Stanford: Galaxy May Swarm with 'Nomad Planets'

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Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by bystander » Sat Feb 25, 2012 7:06 pm

Researchers say galaxy may swarm with 'nomad planets'
Kavli Institute for Particle Astrophysics and Cosmology (KIPAC)
Stanford University | Andy Freeberg | 2012 Feb 23
Our galaxy may be awash in homeless planets, wandering through space instead of orbiting a star.
In fact, there may be 100,000 times more "nomad planets" in the Milky Way than stars, according to a new study by researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of Stanford University and the SLAC National Accelerator Laboratory.

If observations confirm the estimate, this new class of celestial objects will affect current theories of planet formation and could change our understanding of the origin and abundance of life.

"If any of these nomad planets are big enough to have a thick atmosphere, they could have trapped enough heat for bacterial life to exist," said Louis Strigari, leader of the team that reported the result in a paper submitted to the Monthly Notices of the Royal Astronomical Society. Although nomad planets don't bask in the warmth of a star, they may generate heat through internal radioactive decay and tectonic activity.

Searches over the past two decades have identified more than 500 planets outside our solar system, almost all of which orbit stars. Last year, researchers detected about a dozen nomad planets, using a technique called gravitational microlensing, which looks for stars whose light is momentarily refocused by the gravity of passing planets.

The research produced evidence that roughly two nomads exist for every typical, so-called main-sequence star in our galaxy. The new study estimates that nomads may be up to 50,000 times more common than that.

To arrive at what Strigari himself called "an astronomical number," the KIPAC team took into account the known gravitational pull of the Milky Way galaxy, the amount of matter available to make such objects and how that matter might divvy itself up into objects ranging from the size of Pluto to larger than Jupiter. Not an easy task, considering no one is quite sure how these bodies form. According to Strigari, some were probably ejected from solar systems, but research indicates that not all of them could have formed in that fashion.

"To paraphrase Dorothy from The Wizard of Oz, if correct, this extrapolation implies that we are not in Kansas anymore, and in fact we never were in Kansas," said Alan Boss of the Carnegie Institution for Science, author of The Crowded Universe: The Search for Living Planets, who was not involved in the research. "The universe is riddled with unseen planetary-mass objects that we are just now able to detect."

A good count, especially of the smaller objects, will have to wait for the next generation of big survey telescopes, especially the space-based Wide-Field Infrared Survey Telescope and the ground-based Large Synoptic Survey Telescope, both set to begin operation in the early 2020s.

A confirmation of the estimate could lend credence to another possibility mentioned in the paper – that as nomad planets roam their starry pastures, collisions could scatter their microbial flocks to seed life elsewhere.

"Few areas of science have excited as much popular and professional interest in recent times as the prevalence of life in the universe," said co-author and KIPAC Director Roger Blandford. "What is wonderful is that we can now start to address this question quantitatively by seeking more of these erstwhile planets and asteroids wandering through interstellar space, and then speculate about hitchhiking bugs."

Nomads of the Galaxy - Louis E. Strigari, Matteo Barnabe, Philip J. Marshall, Roger D. Blandford
‘Island-Hopping’ to the Stars
Centauri Dreams | Paul Gilster | 2012 Feb 13

‘Nomad’ Planets Could Outnumber Stars 100,000 to 1
Universe Today | Nancy Atkinson | 2012 Feb 23

Nomad Planets Roam Our Galaxy
Discovery News | Irene Klotz | 2012 Feb 24
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by orin stepanek » Sat Feb 25, 2012 11:03 pm

I like the idea of nomad planets roaming the galaxy! There may be some between galaxies also. :wink: Just think; if a star captures one it will be like an adoption of sorts and add to the star's family of planets. :D With all the rocks orbiting the sun; I'm sure that someday we will realize there are worlds all over the galaxy1 :)
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by neufer » Sat Feb 25, 2012 11:22 pm

orin stepanek wrote:I like the idea of nomad planets roaming the galaxy! There may be some between galaxies also. :wink: Just think; if a star captures one it will be like an adoption of sorts and add to the star's family of planets. :D With all the rocks orbiting the sun; I'm sure that someday we will realize there are worlds all over the galaxy1 :)
But 100,000 per star :!:

Who needs a Nemesis star with nomad planets like these zipping through the Oort Cloud?
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by orin stepanek » Sun Feb 26, 2012 1:33 pm

I don't know for sure; but I believe they would orbit around the galaxy the same as stars do! :?
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by neufer » Sun Feb 26, 2012 5:51 pm

orin stepanek wrote:
I don't know for sure; but I believe they would orbit around the galaxy the same as stars do! :?
Just like Ross 248 (HH Andromedae).

In 36,000 years Ross 248 will pass within 191,000 AU of the Sun.

Hence within about 36,000 years some 'Nomad Planet' might well pass within [(191,000/sqrt(100,000)=] 600 AU of the Sun.

That's a little close for comfort.
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Beyond » Sun Feb 26, 2012 7:12 pm

I don't remember what an AU is, so i feel rather comfortable. I've learned to use laziness to not look up such things. Makes life simpler in my :old: age. :mrgreen:
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by orin stepanek » Sun Feb 26, 2012 11:28 pm

Beyond wrote:I don't remember what an AU is, so i feel rather comfortable. I've learned to use laziness to not look up such things. Makes life simpler in my :old: age. :mrgreen:
AU is the distance between the Earth and the sun! http://en.wikipedia.org/wiki/Astronomical_unit
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Beyond » Mon Feb 27, 2012 12:29 am

Dagnabit orin, you almost made me be concerned about Ross 248, but seeing as how it wouldn't be a concern for about 36,000 years, i can put that off until later. :mrgreen:
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by orin stepanek » Mon Feb 27, 2012 3:07 am

I wouldn't worry about 191,000 AU either; That's almost 6000 times further than Pluto! :wink: Just goes to show that somethings can show up when least expected though! :mrgreen: http://en.wikipedia.org/wiki/Ross_248
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Doum » Mon Feb 27, 2012 6:07 pm

orin stepanek wrote:I wouldn't worry about 191,000 AU either; That's almost 6000 times further than Pluto! :wink: Just goes to show that somethings can show up when least expected though! :mrgreen: http://en.wikipedia.org/wiki/Ross_248
Neufer said 600 AU not 191,000 AU. And at 600 AU, the problem may be that a nomad planet divert Oort object orbit toward the sun and us. Then we will be bombard by a swarm of comets. That is not going to be nice. But hey why bother, we cant do a thing about it. Except scream. If it help? :mrgreen:

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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by orin stepanek » Mon Feb 27, 2012 8:37 pm

Doum wrote:
Neufer said 600 AU not 191,000 AU. And at 600 AU, the problem may be that a nomad planet divert Oort object orbit toward the sun and us. Then we will be bombard by a swarm of comets. That is not going to be nice. But hey why bother, we cant do a thing about it. Except scream. If it help? :mrgreen:
In 36,000 years Ross 248 will pass within 191,000 AU of the Sun.

Hence within about 36,000 years some 'Nomad Planet' might well pass within [(191,000/sqrt(100,000)=] 600 AU of the Sun.
I'm not sure why he is figuring [(191000/sqrt(100'000)=] 600 AU of the Sun; but even so. that's still almost 20 times further than Pluto and that's still pretty far! :wink: Anyway; in 36,000 years, I'll have to go along with Beyond and put it off 'til later! :|
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by neufer » Mon Feb 27, 2012 9:09 pm

orin stepanek wrote:
Doum wrote:
Neufer said 600 AU not 191,000 AU. And at 600 AU, the problem may be that a nomad planet divert Oort object orbit toward the sun and us. Then we will be bombard by a swarm of comets. That is not going to be nice. But hey why bother, we cant do a thing about it. Except scream. If it help? :mrgreen:
In 36,000 years Ross 248 will pass within 191,000 AU of the Sun.

Hence within about 36,000 years some 'Nomad Planet' might well pass within [(191,000/sqrt(100,000)=] 600 AU of the Sun.
I'm not sure why he is figuring [(191000/sqrt(100,000)=] 600 AU of the Sun; but even so. that's still almost 20 times further than Pluto and that's still pretty far! :wink: Anyway; in 36,000 years, I'll have to go along with Beyond and put it off 'til later! :|
It's actually more the idea that about every 15 million (= 400 x 36,000) years
a 'Nomad Planet' might shoot within about [600/sqrt(400) =] 30 AU of the Sun.

I find that a little disconcerting in so far as the future of the solar system is concerned.
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Doum » Mon Feb 27, 2012 9:45 pm

30 AU! OK, now that is very close to create a swarm of comets. Or a flock of comets or a gang of comets or... :shock: AHHHHHHHHHHHHHH, uhh nope . Screaming change nothing to that fact. :? At least i try. :mrgreen: Hmmm. what was the rate of extinction on earth already. I kind of forget.

Out of curiosity, can we detect a planet the size of earth at say 150 AU from earth?

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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Chris Peterson » Mon Feb 27, 2012 10:35 pm

neufer wrote:It's actually more the idea that about every 15 million (= 400 x 36,000) years
a 'Nomad Planet' might shoot within about [600/sqrt(400) =] 30 AU of the Sun.

I find that a little disconcerting in so far as the future of the solar system is concerned.
Why? If true- and if these passes actually produce some comet swarms (which there is weak evidence for)- it has happened hundreds of times in the history of the Solar System. It apparently hasn't led to any serious harm. Maybe a few minor to moderate extinction events, but so what? Those have only served to shake the biosphere up a bit.
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by orin stepanek » Mon Feb 27, 2012 11:37 pm

neufer wrote:
It's actually more the idea that about every 15 million (= 400 x 36,000) years
a 'Nomad Planet' might shoot within about [600/sqrt(400) =] 30 AU of the Sun.

I find that a little disconcerting in so far as the future of the solar system is concerned.
Ahh! Now we're getting approximately toward the distance of Pluto! But still; 36000 years? I'll be gone by then! :wink: :mrgreen: Have a :b: and relax! :)
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by neufer » Tue Feb 28, 2012 1:40 am

Doum wrote:
Out of curiosity, can we detect a planet the size of earth at say 150 AU from earth?
Probably at 200 AU from earth.

Trans-Neptunian object Eris has less than a fifth the diameter of the earth and it was discovered at 97 AU from earth. :arrow:
http://en.wikipedia.org/wiki/Eris_%28dwarf_planet%29 wrote:
<<Eris, formal designation 136199 Eris, is the most massive known dwarf planet in the Solar System and the ninth most massive body known to orbit the Sun directly. It is estimated to be approximately 2300–2400 km in diameter, and 27% more massive than Pluto or about 0.27% of the Earth's mass. Eris was discovered in January 2005 by a Palomar Observatory-based team led by Mike Brown, and its identity was verified later that year. It is a trans-Neptunian object (TNO) and a member of a high-eccentricity population known as the scattered disc. It has one known moon, Dysnomia. As of 2011, its distance from the Sun is 96.6 AU.>>
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Chris Peterson » Tue Feb 28, 2012 1:53 am

Doum wrote:Out of curiosity, can we detect a planet the size of earth at say 150 AU from earth?
That would depend on its albedo. Earth is mostly covered with water, which would be ice at 150 AU. Assuming some other process hadn't darkened the surface, its albedo would be similar to some of the TNOs, and given its comparatively large size, would certainly be detectable with large ground-based telescopes.
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Doum » Wed Feb 29, 2012 6:17 pm

Thanks Chris.

So, if we have done the 3 dimensions survey around the solar system at 200 AU distance then no nomad planet have been detected so far. Thats great. Now, even if we detect a nomad planet at say 30 hour light year distance or 200 AU distance (estimate here i may be wrong) then we will have a few centurys or millenia to react for what is coming because 30 hour light year is a very long distance to travel.(our reaction can be expanding humankind to colonise many world in the solar system wich will increase the chance for humankind to survive in the coming comet swarms??) Or a nomad planet have already pass near the solar system and something is on his way near you. :(

Time will tell!

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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Chris Peterson » Wed Feb 29, 2012 6:42 pm

Doum wrote:Now, even if we detect a nomad planet at say 30 hour light year distance or 200 AU distance (estimate here i may be wrong) then we will have a few centurys or millenia to react for what is coming because 30 hour light year is a very long distance to travel.(our reaction can be expanding humankind to colonise many world in the solar system wich will increase the chance for humankind to survive in the coming comet swarms??)
This assumes that a planet passing through the Oort cloud would produce a significant number of comets moving into the inner system. Personally, I think it unlikely. The density of bodies in the Oort cloud is low, and a planet isn't very massive. We're not talking about a star passing nearby. And even if the rate of comets increases for a few thousand years, that doesn't spell doom for the Earth, or even for humans. A collision with Earth remains unlikely.
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by neufer » Wed Feb 29, 2012 7:37 pm

PLANET, n. [L. planeta; from Greek πλανήτης αστήρ planētēs astēr "wandering star" wandering, to wander.]
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NOMAD, n. [L. nomas, -adis, roaming without fixed home, from Greek: νομάδες, nomádes, "those who let pasture herds": This verb is connected with L. Nemus, a wood :tree: , a place over-grown with trees, and also a pasture, the primary sense of which is probably to spring or shoot, for the verb signifies among other things, to leap, to dance, and may be allied to Eng. nimble. Cf. Astronomy, Economy, Nimble, Nemesis, Numb, Number.] One who leads a wandering life, and subsists by tending herds of cattle which graze on herbage of spontaneous growth. The Numidians in Africa are supposed to have been so called from this practice.
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by orin stepanek » Wed Feb 29, 2012 8:38 pm

:idea: Nomad Planet=wandering wanderer? :?: :shock: :roll: 8-) :mrgreen:
Click to play embedded YouTube video.
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Beyond » Wed Feb 29, 2012 10:52 pm

Hey orin, Great video :!: :yes: :thumb_up: :clap: Are all those critters your pets :?:
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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by Ann » Thu Mar 01, 2012 1:34 am

Have you made that video, Orin?

Well, whether it was or not, it was a nice video, full of "wandering" animals! :D I think I remember that you have a dog, whose name may possibly be Sasha. That black dog looks a little like Sasha in a picture you showed us some time ago.

I think my favorite picture may be the mouse sitting inside what looked like a huge green ring with a stone. I though for a moment that Lex Luthor had put a mouse in the kryptonite stone of his anti-Superman ring! :mrgreen: But I think that the mouse was just sitting inside a green watering can!

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Re: Stanford: Galaxy May Swarm with 'Nomad Planets'

Post by orin stepanek » Thu Mar 01, 2012 9:39 pm

Ann wrote:Have you made that video, Orin? :D I think I remember that you have a dog, whose name may possibly be Sasha.

Ann
No I didn't make the video! I found it on youtube with my search engine and I thought it fit the nomads! My dog's name is Sassy; so you got close on that one! :wink: I don't have any other animals even though the squirrels and rabbits run rampant in the neighborhood! :mrgreen:
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Kavli: Nomads of the Galaxy

Post by bystander » Wed May 23, 2012 7:26 pm

Nomads of the Galaxy
Kavli Foundation | Science Spotlights | 2012 May 23
Image
Planets simply adrift in space may not only be common in the cosmos; in the Milky Way Galaxy alone, their number may be in the quadrillions. Three experts discussed what this might mean, whether a nomad planet could drift close to our solar system, and how it is possible for a nomad planet to sustain life.
Image
An artistic rendition of a nomad object wandering the interstellar medium.
The object is intentionally blurry to represent uncertainty about whether or
not it has an atmosphere. A nomadic object may be an icy body akin to an
object found in the outer Solar System, a more rocky material akin to
asteroid, or even a gas giant similar in composition to the most massive
Solar System planets and exoplanets. (Image by Greg Stewart/SLAC)

The Kavli Foundation spoke recently with two of the authors of the new nomad planets study, as well a leading researcher in the search for planets and life beyond Earth. The participants:

Worlds Without Suns: Nomad Planets Could Number In The Quadrillions
Universe Today | Jason Major | 2012 May 30

See also: http://asterisk.apod.com/viewtopic.php?t=28300
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