Ring Of Stars Found Around Milky Way

LoPingHo writes "Scientists have found a ring of stars around our galaxy that has previously been undetected due to the faintness of the stars. The article says that it only amounts to 1% of the galaxies mass, but if they are just now finding those, that means there could be even fainter ones there too. Could this be part of the elusive 'dark matter' talked about so much lately?"

Comments

Dark Matter?

[ancukiewiczd]

I always thought that dark matter was perfectly invisible, and not just a large number of very dim stars. Maybe those stars could help account for the missing mass, but measuring at 1% it doesn't seem very likely.

Re:Dark Matter?

[mao che minh]

Dark matter is just the term for matter that we can't detect. It can be baryonic material or even black holes. "Dark" doesn't mean 'invisible' when they use it in that context.

Re:Dark Matter?

[prizzznecious]

Cool baryonic matter not emitting much light has been eliminated from the possibility of accounting for all the "missing mass".

Could you provide some sort of support for that claim?

There are two realms of explanation for the supposed enigma of Dark Matter. One is that matter like these stars have simply escaped our detection; in short, that it is our instruments that are at fault. The other is that our instruments have reached perfection (at detecting the things we can explain), and we've looked everywhere, and, well, supermassive and invisible objects exist all over the place.

The latter is a pretty theory, appealing to the imagination and to the egos of scientists. It's also completely ludicrous as the sole explanation for observed mass/gravity discrepancies. A few years ago, scientists barely thought brown dwarf stars existed. Now we know that they're everywhere, and in all likelihood far more prevalent than scientists currently have the capacity to investigate. What else are they missing?

These things are hard to see across the vastness of space, especially when they emit little or not light. That doesn't mean they aren't there. As .. improbable (coughhackcough) as it might seem to some, it's far more likely that our instruments just aren't strong enough. That's all.

Re:Dark Matter?

[CraigParticle]

Could you provide some sort of support for that claim?

Aside: Really, it's not about the egos of scientists, or the perfection of our telescopes and instruments. Goodness knows, if they were so perfect, we wouldn't be begging for money to build new and better ones! :)

The link that pyrrho mentioned describes the basic reasons why baryons can't be all of the hypothesized dark matter. And since 1996 (when the article was written), the evidence has become vastly more convincing. I'll attempt to summarize.

Sure, we could hypothesize that the Universe is filled with "dim, normal stuff" like brown dwarfs, white dwarfs, lost airline luggage, missing socks, dryer lint... but we're just not able to see them. Fair enough. But there is a limit to this argument for numerous reasons.

• There are not enough baryons in the Universe. The Big Bang only made so many baryons, and this is something we can measure. The limits on the number of baryons in the Universe are quite tight -- only, say, 5% of the mass needed to give the Universe an uncurved geometry.

  Okay, so maybe we just live in an empty, open Universe! But numerous measurements of the curvature of the Universe, in particular recent observations of the cosmic microwave background itself suggest that the curvature is not open but uncurved. So we live in a Universe with plenty of gravitational matter of some form or another. Aside: we are gathering a huge amount of information by looking at the angular sizes of the bumps and dips in the cosmic microwave background, which is fossil radiation from the Big Bang and a few percent of the static you see on your TV when tuned to a blank UHF channel. This page shows what the CMB power spectra (that is, how many inhomogeneities occur at a given angular size) look like, and how changing various cosmological parameters has an effect on the spectrum you'd expect to see. Try out changing the baryon density -- the effect is quite pronounced. It also says that the Universe has the number of baryons that Big Bang theory says it should have.

• Even if we can't see brown dwarfs (or basketballs, for that matter) by their reflected light, we CAN infer their existence by their gravitational interactions with light, i.e. gravitational (micro)lensing. It's not that we "haven't looked hard enough" -- but rather that "if the Universe was full of brown dwarfs, there'd be tons of observable microlensing events". But microlensing events are exceedingly rare. In this case, the null result is interesting, because it highlights that baryonic matter is not as prolific as we want/need!

So this makes us all feel a bit uncomfortable, because either some of the fundamental tenets of cosmology are flawed (even though they explain nearly all of the observable Universe, right down to the abundances of the elements and the large scale structure of galaxies and the cosmic microwave background, the recession of galaxies etc.) ... OR ... the Universe is mostly filled with matter what is unlike anything we yet know how to explain.

It's going to be a fun ride! :)

Real explanation

[doogieh]

This ring of stars is the result of a collision, as can be easily proven by observation of Bugs Bunny upon contact with an anvil.

As for the missing mass, that's due to Elmer FUD.

Ring of stars

[CaseyB]

Sounds like they've discovered a Kemplerer Rosette. :)

Re:Ring of stars

[merlin_jim]

Sounds like they've discovered a Kemplerer Rosette [burtleburtle.net]. :)

I believe that a Kemplerer Rosette is characterized as being a stable gravitational configuration of bpdoes orbiting a single point at similar distances and speeds in such a way that all bodies are equidistant, and is further characterized in that one could envision a regular polygon of n-sides, where n is the number of bodies, and if one vertex is mapped to the location of one body, and the center of the polygon is mapped to the common orbit location, then all other vertexes will correspond to locations where the other bodies reside.

This ring of stars, being randomly located, would not qualify. In addition, a Kemplerer Rosette is only stable against small perturbations; if the bodies are far enough apart that other gravitational influences grow large with respect to their gravitational influence on each other, then it is no longer stable.

I don't get it

[Cyno]

Isn't dark matter simply matter that doesn't emit light? If stars get formed by huge clouds of gas that eventually create so much heat and pressure that it starts a process of fusion, then its more than likely all this dark matter we are talking about is just that, dark matter, dirt, whatever you want to call it. It isn't anything significant other than it isn't radioactive, which is a good thing, IMO.

Re:I don't get it

[jbischof]

No, dark matter is something causing gravitational pull that we cannot locate. It is not neccesarily matter that doesn't emit light.

Nobody knows what dark matter is yet, but there are lots of guesses.

Re:I don't get it

[Christopher Thomas]

Isn't dark matter simply matter that doesn't emit light? If stars get formed by huge clouds of gas that eventually create so much heat and pressure that it starts a process of fusion, then its more than likely all this dark matter we are talking about is just that, dark matter, dirt, whatever you want to call it.

It turns out that the measured effects of dark matter mean that only a small fraction of it can be "normal" matter. Look up "baryonic" and "non-baryonic" dark matter on Google for more information on the subject.

The "normal" component could be anything from white dwarf stars to brown dwarf super-planets to micro black holes to dust and gas, or all of the above. However, that still leaves most of the mass as something else.

Re:I don't get it

[The Only Druid]

No, some matter could (according to both relativity and quantum physics, not to mention string physics) have not only negative energy (and thus negative mass), but also travel through different dimensions in different directions.

Tachyon's, the result of solving Einstein's equations for an object travelling faster than light, would have negative mass (but positive energy) and would travel backwards through time. Before you say it, yes its impossible to accelerate to lightspeed. On the other hand, there's no reason a certain class of particles couldn't come into existence at faster than light speeds.
Kaluza-Klein particles, a recent idea, are another option for dark matter. They're so-named because they're believed to travel primarily through the 9 folded-up dimensions of string theory. (Kaluza and Klein devised the mathetical methods and theories which explain how string theory functions in an 11 or 12 dimensional universe). These particles, but flitting in and out of "our" four dimensions would only be weakly interacting (and thus qualify as dark matter) but would interact quite powerfully when they were present (due to extremely high mass).

Re:I don't get it

[Anne_Nonymous]

Actually, the universe is made of two types of matter: light matter, and dark matter. Light matter is generally acknowledged to be more savory and delicate in flavor. It can be dry, but when cooked properly, retains the universe's natural juices. Light matter is found in the breast and wings. Dark matter, on the other hand, is found on and near the drumsticks of the universe. It contains a higher percentage of fat and is therefore, often more flavorful and gamey.

Go ahead, ask me another one...

Re:I don't get it

[zmooc]

Before you say it, yes its impossible to accelerate to lightspeed.

Only according to a theory that assumes c is a constant while it is not - it's getting slower al the time. It's called CDK. This may also very well mean the red-shift calculations used to determine the speed at which galaxies move away from us are totally wrong which may therefore mean that the universe is not expanding at all (or at least not that fast) which makes the mass-calculations bullshit as well and may very well mean dark mass does not exist and there's just nothing out there. This is a good read about it: http://www.ldolphin.org/bowden.html

Not Dark matter

[jbischof]

Unfortunetly this could not account for dark matter.

The reason scientists believe that there should be dark matter is because of the fact that the stars on the edge of galaxies move faster than they should. According to the measured amounts of mass in a galaxy, the stars on the edges would fly out of orbit at the speeds they are going.

Extra mass on the outer fringe of a galaxy could not contribute to this lack of gravity. I am pretty sure that more than 1% of the galaxy's mass is missing also. But I suppose this goes to show that we never know as much as we think we do.

Checkout the everything 2 node on dark matter for more information.

Space and Science can explain anything...

[screenbert]

Mom used to tell me, "Becuase I'm the mom and your the son and that's why"

I explained to her logically using space and science that "You're right, You're the mom and I'm the son and we all know the world revolves around the sun".

Likewise invisable stars explain dark maatter.

Dark Matter

[FuryG3]

Somewhat offtopic:

In the world of diagnosing dark matter, scientists think that neutrinos could make up a good hunk of it.

http://www.aip.org/enews/physnews/2002/split/586 -1 .html

I heard about this on NPR's Talk of the Nation: Science Friday last week. What i heard was: in order for neutrino's to change from one type to another, they must have a small ammount of mass, and even if you give neutrino's a tiny tiny tiny ammount of mass, they suddenly account for a good hunk of the dark matter out there.

I know nothing about any of this, so if someone could go into further detail it'd be great.

Re:short answer

[yobbo]

Could this be part of the elusive 'dark matter' talked about so much lately?

Yes.

Hey look at me, I provided an answer with absolutely no evidence to back it up, gimme a +1 informative!!

Re:short answer

[Computer!]

Could this be part of the elusive 'dark matter' talked about so much lately?

I was wondering who was talking about dark matter so much lately, and it was you two! Problem solved.

Re:hmmmm

[jmb-d]

"Scientists have found Ringo Star around our galaxy"

The tipoff was that it had trouble maintaining anything other than a straight 4/4 rhythm.

This Just In ...

[handy_vandal]

... the universe is "really, really big."

Re:What if it's the other way around?

[merlin_jim]

In the article: "If the ring turns out to be due to a satellite galaxy, it would mean that we are seeing the Milky Way cannibalizing a small galaxy and incorporating it into the galactic disk..." But what if it's the other way around?

Wouldn't that be like the researcher who, several years ago, proposed the theory that The Odyssey was not written by Homer the blind poet but was in fact written by a completely different blind poet named Homer?

Re:short answer

[merlin_jim]

Could this be part of the elusive 'dark matter' talked about so much lately?

Yes.

Most scientists believe that dark matter makes up 80 - 95% of the total gravitational mass of the galaxy, and probably the universe.

Dark matter is simply the term given to matter that we haven't observed yet, except indirectly through its gravitational effect.

This is certainly some portion of the dark matter. But I wouldn't say a significant part, or even a part really worth mentioning. While the dark matter is almost definitely comprised of several different sources, it seems certain to me that there is an entire class of gravitational objects that we have yet to observe, and this is the cause of the dark matter. Whether its dark stars, black holes, heavy neutrinos, or some even more strange and cosmic form of matter I don't know. It could be all of those and more.

Point being, if the dark matter within the Milky Way is only 80% of the mass of the galaxy, and not say 95% as some researchers suggest... this would make it 400% of the mass of the observed portion of the galaxy. These stars are, according to the article, 1% of the mass of the (previously) observed portion of the galaxy. Which makes them 0.25% of the mass of dark matter required to account for gravitational effects that are otherwise unexplained. If dark matter turns out to be a significantly larger percentage, such as 95%, then these stars only account for .05% of the mass of dark matter.

For those who question the value of determining either the cause or the exact amount of dark matter in the universe, this debate is pivotal for determining the final fate of the universe. So far our calculations of the total mass of the universe, including the dark matter, are riding the knife-edge required to make the universe exactly stable. If there is a little more mass than this, then the current expansion of the universe will one day reverse, until the universe contracts back to a singularity. If there is a little less mass than this, then the current expansion of the universe will continue infinitely.

This is all according to current theory on the creation and eventual fate of the universe and is subject to change with brilliance, genius, and persperation.

Re:short answer

[Anonymous Coward]

Now try to find the elusive gray matter.

Re:obTolkien

[kilonad]

Obligatory Tolkien

Is that kind of like token Tolkien?

...mmm, the smell of burning karma.

here's the problem

[rebelcool]

even if you filled the outside of the galaxy with a shell of dead rock, it wouldnt account for the missing mass. There is *alot* of missing mass. Plus itd be easy to spot that, because little light would get through it.

Others suggest alot of neutron stars spinning around out there, also not likely. We'd have noticed them, either by an inordinate amount of nearby pulsars, or simply from gravitational lensing. Same goes for dead hunks of carbon. To make up the missing mass, there would have to be many of these things. And with many of them, the chance of spotting several would be high.

The macho theory suggests there COULD be a *few* but *extremely* massive objects wandering around out there. Something like supermassive blackholes, or something else. If there were a few, and they emitted no light (likely), then they'd be easy to miss.

The other theory suggests that there is some kind of exotic matter which we haven't discovered yet that emits no known form of radiation, but may indeed generate gravity. This is also possible, as the newly discovered 'dark energy''s origins are also unknown. The confirmation of dark energy (which is recent) is what drives the expansion of the universe, and is indeed some kind of 'anti gravity'. Very interesting, but very strange. And we have no idea where the hell it comes from.