Planets that have no stars: New class of planets discovered
This artist's conception illustrates a Jupiter-like planet alone in the dark of space, floating freely without a parent star. Astronomers recently uncovered evidence for 10 such lone worlds, thought to have been "booted," or ejected, from developing solar systems. Image credit: NASA/JPL-Caltech
(PhysOrg.com) -- University of Notre Dame astronomer David Bennett is co-author of a new paper describing the discovery of a new class of planets -- dark, isolated Jupiter-mass bodies floating alone in space, far from any host star. Bennett and the team of astronomers involved in the discovery believe that the planets were most likely ejected from developing planetary systems.
The study is described in a paper appearing in the May 19th issue of the journal Nature.
The discovery stems from an analysis of observations of the central bulge of the Milky Way galaxy taken in 2006 and 2007 by a joint Japan-New Zealand survey. This analysis provides evidence of what appear to be 10 free-floating planets roughly the mass of Jupiter. Bennett explains the likely origin of these isolated planets, "Our results suggest that planetary systems often become unstable, with planets being kicked out from their places of birth by close encounters with other planets".
This discovery not only confirms that free-floating planets exist in space, but also indicates that they are quite common. Free-floating planets are very hard to detect, so the fact that the survey found up to 10 implies that there are many more that are not detected. The team of scientists that made the discovery estimates that there are about twice as many free-floating Jupiter-mass planets as stars. This implies that free-floating planets are likely to be least as common as planets, like ours, that orbit stars.
"Our survey is like a population census — we sampled a portion of the galaxy and, based on these data, can estimate overall numbers in the galaxy," Bennett said. "The survey is not sensitive to planets less massive than Jupiter and Saturn, but theories suggest that lower-mass planets like Earth should be ejected from their stars more often and are thus more common that free-floating Jupiters." Some scientists have even suggested that free-floating Earth-mass planets could be warm enough to host life, due to the greenhouse effect of a large amount of Hydrogen in their atmospheres. NASA's planned WFIRST mission will use the microlensing method to reveal how many free-floating Earth-mass planets inhabit the Milky Way galaxy.
The survey that revealed the planets is called the Microlensing Observations in Astrophysics (MOA). A 1.8-meter (5.9-foot) telescope at Mt. John University Observatory in New Zealand is used to regularly scan the stars at the center of the Milky Way galaxy for what are referred to as "gravitational microlensing events."
Bennett is a pioneer in the gravitational microlensing method, which takes advantage of the fact that light is bent as the rays pass close to a massive object, like a star. The gravity from the mass of the foreground planet warps surrounding space and acts like a giant magnifying glass. As predicted by Albert Einstein and later confirmed, this phenomena causes an apparent brightening of the light from a background "source" star. The effect is seen only if the astronomer's telescope lies in almost perfect alignment with the source star and the lens star. The primary challenge of the microlensing method is the precise alignments needed for the planetary microlensing signals are quite rare and brief, lasting less than two days.
Astronomers are also able to detect planets orbiting stars if the light from the background star is warped by both the planet and its host star.
Bennett and the team of scientists found about 10 short microlensing events, indicating planets of roughly Jupiter's mass. The team said that it can't rule out the possibility that some of the planets may be in very distant orbits about stars, but previous observations by other groups suggests that Jupiter-mass planets in such distant orbits are rare. Future observations by the Hubble Space Telescope should detect many of these host stars, if they exist.
"If free-floating planets formed like stars, then we would have expected to see only one or two of them in our survey instead of 10," Bennett said.
Provided by
University of Notre Dame
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May 18, 2011
Rank: 2.5 / 5 (2)
May 18, 2011
Rank: 1.6 / 5 (17)
However, this study and article are ridiculous. The idea of rogue planets has already been proposed, and I suspect that the evidence provided by this astronomer has not been confirmed by anyone else.
May 18, 2011
Rank: 5 / 5 (11)
Yeah, articles published in "Nature" are trash, no peer-review or anything right?
May 18, 2011
Rank: 5 / 5 (7)
What's ridiculous about it? I really don't understand why you're bashing it.
May 18, 2011
Rank: 5 / 5 (7)
May 18, 2011
Rank: 3.4 / 5 (7)
Admitting that I know nothing - if there are a large number of these plants, how much of dark matter would it explain?
May 18, 2011
Rank: 1.2 / 5 (5)
Nature may be peer reviewed, and I do not doubt that the research has been done properly, but I seriously doubt the evidence is firm enough to qualify as a discovery yet by any stretch of imagination.
May 18, 2011
Rank: not rated yet
May 18, 2011
Rank: 4.8 / 5 (6)
Someone correct me if I'm wrong, but I think bodies like this are already accounted for in the known mass. Dark matter is some entirely other thing like some kind of subatomic or quasi-particle that has a mass we are unaware of, or maybe something else we haven't even theorized yet.
The idea of a planetary mass object on a ballistic path through open space is actually a little frightening. It wouldn't even need to hit Earth. An impact with any planet or moon in the solar system would kick up enough debris to cause us much grief. Even a near miss might be rather bad luck.
May 18, 2011
Rank: 5 / 5 (6)
That said, There is an order of magnitude difference between matter/energy and dark matter/dark energy estimates, so astronomers are still fairly confident that if the estimates are changed, that it won't change anything fundamental, or only a minor push of the needle.
it would take an einstein level realization to change the current accepted outlook on mass ration/dark matter, etc.
May 18, 2011
Rank: 1.5 / 5 (2)
One would expect that once any object obtains enough mass to get over the "curve" so that it would not evaporate due to stellar winds, then it should exist in orbit around a star until it is either ejected or collides with something.
In order to have conservation of angular momentum in a system of orbiting bodies, some objects will be ejected from planetary systems and solar systems due to tidal forces or random constructive or destructive interference of gravitation during close encounters. At least, if you assume random initial distributions, masses, and velocities of objects inside the system, then some objects MUST be ejected before the system will become "relatively stable" over decent periods of time.
One would expect that the ratio of rogue planets and rogue planetesmals of any given mass should be, on average, proportional to the ratios in an average solar system.
May 18, 2011
Rank: 4.5 / 5 (8)
Yes, but we don't know what an average solar system looks like yet.
You know, taking that concept in reverse; If you could get a good survey of the sizes of rogue planets then it should tell you what an average solar system DOES look like.
May 18, 2011
Rank: 5 / 5 (12)
Wouldn't even need to be a near miss. A Jupiter sized object passing anywhere through the solar system would give us a good chance of being the next rogue planet!
May 18, 2011
Rank: 5 / 5 (1)
It also demonstrates a fallacy in the standard model of our own solar system, seeing as how there is no good reason to assume that every object in the Solar System was created within the solar system.
Some of the planets, moons and other objects could have been created some place else and moved here later.
After all, if a planet can capture a moon, then what's to stop a star from capturing a rogue planet or moon as a planet of it's own? Or what's to stop one planet from capturing another rogue planet as a moon of it's own?
If you had sufficient life support technology and happened to live in a solar system where you expected a planet will be ejected along a favourable path, it might be a "free" means of inter-stellar transportation and colonization, well, with ridiculously low probability anyway.
May 18, 2011
Rank: 5 / 5 (5)
May 18, 2011
Rank: 5 / 5 (5)
We should expect to find everything from the size of a grain of sand up to this monster
http://en.wikiped..._Majoris
and everything in between in space.
If one considers brown dwarfs it's not a stretch to assume even smaller bodies.
May 18, 2011
Rank: 3.7 / 5 (6)
Pluto is not a rogue planet, nor are any of the known dwarf planets or large comets in the outer solar system, yet they have mean temperatures hundreds of degrees below the freezing point of carbon dioxide, and even below the vapor point of nitrogen.
Even if you started with a gas giant it would freeze out into a ball of dry ice, water-ice, methane-ice within a relatively short time period.
There is no such thing as an ideal greenhouse gas, and even if there were such a thing, no planet would be composed of 100% of that gas.
So even a gas giant would radiate away it's heat in short order and then freeze out into a ball of ice. End of story, end of any life, certainly.
May 18, 2011
Rank: 1.8 / 5 (5)
May 18, 2011
Rank: 5 / 5 (4)
Also, gas giants generate far more heat than Earth class planets and for far longer. (Not that this makes them necessarily any more habitable ;^)
May 18, 2011
Rank: 5 / 5 (1)
Why is it a fallacy? We have a "standard" model because it works with observed evidence. If there comes a time when Rogue planets being captured by Solar Systems is observed to be commonplace then the "standard" model will be revised. Do you have evidence to support the opinion that our Solar System was mainly populated by Rogues?
Hint: "STANDARD" model is called that for a reason.
May 18, 2011
Rank: 2.5 / 5 (2)
There are even plenty of inter-galactic solar systems.
I recommend "Beyond the Moon", a great book on astronomy by one of Italy's, and this world's, greatest former contemporary astronomers. May he rest in peace.
May 18, 2011
Rank: 3.7 / 5 (3)
In the alleged big bang model, heavy atoms do not exist until the deaths of the first generation stars, which means that in the big bang model, it would be impossible for a planet sized object, other than a hydrogen gas giant, to ever form until after the deaths of the first generation stars.
May 18, 2011
Rank: not rated yet
Furthermore, the orbital mechanics of a many-body system in the long term is always unstable, hence these rogue planets are to be expected.
May 18, 2011
Rank: 1.3 / 5 (10)
That is a major discovery!
Congratulations.
It is true that giant, gaseous, Jupiter-like planets probably form far from the star that ejects the material, just as Jupiter, Saturn, Uranus and Neptune did at the birth of the solar system:
www.omatumr.com/Origin.htm
Here is a recent review of the experimental data that led to this conclusion about the birth of the solar system ["Neutron Repulsion", The APEIRON Journal, in press, 19 pages (2011)]
http://arxiv.org/...2.1499v1
Planets that have no stars would be a major discovery.
With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
May 18, 2011
Rank: not rated yet
There is no reason to assume that most of those small bodies orbit larger stars.
May 18, 2011
Rank: 5 / 5 (6)
Nothing stops a star from capturing other objects in its well. However, the chances of those objects all orbiting the same direction in the same ecliptic, and all mass/element distributed in the orbits that they should be in if they formed from the primary's accretion disc rather than captured at random defies calculation.
The only object that seems out of place as far as planets go is Pluto. All of the other eight planets are right where they would be if they formed here in the original disc, all in the same plane. Occam's razor, dude.
May 18, 2011
Rank: 5 / 5 (1)
That's not true at all.
A large number of known comets and planetesmals in our solar system orbit on planes significantly different from the ecliptic.
Sedna, Pluto, Eris,a nd Pallas have inclinations of 11, 17, 44, and 34 degrees respectively, and these are are relatively large, "Borderline planet" objects.
In fact, under the old definition of a planet, all of them would be considered "planets". Those are just some big ones I found right away. That doesn't count all of the countless comets and asteroids on inclined orbits.
You are mis-applying Occam's Razor to say something it does not say.
You are implying that "because something may appear simple it must have a simple explaination". That is clearly a fallacy.
May 18, 2011
Rank: 3 / 5 (2)
May 18, 2011
Rank: not rated yet
Not necessarily.
In some cases, they could end up on a hyperbolic trajectory which has obtained galactic escape velocity via gravity assist in the same manner as space probes such as Voyager 1 and 2, although the space probes don't have galactic escape velocity, they merely exceed solar escape velocity.
While this is extremely unlikely in most cases for planets, it is theoretically possible if the right close encounter ocurred with a massive enough body which has enough spin to transfer angular momentum to the rogue planet.
Such extremely rare rogue objects, if they exist, may be traveling "through" the galaxy until they exit at and edge and continue escaping on a hyperbolic trajectory.
May 18, 2011
Rank: 5 / 5 (1)
May 18, 2011
Rank: not rated yet
(Hosting low-density planets larger in 'size' than their high-density hostess star?)
Is this nonsense?
Hard to tell how far OT(off-topic) this is, when considering stellar/planetary scenarios.
May 18, 2011
Rank: not rated yet
There is at least one known circum-binary Pulsar Planet, unofficially, yet appropriately called "Methuselah".
wikipedia.org/wiki/Methuselah_(planet)
It orbits both a white dwarf and a pulsar, and is apparently in a stable orbit.
The planet is probably a second generation planet, and probably formed (or was captured) after the supernova created the Pulsar, seeing as how the supernova and/or it's synchrotron radiation should have destroyed at the molecular level and ionized the planet, ejecting it as a cloud of ions and dust, had it been there during the supernova or immediately afterwards.
This is a 3 body system with 2 very massive stars: a candidate for hyperbolic galactic escape velocity ejection over long time scales.
May 18, 2011
Rank: not rated yet
May 18, 2011
Rank: not rated yet
May 18, 2011
Rank: 1.7 / 5 (3)
May 19, 2011
Rank: 1 / 5 (1)
May 19, 2011
Rank: not rated yet
Lol.
Anyway on the topic at hand this is a fascinating find in my opinion and it akes you wonder what else is out there in the dark depths of space?
May 19, 2011
Rank: 5 / 5 (1)
May 19, 2011
Rank: not rated yet
May 19, 2011
Rank: 5 / 5 (1)
I was referring to the planets, not the comets, snowballs, Kuiper objects. You said some of the planets (of which there are 8) could have been captured. Occam's Razor DOES dictate that if you see a planet orbiting in the ecliptic in its appropriate mass/element distribution ring, it's FAR more likely that it formed out of the accretion disc rather than it being a rogue planet that formed elsewhere that just happened to get inserted into its appropriate slot. I didn't misapply it all.
Note also that the article refers to Jupiter class masses, not rogue comets.
May 19, 2011
Rank: 1 / 5 (4)
There are stars like Barnard's Star that are "runaway stars" but none of a Jupiter size. Planets belong to their parent Sun just as moons belong to their parent Planet. Without the gravitational pull of a Sun, a planet cannot just "wander" BECAUSE it has no mechanism to rotate aimlessly.
The Jupiters of the article will be found to have a parent.
Dwyer article 2008
May 19, 2011
Rank: not rated yet
these planets remind me of how like 80% of the planets they landed on did not have a star that was close.
May 19, 2011
Rank: 5 / 5 (1)
Why would a rogue planet or any other non-luminous object have different orbital rules than a star?
If a star can orbit nothing at all, or orbit only the galactic CoG, then why can't a rogue planet?
May 19, 2011
Rank: not rated yet
May 19, 2011
Rank: not rated yet
I don't know, I kind of agree with the need for a new definition. It came down to rewriting the textbooks once more, or thousands of times as new Kuiper belt objects are discovered. If Pluto was in, they all get in.
This way, there's 8 major planets, there will always be 8 major planets; one rewrite versus potentially thousands.
May 19, 2011
Rank: 5 / 5 (3)
Why not call them planemos? (aka planetary mass objects): http://en.wikiped..._objects
This term has been around for some time and refers to both rogue planets that have been ejected from their parent solar system and sub-brown dwarfs (that formed through cloud collapse independent of a star).
_____________________________
Also, not directly mentioned in this article, several *candidate* planemos have been directly detected in several nearby star-forming regions. The Nature paper discussed here has references to several such instances: http://arxiv.org/...44v1.pdf
Two recent papers:
http://arxiv.org/...06v1.pdf
http://arxiv.org/...25v1.pdf
May 19, 2011
Rank: not rated yet
I thought earth-sized planets couldn't hold onto hydrogen in any appreciable amount? Anyway, doesn't seem like it'd be to fruitful looking at these things to harbor life considering how hard it is to even find a likely solar system...
I suppose they'd be easier to detect than smaller ateroids / comets and easier to predict their path once discovered, but harder to do anything about? Also, there may be lots of orphan planets but wouldn't they also have shorter "life-spans" without a solar system or galaxy around them like we have to absord the very kinds of threats they present? Would most of these things end up destroyed (or absorbed) by other galactic debris?
May 21, 2011
Rank: not rated yet
The possibility arises that such planets may occasionally carry enough internal heat to sustain or originate life.
May 22, 2011
Rank: 1 / 5 (3)
I was thinking the same thing. As the reality of Cold Fusion permiates the collective conciousness it will become less certain that the interior of failed suns are frigid.
May 23, 2011
Rank: not rated yet
Also, correct me if I am wrong, but isn't a planet's rotational movement unrelated to being in orbit around a sun? But I cannot recall what makes the earth rotate... sorry!
May 23, 2011
Rank: 5 / 5 (1)
All planets rotate, just as all stars and their accretion discs rotate, since it is highly unlikely that any cloud of gas and dust would have zero angular momentum.
The possiblility of such a planet having moderate temperatures due to a thick atmosphere is not the same as making it suitable for life. Thermal energy cannot be converted to other energy without a local temperature gradient. Even if the surfaces are at room temperature the pitch dark surface will not support photosynthesis. Some chemical energy may be available as a result of geothermal chemistry or irradiation of molecules by the slowly decaying radioisotopes in the crust.
May 23, 2011
Rank: 1 / 5 (1)