Cancer Posted August 4, 2006 Report Share Posted August 4, 2006 I saw a garbled item this morning in my morning paper (this) and finally tracked down the ESO press release. The newspaper item mentions a paper in Science but I didn't find it there. A pair of planetary-mass objects has been found, in a mutual orbit, but not in orbit around a stellar-mass object. The planets are big ones, 7 and 14 Jupiter masses, but still definitely in the planetary-mass regime. AFAIK, this is the first claimed detection for "free" (that is, starless) planets. It's worth noting that for older "free" planets, detection is wellnigh impossible: they don't radiate appreciably, so there's nothing to observe. However, newly-formed objects, including these Jupiter-class planets, are warm enough that a cutting-edge telescope and infrared camera can detect them before they cool to unobservability. That is what has happened here: these things are in a known star-formation region, young and warm enough to be seen, but small and faint enough that they must be planets. I've seen suggestions in the technical literature before that planets were unlikely to be formed by themselves, and how those suggestions fare with this discovery isn't clear to me. Statistics are very hard to do from only one case. It still could be that this a freak instance; that's impossible to judge at this point. So there's no telling (yet) how many free planets there are floating aroudn in the Galaxy. There are processes known that would eject planets from a star system. There are likely to be a number of such "lost" planets floating free in the Galaxy, more or less impossible to find. This is the first case I've seen that clearly indicates that isolated planets also result from star formation. So, Star Hero universe builders, you have an existance theorem. You are now allowed to include "free planets" in your game universes. These Jupiter-class planets wouldn't be useable as bases by themselves, but there's no reason they wouldn't have moons, and the planets themselves would be adequate sources for light elements (hydrogen, carbon, nitrogen, oxygen compounds, and deuterium, if that's your fusion energy source of choice). They'd be dark and cold, but almost impossible to find by conventional astronomical means. (Secret base, anyone?) Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted August 4, 2006 Report Share Posted August 4, 2006 Re: Planets not orbiting stars Space Pirates! Tortuga Base! Tortuga means "turtle." Turtle in space. Great A'tuin? . . . Lack of sleep noticeable . . . cbullard 1 Quote Link to comment Share on other sites More sharing options...
gamerz123 Posted August 4, 2006 Report Share Posted August 4, 2006 Re: Planets not orbiting stars Talk about Interstellar potholes..... "Sorry, Admiral.... We lost 3 ships on the way to the frontier battle because of a rogue planet." "Dagnabit! That's the third time this month!" Quote Link to comment Share on other sites More sharing options...
Old Man Posted August 4, 2006 Report Share Posted August 4, 2006 Re: Planets not orbiting stars A black hole backed up like a toilet? A star collapsed but didn't go nova? Dahak lost his stealth ability? Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted August 5, 2006 Report Share Posted August 5, 2006 Re: Planets not orbiting stars . . . Where's Dark Star when you need her?! Quote Link to comment Share on other sites More sharing options...
Curufea Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars I'd always presumed that rogue planets came from systems that went supernova. Like any other object in space, large gravity fields could capture them. The problem being the very, very low probability of them wandering into said gravity fields. Quote Link to comment Share on other sites More sharing options...
TheRavenIs Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars That old movie When Worlds Collide looks more and more possiable. Now how do I make that happen in a game I run? Quote Link to comment Share on other sites More sharing options...
Lord Liaden Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars Given the conditions described for the area where these planets were detected, I'm wondering if they couldn't have resulted from the same processes that create stars, but simply didn't collect enough mass to reach the pressure and temperature needed to achieve fusion. Quote Link to comment Share on other sites More sharing options...
Lord Liaden Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars That old movie When Worlds Collide looks more and more possiable. Now how do I make that happen in a game I run? What kind of game are you running/planning to run, and what do you want to have happen? Quote Link to comment Share on other sites More sharing options...
TheRavenIs Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars What kind of game are you running/planning to run' date=' and what do you want to have happen?[/quote'] If I can get the War Of the World book, I'll be doing alot of the old B-Movies. Actually a Dark Champion with a Plup feel with a dash of Star Hero. Quote Link to comment Share on other sites More sharing options...
austenandrews Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars That old movie When Worlds Collide looks more and more possiable. Now how do I make that happen in a game I run? You know they're remaking it, right? Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars Whee! A modern B-movie! I love those! Quote Link to comment Share on other sites More sharing options...
Dale A. Ward Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars Given the conditions described for the area where these planets were detected' date=' I'm wondering if they couldn't have resulted from the same processes that create stars, but simply didn't collect enough mass to reach the pressure and temperature needed to achieve fusion.[/quote'] Well, as I understand it, they're basicly orbiting each other... correct? So, maybe, if they were to eventually come in contact with each other and combine, they WOULD have the required mass and temperature. ~SCRUNCH~ New star! Quote Link to comment Share on other sites More sharing options...
Dr. Anomaly Posted August 6, 2006 Report Share Posted August 6, 2006 Re: Planets not orbiting stars Well, as I understand it, they're basicly orbiting each other... correct? So, maybe, if they were to eventually come in contact with each other and combine, they WOULD have the required mass and temperature. ~SCRUNCH~ New star! Mmm... I doubt it. The figures I've seen as the minimum mass necessary for stellar ignition range from 5% to 8% of our sun's mass, and Jupiter has .1% of our sun's mass. These two objects together would equal 21 times Jupiter's mass, or 2.1% of a solar mass, which is below the most generous figures I've seen by a bit better than a factor of 2. (The minimum mass necessary for stellar ignition is something I've seen hotly debated, and the arguments include variables such as the exact make-up of the material of the newly-formed object, how much deuterium is in the mix, various other "contaminant heavy elements" [anything heavier than lithium] and so on. Cancer probably has more exact, or at least more recent, figures than I do.) Quote Link to comment Share on other sites More sharing options...
Curufea Posted August 7, 2006 Report Share Posted August 7, 2006 Re: Planets not orbiting stars One of the theories on solar system creation is accretion. I'm not sure if there are others. Dust and gasses attracted to each other by their miniscule gravity, ending up all spining in the same plane and direction - hence orbits and planetary rotations. The core has the largest mass, but a few pockets here and there of large clumps that become the planets. Quote Link to comment Share on other sites More sharing options...
Cancer Posted August 7, 2006 Author Report Share Posted August 7, 2006 Re: Planets not orbiting stars Given the conditions described for the area where these planets were detected' date=' I'm wondering if they couldn't have resulted from the same processes that create stars, but simply didn't collect enough mass to reach the pressure and temperature needed to achieve fusion.[/quote'] That would be my initial guess, but it's also possible that they formed in a multiple star system and were ejected very early on. If this system is unique, that argues for the ejection hypothesis, since the circumstances that eject a pair of jovian planets in mutual orbit are going to be ... special. On the other hand, if it turns out this is the first set discovered of a large population, then it seems likely that the low-mass "tail" of the star formation mass distribution extends to lower masses than has been commonly thought. The figures I've seen as the minimum mass necessary for stellar ignition range from 5% to 8% of our sun's mass, and Jupiter has .1% of our sun's mass. These two objects together would equal 21 times Jupiter's mass, or 2.1% of a solar mass, which is below the most generous figures I've seen by a bit better than a factor of 2. (The minimum mass necessary for stellar ignition is something I've seen hotly debated, and the arguments include variables such as the exact make-up of the material of the newly-formed object, how much deuterium is in the mix, various other "contaminant heavy elements" [anything heavier than lithium] and so on. Cancer probably has more exact, or at least more recent, figures than I do.) I'm not sure I've seen anything other than 0.08 solar masses for that number, at least for near-solar composition. For near-zero-metals stars, that is, the first generation, that's a more difficult and controversial question. For reference, 1 jupiter mass ~ 1/1000 solar mass, so you need 80 to 85 jupiter masses to get to the threshhold of standard hydrogen-fusing stars. Things somewhat less massive than this will fuse deuterium (which is much easier than hydrogen) for a while, but once they run out (which will happen quickly, since D/H ~ 10^-5) they cool off to becoming super-Jupiters. Quote Link to comment Share on other sites More sharing options...
Lord Liaden Posted August 7, 2006 Report Share Posted August 7, 2006 Re: Planets not orbiting stars Mmm... I doubt it. The figures I've seen as the minimum mass necessary for stellar ignition range from 5% to 8% of our sun's mass, and Jupiter has .1% of our sun's mass. These two objects together would equal 21 times Jupiter's mass, or 2.1% of a solar mass, which is below the most generous figures I've seen by a bit better than a factor of 2. (The minimum mass necessary for stellar ignition is something I've seen hotly debated, and the arguments include variables such as the exact make-up of the material of the newly-formed object, how much deuterium is in the mix, various other "contaminant heavy elements" [anything heavier than lithium] and so on. Cancer probably has more exact, or at least more recent, figures than I do.) Well, if anyone spots any monoliths near these things, they'd better steer clear. Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted August 7, 2006 Report Share Posted August 7, 2006 Re: Planets not orbiting stars . . . I wanna see stars. Don't you? Quote Link to comment Share on other sites More sharing options...
austenandrews Posted August 8, 2006 Report Share Posted August 8, 2006 Re: Planets not orbiting stars I wonder what it would take to snag one of those puppies and put it into orbit around one's home star. Quote Link to comment Share on other sites More sharing options...
Basil Posted August 10, 2006 Report Share Posted August 10, 2006 Re: Planets not orbiting stars That would be my initial guess' date=' but it's also possible that they formed in a multiple star system and were ejected very early on. If this system is unique, that argues for the ejection hypothesis, since the circumstances that eject a pair of jovian planets in mutual orbit are going to be ... special. On the other hand, if it turns out this is the first set discovered of a large population, then it seems likely that the low-mass "tail" of the star formation mass distribution extends to lower masses than has been commonly thought.[/quote'] From the article: it is likely that these planemo twins formed together out of a contracting gas cloud that fragmented, like a miniature stellar binary," said Jayawardhana....[their] existence poses a challenge to a popular theoretical scenario, which suggests that brown dwarfs and free-floating planetary mass objects are embryos ejected from multiple proto-star systems. Since the two objects in Oph1622 are so far apart, and only weakly bound to each other by gravity, they would not have survived such a chaotic birth. So, they definitely think this pair of planets were formed separately from any star. I'm not sure I've seen anything other than 0.08 solar masses for that number, at least for near-solar composition. For near-zero-metals stars, that is, the first generation, that's a more difficult and controversial question. For reference, 1 jupiter mass ~ 1/1000 solar mass, so you need 80 to 85 jupiter masses to get to the threshhold of standard hydrogen-fusing stars. Things somewhat less massive than this will fuse deuterium (which is much easier than hydrogen) for a while, but once they run out (which will happen quickly, since D/H ~ 10^-5) they cool off to becoming super-Jupiters. The article covers this, saying: brown dwarfs, 'failed stars' that have less than 75 Jupiter masses and are unable to sustain nuclear fusion in their cores. They use a figure of 75 J-masses, which is close enough to your figure of 80-85. BTW, please note this quote from the article: During the past five years, astronomers have identified a few dozen of even smaller free-floating planetary mass objects, or planemos, in nearby star forming regions. So, planet-sized objects are rather common. Frankly, I don't see how one could assume they are all (or mostly) "lost" planets. For that to be true, star systems would have to be intrincsically unstable. Quote Link to comment Share on other sites More sharing options...
Cancer Posted August 10, 2006 Author Report Share Posted August 10, 2006 Re: Planets not orbiting stars Frankly' date=' I don't see how one could assume they are all (or mostly) "lost" planets. For that to be true, star systems would have to be intrincsically unstable.[/quote'] Actually, over long timescales, most multiplanet systems are dynamically unstable, and they evolve appreciably. Sometimes they find resonant conditions that persist for multiple Gyr (like ours). Sometimes things get ejected or accreted quickly. I'm not saying their conclusion is wrong. I'm just not convinced yet and need to see more evidence. It is quite interesting. Quote Link to comment Share on other sites More sharing options...
Old Man Posted August 11, 2006 Report Share Posted August 11, 2006 Re: Planets not orbiting stars The telling thing for me is that the planemawhatsits are orbiting each other. That's highly unlikely in an ejection scenario. Quote Link to comment Share on other sites More sharing options...
Yansuf Posted August 11, 2006 Report Share Posted August 11, 2006 Re: Planets not orbiting stars That old movie When Worlds Collide looks more and more possiable. Now how do I make that happen in a game I run? The original book (from the early 1930's) is much better than the movie. There was also a sequel "After Worlds Collide." Quote Link to comment Share on other sites More sharing options...
Cancer Posted August 11, 2006 Author Report Share Posted August 11, 2006 Re: Planets not orbiting stars The telling thing for me is that the planemawhatsits are orbiting each other. That's highly unlikely in an ejection scenario. If they are in orbit, you're right. And, well, they are close to one another ... 2 arcseconds, a minimum of 240 AU at the distance of the cloud ... but there's no direct evidence of orbital motion at this point. And that will be a very long time coming, even if they are in such an orbit. If you assume a separation of 240 AU and a total of about 30 Jupiter masses in the system, their mutual orbital period is going to be on the order of tens of thousands of years. I think it'll take a systematic survey to resolve the question, looking for more of these things and then getting a decent number for how many there are. Quote Link to comment Share on other sites More sharing options...
TheRavenIs Posted August 13, 2006 Report Share Posted August 13, 2006 Re: Planets not orbiting stars The original book (from the early 1930's) is much better than the movie. There was also a sequel "After Worlds Collide." I never saw the sequel, always wanted to. I just like the idea of having a rouge planet or two enter the solar syatem just to play havok with the PC's, let alone the game world. I don't see this happening to the solar system in the game I am running in, but it might in another one. Quote Link to comment Share on other sites More sharing options...
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