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(Slate)   Astronomer finds a star as cold as ice. No word on whether it's willing to sacrifice our love   (slate.com) divider line 30
    More: Cool, failed star, Right Next Door, Philip C. Plait, Infrared Survey Explorer, astronomers, Gemini Observatory, rogue planets, Proxima Centauri  
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2637 clicks; posted to Geek » on 26 Apr 2014 at 5:13 PM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



30 Comments   (+0 »)
   
View Voting Results: Smartest and Funniest
 
2014-04-26 01:07:27 PM  
Subby has staaaars in his eyes,
 
ZAZ [TotalFark]
2014-04-26 01:16:33 PM  
Some people might argue that because brown dwarfs can't sustain fusion in their stars they aren't really stars.

Unless there has been some new discovery in star formation physics, both the "fusion" and "formed like a star" criteria for star-ness exclude objects in this mass range.

Here is the discovery paper: http://iopscience.iop.org/2041-8205/786/2/L18.
 
433 [TotalFark]
2014-04-26 01:32:48 PM  
Check your star maps, astronmers, they've seen it before - happens all the time.
 
2014-04-26 02:02:01 PM  
Submitter wants greenlight paradise, but he's going to pay the price, I know

/not a foreign concept
 
2014-04-26 02:09:15 PM  
i1.ytimg.com
Subby's head games are giving me double vision and it feels like the first time.
 
2014-04-26 02:20:34 PM  
static.tumblr.com

Probably should ask this guy about it

www.doctorwhoreviews.co.uk
 
2014-04-26 02:29:42 PM  

Darth_Lukecash: [static.tumblr.com image 500x266]

Probably should ask this guy about it

[www.doctorwhoreviews.co.uk image 600x337]


Damn, faster than me.
 
2014-04-26 04:08:09 PM  
Well I would do anything for love... but I won't do that
 
2014-04-26 04:26:15 PM  

The Bad Astronomer: This goes back to my long-standing point about Pluto and planethood status: Trying to define a term like "planet" or "star" will just get you into trouble at the borders. It's best not to define them, and instead use them as concepts, like "continents".


Of course, none of these demarcations exist in nature. They're just labels and categories we pattern-seeking humans apply to things in order to better understand them. The Universe is not so easily divisible (I always like to say that it's analog, not digital). In the future we will find even weirder stuff necessitating further revision of the way we classify things.

What we should always be aware of is to NOT fall into the trap of confusing our definitions of reality as being reality itself (as what happened with the Pluto fiasco). They aren't -- they're just anthropocentric placeholders and judgment calls. They don't change what we are observing, and the Universe doesn't care what we call its contents and it's under no obligation to validate our models at any rate.
 
ZAZ [TotalFark]
2014-04-26 05:12:19 PM  
Ishkur

Our definitions of dwarf planets, rocky planets, and gas giants, of stars and planets, line up with minimums of distribution functions. They are natural divisions even if they may not turn out to be perfect divisions.

For example, the peak of the stellar initial mass function is above the minimum mass to support hydrogen fusion. At the low masses where the line between light stars and heavy planets is drawn there are not many of either.

There are theoretical reasons to expect a greater number of definite stars and planets than ambiguous cases. A tiny cloud of gas will not collapse under its own gravity. (See: Jeans mass.)
 
2014-04-26 05:26:01 PM  

JoieD'Zen: Subby has staaaars in his eyes,


Did the moon break his heart?
 
2014-04-26 05:35:18 PM  
So it's cooler than being cool?
 
2014-04-26 05:45:11 PM  
Is there any chance it was ejected from the Solar System?  How cool would that be?
 
2014-04-26 06:00:03 PM  
I think we should do a Kickstarter to move Pluto into orbit around this star so we can have a non planet orbiting a non-star.
 
2014-04-26 06:05:12 PM  
Xenu?
 
2014-04-26 06:33:33 PM  

farkingismybusiness: [i1.ytimg.com image 480x360]
Subby's head games are giving me double vision and it feels like the first time.


Quit being an Agent Provocateur.
 
2014-04-26 07:02:14 PM  

farkingismybusiness: Subby's head games are giving me double vision and it feels like the first time.


I think you're hot blooded

/check it, and see
 
2014-04-26 07:20:42 PM  
farkingismybusiness: [i1.ytimg.com image 480x360]
Subby's head games are giving me double vision and it feels like the first time.


I see you don't need no instructions to know how to rock.
 
2014-04-26 07:42:33 PM  
Can anybody explain whether this means anything about the dark matter enigma? At one point I thought i had an understanding that one of the justifications for dark matter comes from some cosmological models of the origin of matter that are build on assumptions about ratio of masses of distant galaxies to the amount of light they emit. Big ol' stars just floating would seem to justify some more mass in that ratio...
...and some further digging leads me another justification for dark matter: the baryon-photon ratio, a subset of Big Bang nucleosynthesis theory, with evidence for this ratio derived from abundances of stable isotopes of the light elements. Going by the info here, recentish WMAP CMB observations seem to give some reasons to question the status quo working hypothesis.
 
2014-04-26 08:05:07 PM  
I chuckled, subby.

/nerd
 
2014-04-26 08:11:08 PM  

The Bad Astronomer: You could have a planet with, say, 5 Jupiter masses that formed by accretion in a protoplanetary disk, and a BD that formed from collapse with a mass of 5 Jupiters, and if you put them side by side they'd look just the same.


Like trying to distinguish between an adult chihuahua and a lab puppy only by measuring their mass.
 
2014-04-26 08:36:29 PM  

rdyb: Can anybody explain whether this means anything about the dark matter enigma? At one point I thought i had an understanding that one of the justifications for dark matter comes from some cosmological models of the origin of matter that are build on assumptions about ratio of masses of distant galaxies to the amount of light they emit. Big ol' stars just floating would seem to justify some more mass in that ratio...

To make a correction, the original hypothesis of dark matter wasn't to solve a cosmological problem.  What they did was estimate the mass of galaxies based on the starlight, and it turns out that (looking at the Doppler shifts of the spiral arms) galaxies spin way too fast for the estimated mass to hold it together.  The difference was determined to be matter that doesn't emit light, so they dubbed it. . . dark matter.

For others in this thread, rdyb is referring to the theory that the "dark matter" (in that it doesn't emit light) holding galaxies together is MACHOs (massive compact halo objects).  In all likelihood the galaxy contains billions of Earth-sized masses too small, too dark and too far from anything to be detected, and maybe a thousand or even a million comets and asteroids for each rogue planet.  We're finding more stuff all the time but figure that we're really not going to detect a bus-sized rock ten light-years from anything.  Could they be the "dark matter" everyone's looking for?

To answer your question, the mere confirmed existence of rogue planets or brown dwarfs like this one doesn't change anything.  It's been long theorized that the galaxy is teeming with rogue planes, brown dwarfs and other debris, so actually finding them is a pleasant surprise in a "yay we did it" sense, not something that sends scientists back to the drawing board.  Second, dark matter is supposed to comprise of something like 80% of a galaxy's mass (let's ignore dark energy for now).  IIRC they calculated what that would mean if it was in MACHOs and it turns out it would entirely obscure the stars of galaxies.  After all, that is a LOT of junk.  It's a scale issue.  Our Sun hosts hundreds, possibly thousands of dwarf planets and a number of big ones you've heard of AND billions of comets and asteroids, yet Jupiter alone is something like 70% of the mass of the non-Sun part of the system.  The Sun is a thousand times more massive than Jupiter, and as stars go it's only "above average".  Whatever dark matter is, it's probably not the small stuff; it just doesn't add up.  It contributes some, but not enough to give a satisfactory answer.

Finally, the counterpart to the MACHO theory, that dark matter is actually weakly interacting massive particles or WIMPs -- got a huge boost from observations of the Bullet Cluster.  When two clusters collided, the dark matter -- which, being the majority of the mass, does the majority of the gravitational lensing -- traveled unimpeded while the gas and other stuff slowed down.  If the dark matter were MACHOs they'd lag the gas, but the dark matter was ahead of it.  That's far more damning than our direct observations of our neighbors.
 
2014-04-26 08:40:36 PM  
It's a Cold-Hearted Star! (ah!) Look at it's spectral lines.  (oh!) Uh oh, who knows that this implies.

www.thelovecollage.com
 
ZAZ [TotalFark]
2014-04-26 09:08:22 PM  
dragonchild

If MACHOs are planetary mass objects, they should end up in the same place as the stars after a high speed encounter between galaxies. Neither gravity nor impact of gas should affect their motion significantly.
 
2014-04-26 10:10:40 PM  

The Bad Astronomer: This goes back to my long-standing point about Pluto and planethood status: Trying to define a term like "planet" or "star" will just get you into trouble at the borders. It's best not to define them, and instead use them as concepts, like "continents".


Good to see you back Phil!
 
2014-04-26 10:50:04 PM  
Ugh, lots of bad company in this thread.  I'm movin' on.  Gone, gone, gone.


/Can't get enough?
//Go run with the pack
 
2014-04-27 01:45:03 AM  

dragonchild: To make a correction, the original hypothesis of dark matter wasn't to solve a cosmological problem. What they did was estimate the mass of galaxies based on the starlight, and it turns out that (looking at the Doppler shifts of the spiral arms) galaxies spin way too fast for the estimated mass to hold it together. The difference was determined to be matter that doesn't emit light, so they dubbed it. . . dark matter.


This sounds like the very definition of a cosmological problem.
 
2014-04-27 02:21:32 AM  
Killer headline A+
 
2014-04-27 08:45:46 AM  

ZAZ: If MACHOs are planetary mass objects, they should end up in the same place as the stars after a high speed encounter between galaxies. Neither gravity nor impact of gas should affect their motion significantly.

Relative to the stars, anyway.  I might not have been clear because I left the stars out of the explanation.  The stars were really just there for reference, as it's the dark matter they were looking for.  There's the gravity (detected via lensing), the hot gas (detected via x-rays) and the stars.  If dark matter were MACHOs, the lensing should've tracked the stars because, as you say, they'd keep pace with the stars themselves.  If they were WIMPs, it'd be ahead of the hot gas.  The astronomers detected lensing ahead of the gas & stars, implying dark matter was WIMPs.  At least, that's how I understand the Bullet Cluster observations.

stamped human bacon: This sounds like the very definition of a cosmological problem.

No, cosmology is the study of the origin, evolution & fate of the universe.  That galaxies seem to spin too fast to hold together is strictly an astrophysics problem, though any theory that explains the phenomenon can possibly affect our cosmological models.
 
2014-04-27 08:51:21 AM  

Xaxor: Darth_Lukecash: [static.tumblr.com image 500x266]

Probably should ask this guy about it

[www.doctorwhoreviews.co.uk image 600x337]

Damn, faster than me.


Doctor whore views?
 
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