Interstellar plant?

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Interstellar plant?

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1guido47
Jan 8, 2013, 5:20am

Dear Group,

For some unknown reason, this report, sends shivers...

Too much SF I imagine.

Link

2Mr.Durick
Jan 8, 2013, 4:45pm

This article is not the one I was looking for, but reflects interestingly on both interstellar plants and interstellar planets. The article I was looking for said, I think, that there are an estimated quadrillion interstellar planets in our galaxy.

Robert

3timspalding
Modifié : Jan 8, 2013, 5:11pm

How many of them are powered

4lorax
Jan 8, 2013, 7:33pm

What the hell is an "interstellar planet"? At any rate, "quadrillion" (10^15) is ridiculously high for "free-floating planets", i.e. planets that aren't associated with a star, and even for just "planets". Maybe if they're counting asteroids.

5Mr.Durick
Jan 8, 2013, 7:47pm

This Wikipedia article says that there may be [my emphasis] up to 100,000 more interstellar planets than there are stars in the Milky Way.

Robert

6lorax
Modifié : Jan 8, 2013, 7:57pm

1. 100,000 + 100 billion != 1 quadrillion. (That's your error, though, not wikipedia's, which along with the press release says "100,000 times").

2. "Interstellar planet" is not a term that I have ever heard any reputable astronomer use. "Free-floating planet" is the standard terminology.

3. Those guys aren't astronomers. They're no more experts on the subject than you are. They're doing ridiculous extrapolation and have no plausible formation mechanism.

Oh, and

4. Wikipedia is not a source for this sort of thing.

7timspalding
Jan 8, 2013, 8:03pm

"Interstellar planet" is not a term that I have ever heard any reputable astronomer use. "Free-floating planet" is the standard terminology.

Really? We're going to bite someone's head off for that? ( And, er, don't look now, but it's in Oxford University Press' Astronomy Encyclopedia http://books.google.com/books?id=4mzvAAAAMAAJ&q=%22interstellar+planet%22&am... )

Does anyone know how fast the earth would cool if we were ejected? How soon would we be in "A Pail Full of Air" situation?

8lorax
Modifié : Jan 8, 2013, 8:18pm

7>

I'm saying that any source that uses "interstellar planet" isn't going to be an authoritative one. People can use whatever terminology they like, but using non-standard terminology is indicative of not being familiar with the field. There's no way Mr. Durick could have known this, of course, and I don't blame him for not picking up on the clue.

9timspalding
Jan 8, 2013, 8:26pm

Do real astronomers talk about the Eye of Sauron? :)

http://www.wired.com/wiredscience/2013/01/fomalhaut-b-confirmed/?cid=5254794

10lorax
Jan 8, 2013, 9:00pm

9>

I think there's a nebula by that name, yeah. Names tend to be pretty ad-hoc, even if terminology for classes of objects tend to be established so that people know that they're talking about. (As a case in point, because "interstellar planet" is not standard terminology, until Mr. Durick posted the link I had no idea if he was referring to extrasolar planets or to free-floating planets. It helps if everyone involved in a conversation uses the same words to refer to the same things.)

11Mr.Durick
Jan 9, 2013, 4:21pm

This, I think, is the article wherein 'quadrillion' is brought up that I was looking for. The interstellar planets here are called nomad planets by astronomers. Rogue planets seems also to be a common phrase.

Robert

12lorax
Jan 9, 2013, 4:52pm

11>

I followed the Wikipedia link and ended up reading the actual MNRAS paper, and I'm no more likely to believe it than I was at the time. The arguments are, as I said, wild extrapolation without data, although the "interstellar planet" nomenclature seems to be the fault of the publicizers rather than the scientists.

I just realized that Mr. Durick may not know that I'm a former astronomer, and in this narrow area I actually do know that I'm talking about.

13AnnaClaire
Modifié : Jan 9, 2013, 10:05pm

Wait, an interstellar plant? As in astrobotany?

Edit: I see now that Mr.Durick also caught the typo. (Don't even ask about the time I almost sent what called itself an "e-maul.")

14DugsBooks
Modifié : Jan 17, 2013, 10:27am

If the rogue planets are that common would a possible scenario be to find a smallish one heading in an advantageous direction for interstellar exploration. Set up camp on the lee side of the planet{iod} with self replicating ion drives and use the planet for shielding as you accelerate toward a significant percentage of the speed of light velocity ?

Also I guess this increase the possibility of a "Nemesis" rogue brown dwarf or slightly smaller headed in our direction!

Dyson tree, possible interstellar plant?  Traveling with it own brown dwarf energy source? ;-)

http://www.orionsarm.com/im_store/dysontree1248379918.jpg

15timspalding
Jan 9, 2013, 11:00pm

>14 DugsBooks:

Sounds like a good idea to me. The only problem is, if it were a good idea, with the age of the universe, we'd already have been visited by joyriding aliens. :)

16lorax
Jan 10, 2013, 9:16am

Unfortunately, most of the rogue "planets" - however many there are, and I can see that most people here have firmly latched onto the "One person with a PhD in a semi-related field speculated about a conceivable upper limit, so that is obviously the correct number" line of thought, by any reasonable formation mechanism (also something that the much-hyped paper everyone's going wild about lacks) would be 'planets' only by a technicality - a few times larger than Jupiter, but below the deuterium-fusion limit (called 'deuterium-burning' by astronomers, but that's confusing to the general public since it's a nuclear reaction, not a chemical one) so there aren't brown dwarfs. Somewhere along the line as you decrease in mass, the mechanism by which stars and brown dwarfs form stops working; you can't form something the size of Earth the same way you form something the size of the Sun. So larger free-floating planets, the sort we can actually see -- the smallest that we have decent data for is between 4 and 7 Jupiter masses (paper) (press release) may form independently, the same way that stars do (though the paper doesn't make any claims about the formation mechanism for this particular object), but lower-mass free-floating planets (of which none have ever been found, though they'd be harder to find) would have to be ejected from solar systems after having formed as planets around stars. This is not uncommon in planetary-formation models - most of the models for forming the "hot Jupiters" that were the earliest-known extrasolar planets have them ejecting any planets that were initially between them and their parent star as they migrate inwards - but obviously this would even in the most extreme scenarios only produce the same order of magnitude of free-floating planets as of stars. There's a plausible estimate that there are about twice as many free-floating Jupiters as there are stars, based on microlensing results (abstract), which would mean the same order of magnitude for free-floating Earths would be plausible. That abstract makes this key point: An abrupt change in the mass function at about one Jupiter mass favours the idea that their formation process is different from that of stars and brown dwarfs. They may have formed in proto-planetary disks and subsequently scattered into unbound or very distant orbits. The 'quadrillion' claim requires this not to be the case - they're continuing a line of "how many objects are there of a given mass" that is well-known for stars and brown dwarfs, which tells us interesting things about how stars form, down through planetary masses all the way through comets, which is shockingly naive.

There is just no way that the 'quadrillion' number is remotely plausible. I'm sorry. Y'all can believe it if you want, but it defies all the evidence. Personally I think the actual claims that are supported by real science are pretty damn cool, but I'm obviously in the minority.

17DugsBooks
Modifié : Jan 10, 2013, 11:17am

Thanks for technical comments and links Lorax - I always appreciate a free education.

18Carnophile
Modifié : Fév 22, 2018, 7:36pm

>15 timspalding: The only problem is, if it were a good idea, with the age of the universe, we'd already have been visited by joyriding aliens.

Maybe they were already here, but they were just passing through.

(Pdf file.)