pat Roberston" ... "rationalise"
No, sorry, don't get it.
Other Comments by Steve Zara
17. Comment #122261 by LorienRyan on February 5, 2008 at 2:58 am
Well, it was the Mormons according to Rowan Atkinson - so we could send him a transcript of Romney's 'Address to the Galactic Senate.' Other Comments by LorienRyan
18. Comment #122263 by LorienRyan on February 5, 2008 at 3:08 am
Apologies - 'it was the Jews who were right' according to Atkinson.
Welcome to Hell: Rowan Atkinson
http://www.youtube.com/watch?v=XFGrQMD6Uqc
Other Comments by LorienRyan
19. Comment #122264 by epeeist on February 5, 2008 at 3:12 am
Comment #122251 by Laurie Fraser
it is nigh impossible to calculate the occurrence of abiogenesis. We are simply suffering from a complete lack of data. (For example, even within our own solar system we have yet to find extra-terrestrial organic material that even looks like coming anywhere near the conditions for molecules to spontaneously reproduce.)
I came across this http://discovermagazine.com/2008/feb/did-life-evolve-in-ice/article_view?b_start:int=1
Another interesting surface chemistry idea.
As for extra-terrestrial molecules, there are loads out there - http://en.wikipedia.org/wiki/List_of_molecules_in_interstellar_space
Other Comments by epeeist
20. Comment #122266 by LorienRyan on February 5, 2008 at 3:30 am
epeeist,
Great article. I admire Matthew Levy's and Marie Tieche's passion and dedication.
Other Comments by LorienRyan
21. Comment #122270 by healthphysicist on February 5, 2008 at 3:46 am
LorienRyan:Maybe you were first thinking of South Park:
http://www.youtube.com/watch?v=PLnSJo3Z-Iw
Other Comments by healthphysicist
22. Comment #122271 by Laurie Fraser on February 5, 2008 at 3:47 am
Thanks, epeeist - great article. Other Comments by Laurie Fraser
23. Comment #122272 by mmurray on February 5, 2008 at 3:47 am
Continuing on in my depressive vein here is an article about how big the universe is and how it is likely to be impossible to communicate with other sentient beings even if there are some:http://www.space.com/searchforlife/071206-seti-aliens-apart.html
Of course you could hope that dark matter and dark energy allow you some unknown technology. This is a sort of `warp drive of the gaps' approach where you hope any gap in known physics represents something we can turn into an interstellar spacecraft. But the deafening silence from ET and the lack of visits kind of suggests otherwise.
Michael
Other Comments by mmurray
24. Comment #122276 by epeeist on February 5, 2008 at 4:25 am
Comment #122272 by mmurrayContinuing on in my depressive vein here is an article about how big the universe is and how it is likely to be impossible to communicate with other sentient beings even if there are some:Of course there are some. It is just that when they start running short of real estate they turn their solar systems into Dyson spheres.
Other Comments by epeeist
25. Comment #122277 by LorienRyan on February 5, 2008 at 4:28 am
healthyphysicist,
ah yes, lol, memory mix up - I blame it on my misspent youth.
Other Comments by LorienRyan
26. Comment #122278 by Steve Zara on February 5, 2008 at 4:32 am
Of course there are some. It is just that when they start running short of real estate they turn their solar systems into Dyson spheres.
I like the Stephen Baxter/Blood Music idea that rather that expanding outwards, civilizations will expand inwards. Not likely, but a cool idea.
Other Comments by Steve Zara
27. Comment #122280 by Azven on February 5, 2008 at 4:51 am
Was the picture of "an earthlike planet orbiting a star outside the solar system" really necessary? Strangely enough, I know what an Earth-like planet could look like, even (or is that especially) a made up one! Other Comments by Azven
28. Comment #122281 by Quetzalcoatl on February 5, 2008 at 4:59 am
The article is good, if a little inference-heavy. It is already known that in some of the systems where we've detected gas giants there are orbital gaps that might well be filled by smaller rocky worlds. We need some better telescopes! Nasa/JPL/whoever should pull their finger out and get on with it.
Epeeist-
It is just that when they start running short of real estate they turn their solar systems into Dyson spheres.
Not to nitpick, but given the amount of resources that would be required to actually throw a shell around a star, if you're already running low on resources then you've missed the opportunity already.
Other Comments by Quetzalcoatl
29. Comment #122288 by epeeist on February 5, 2008 at 5:45 am
Comment #122281 by QuetzalcoatlNah, all you need is a good project manager. As anyone who has worked on big projects will tell you, you don't actually need anyone who can do anything. You just need lots of project managers ;-)
Not to nitpick, but given the amount of resources that would be required to actually throw a shell around a star, if you're already running low on resources then you've missed the opportunity already.
Other Comments by epeeist
30. Comment #122289 by Tyler Durden on February 5, 2008 at 5:56 am
epeeist,
I agree 100%
I'd elaborate on my point but I have a meeting to attend ;-)
Other Comments by Tyler Durden
31. Comment #122290 by epeeist on February 5, 2008 at 6:03 am
Comment #122289 by Tyler Durden "There are two kinds of people in the world, those who do the work and those who take the credit. Be one of the former, there is less competition."
I agree 100%
I'd elaborate on my point but I have a meeting to attend ;-)
Other Comments by epeeist
32. Comment #122365 by pulsar1z on February 5, 2008 at 8:02 am
The whole purpose of this endeavor is to search the galaxy for conditions like our own solar system. The new telescopes we have and are building will offer new and wondrous information. This is an exciting time for Astronomers and we have added to the human book of knowledge a million fold. In fact it grows by quantum leaps every day thanks to computers. Of course the motivation is to answer the question are we alone? I think that microbial life in the universe is probably not that rare but intelligent life capable of space travel would be very, very, very rare indeed. The existence of a "Creator" capable of designing the whole thing, nonexistent.
Other Comments by pulsar1z
33. Comment #122382 by j.mills on February 5, 2008 at 8:13 am
I agree: however commonplace life may turn out to be, intelligent life looks like an accident as flukey as abiogenesis, greatly diminishing the odds of there being any more. And as Fermi(?) said, "Where is everybody?" Either they're not there or there's no practical way of exploring and traversing the volumes of space and time between us and them.
But it's still all hand-waving! :)
Other Comments by j.mills
34. Comment #122407 by 7Fred7 on February 5, 2008 at 8:36 am
Excellent line of research, and we may look forward to much more like it.Other Comments by 7Fred7
35. Comment #122419 by pulsar1z on February 5, 2008 at 8:46 am
I am not an authority just a thinker but in my opinion, our life spans are too short to travel or even communicate with anything but the closest star systems. As far as we know the speed of light is the fastest anything can travel. At that rate it would hundreds or thousands of years just to get a signal to more than a few of the closest stars.What's exciting though, It might be possible to detect intelligent life. Who knows a signal, (Light or Radio Spectrum) might have been sent to our part of the Galaxy thousands of years ago. With a little luck and good timing we might be able to receive it. If, it still had sufficient strength. Then we could spend the rest of our lives deciphering what it meant.
Forget communicating with another Galaxy. That belongs to the realm of Star Trek
Other Comments by pulsar1z
36. Comment #122539 by pulsar1z on February 5, 2008 at 12:20 pm
This is one of my favorite equationsN = N* fp ne fl fi fc fL
for those who are interested, just google it
Other Comments by pulsar1z
37. Comment #122581 by arogop on February 5, 2008 at 2:00 pm
32. Comment #122290 by epeeist
"There are two kinds of people in the world, those who do the work and those who take the credit. Be one of the former, there is less competition."
Great quote. Is this your creative juices? I want to use it and give credit.
Other Comments by arogop
38. Comment #122733 by Rational_G on February 5, 2008 at 10:32 pm
The probability of planets around most stars keep going up. The probability of earthlike planets keeps going up. So the number of sites where life may exist keeps going up. Pretty soon we will image earth like planets' atmospheres - what if those atmospheres are earth like? What will that suggest? Life throughout the universe is plausible. Radio searches are reasonable. There are answers to Fermi's paradox. It's called the limits to exponential growth. There are probably bacteria on Mars. There may be bacteria on Europa and Enceladus, Perhaps even in the atmosphere of Venus. Intelligent life is a tougher question. We may get lucky with a radio detection some day - modest searching by radio is pretty easy and relatively cheap.We live in interesting times.
Other Comments by Rational_G
39. Comment #122735 by Rational_G on February 5, 2008 at 10:38 pm
A lot of people assert that intelligent life is rare. There's really no way to tell without looking around ie searching for electromagnetic evidence. Other Comments by Rational_G
40. Comment #122746 by epeeist on February 5, 2008 at 11:47 pm
Comment #122581 by arogopIndhira Gandhi
"There are two kinds of people in the world, those who do the work and those who take the credit. Be one of the former, there is less competition."
Great quote. Is this your creative juices? I want to use it and give credit.
Other Comments by epeeist
41. Comment #122753 by jo5ef on February 6, 2008 at 1:01 am
Wow 300 deg K, thats balmy, theres got to be something growing in all that stuff.BTW there are 2 kinds of people in the world, those who think there are 2 kinds of people in the world and those who know better
Other Comments by jo5ef
42. Comment #122820 by j.mills on February 6, 2008 at 6:51 am
Actually there are 10 kinds of people: those who understand binary and those who don't. Other Comments by j.mills
43. Comment #127037 by Dutchie on February 14, 2008 at 6:10 pm
Laurie Fraiser: Or the millions of Tom Cruises! Think about it - all those copyright claims on Youtube, all those South Park episodes, a whole chorus of (rightfully angry) John Sweeneys, and a mass genocide of couches on talkshows . . . cue The Twilight Zone theme!And, GBile: All those Holy Books . . . I can imagine the headlines now:
CONTACT WITH ALIENS MADE. COVENANT OF RELIGIOUS E.T. FACTIONS DECLARE JIHAD ON HERETIC HUMANS.
In all seriousness, it has been a great year for science: the discovery of the newborn planet on 3 January, the discovery of Gliese 581c AND d (what are the porbabilities of TWO earthlike planets formingtogether?), the discovery of bacteria able to survive Venusian temperatures - wow.
This is just another wonderful discovery. It's all happened at the samee time, as if it was meant to. Divine intervention, perhaps . . . ?
Other Comments by Dutchie
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1. Comment #122111 by eggplantbren on February 4, 2008 at 6:58 pm
http://arxiv.org/abs/0712.1057
Other Comments by eggplantbren