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

Thanks!

[geekoid]

I was wondering where I put those.

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?

[spanky1]

I think it is called dark matter because there should be more matter in our galaxy than is currently visible/detectable. But finding more visible matter would seem to reduce the need for as much "dark" matter.

Re:Dark Matter?

[pyrrho]

Dark matter must either be some strange particle, or must be a change in the laws of gravatation (the latter is considered not likely).

Cool baryonic matter not emitting much light has been eliminated from the possibility of accounting for all the "missing mass". A more promising idea is something non-baryonic but massive, like a massive neutrino. Well, more actually than just one of those.

For more information try google "non-baryonic dark.matter" or "baryonic dark.matter".

It's amazing really, astronomy is still at the forefront of physics here on earth, when they figure out what dark matter is and can reproduce that here on earth, it's likely to be one of the biggest things in physics (for a while).

Re:Dark Matter?

[Anonymous Coward]

As long as the dark matter doesn't try to destroy the sun, I don't care.

See Ring or Vacuum Diagrams by Stephen Baxter for an explanation.

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?

[pointym5]

I thought it couldn't be baryonic matter under most good-candidate expansion theories.

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?

[reverseengineer]

Dark matter doesn't necessarily need to be completely invisible, just rather hard to detect. Its exact properties depend on the sort of dark matter candidate you are considering. The two general types of dark matter candidates are MACHOs- MAssive Compact Halo Objects, which are relatively large (but very small on a galactic scale), dim objects such as gas giant planets, brown dwarfs, and black holes. Many of these object emit faint radiation, but are completely washed out by brighter objects nearby, or are merely too dim and too far away. The major method for searching for MACHOs is gravitational microlensing- if a MACHO passes between us and a faraway star, its gravity should bend the star's light like a lens, making it appear temporarily brighter, with the intensity chance and duration being indicative of the mass and velocity of the MACHO. The other major candidate is that an invisible cloud of massive particles surrounds our galaxy. These particles would have to have a gravitational field (i.e., nonzero mass), but must be extremely nonreactive- dark matter seems to have effects on a galactic scale, but seems to be undetectable or nearly undetectable on earth. Some physicists think that no known particle meets this description, and are looking for WIMPs (Weakly Interacting Massive Particles) I believe these were named before the MACHOs, btw. As their name implies, they interact with normal matter very weakly- they can pass though many miles of solid matter (like the entire earth) and emerge unscathed. Detection efforts usually involve sensitive experiments carried out deep underground. There are other physicists who believe the dark matter has been located already- in the humble neutrino. Results from the Super Kamiokande neutrino detector strongly suggests that the neutrino, long believed to be massless, has a very small but finite mass. The exact mass is unknown, but should exist because neutrinos oscillate freely among its 3 varieties (electron, muon, and tau), which could only occur if the neutrino had a mass. This mass is very, very small- much smaller than that of an electron, even, but there are so many neutrinos that even a tiny mass would mean that neutrinos make up the vast majority of matter in the universe.

Re:Dark Matter?

[pyrrho]

first off, to not pose: I'm a software engineer, not an Astronomer, though my statement of what was "considered less likely" is based on what I've been recently told by astonomers I work with.

This was an interesting read, though as I said, it was found just through a google search.

I admit it's all speculation and half of it I don't claim to actually understand to the level of making a good argument.

But think of a couple things. One, it's not about perfect instruments, it's about instruments that are good enough to see what you are looking for. If I have ten marbles in a dish, but it weighs as much as twenty... I know I should see the extra marbles if they are ordinary marbles. We are not talking about a little bit of missing mass, we are talking about a huge bit of missing mass.

Another, it's about what you do see. For example, there cannot be a diffuse gas in the galaxies to cause this effect because (a) it would not have enough mass and (b) you could see absorption lines of the gas.

It's not like we are looking for something small, remember... we're looking for something big! Something with a lot of mass that for some reason doesn't or can't glow.

And of course I agree that relatively exotic dark matter cannot be the only source of dark matter, some is just undetected baryonic matter. The rub is that it doesn't seem there could be enough of that to account for all the dark matter, a significan portion looks to be something exotic or at least non-baryonic.

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! :)

Re:Dark Matter?

[prizzznecious]

That's really very interesting; I hadn't realized those aspects of the problem. Thank you for such a lucid explanation.

Re:Dark Matter?

[Alsee]

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.

Nope. When the dark matter problem was first discovered they thought (hoped) that it was just normal matter that we can't see. It isn't. This post provides a pretty good explanation.

Note: that post only lists a few of the reasons. There are several others. Either we've made a whopper of a mistake in our understanding of physics or more than half the mass in the universe is "something else".

-

Re:Dark Matter?

[Lasalas]

So basically, what you're saying is that dark matter purely exists to balance theories, and without it, a lot of science wouldn't make sense.

Re:Dark Matter?

[CraigParticle]

That's essentially it, yes.

Dark matter has been invoked to explain puzzling observations, within a theoretical framework that has proven pretty trustworthy for everything else so far. Either dark matter is real, or the framework needs a facelift somewhere. Jury's still out on that one.

Let's highlight one example. Consider first the motion of the planets around the Sun, which itself comprises most of the mass of the Solar System. The innermost planets like Mercury and Venus are whizzing around at high speeds to maintain their close orbits. By the time you get out to Neptune or Pluto, they're just crawling along, since they are far away from the Sun. This is all nice and reasonable.

Now when you look at (spiral) galaxies, most of their luminosity (and presumably mass) comes from their inner regions, so you might expect the same kind of rotation pattern; the inner regions would have high rotational velocities, and the outer regions would rotate slowly. But this doesn't happen -- in fact the outer regions tend to rotate every bit as fast as the inner regions! But there's no luminous matter out there to support such rapid motion! There must be something out there that has huge gravitational impact, but without emitting any kind of light. Hence one invocation of dark matter. There are others, but the theme is largely the same.

Some folks understandably find the notion of dark matter distasteful, and are working on modified theories of gravity that have 'appropriate' characteristics on the scale of an entire galaxy. But many consider those "modified gravity" arguments to be unconvincing, ad hoc and distasteful in their own way -- so far.

What is important is that we are learning more and more about our place in the Universe, and uncovering new puzzles that we don't yet understand. And that's what makes it fun. :)

Re:Dark Matter?

[mike77]

Dark matter is just the term for matter that we can't detect.

Actually this is incorrect. Dark matter can be detected, just not in the way we are accustomed to thinking about. We know it's there due to the effect of gravity. We cannot "see" it because it is neither emitting light, or reflecting light. Why is a damn good question, but if it was truly undetectable, why would we be worrying about it to begin with?

Re:Dark Matter?

[JCholewa]

> 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!

...wait. Isn't dark matter supposed to still have mass and gravity? So any dark matter of sufficient size would cause microlensing, not just baryons, no?

-JC

Re:Dark Matter?

[Anonymous Coward]

If you assume that the missing matter is barionic then the predicted element abundances are all wrong.

short answer

[Anonymous Coward]

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

no

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:short answer

[Old Ike]

Could this be part of the elusive 'dark matter' talked about so much lately? 42. I win.

Re:short answer

[gewalker]

3 points for concise and correct answer, -1 for missing important details left out.. Not quite so short answer follows:

No, because dark matter is thought to be the explanation for galaxies moving apart faster than conventional explanations, so dark matter is assumed to exist and cause a negative gravitional attraction (negative mass, not anti-matter), to explain observed behavior.

Even if you assume postive vs. negative matter is not the issue, the ring around the galaxy is much to small in mass to make much of a difference anyway (much smaller that assumed dark-matter).

Re:short answer

[Anonymous Coward]

The real question we should be asking is:

Must every slashdot science story submission end with a completely uninformed and stupid question?

Re:short answer

[The Only Druid]

You're somewhat incorrect. What you refer to - matter with negative energy or "quintessence" - is not what is meant by dark matter. It is "dark energy". I know the name seems to imply similarity or identity, but they're different.

Dark matter is the [largely] undetectable matter that is proposed to contain a significant portion of the mass of the universe; the mass which is unaccounted for by visible matter. There are three main [current] theories about this:

MACHOs. I forget what the acronym stands for, but these are essentially hugely massive particles which are still small. As such, they account for a significant amount of mass without occupying much volume in space. This lack of significant volume (and their relative seperation) makes them difficult to detect.
WIMPs. This acronym was chosen to compete with MACHOs, actually, in a fit of playfullness by scientists. It stands for Weakly Interacting Massive Particles. These are actually quite similar to machos, but are formulated differently mathematically.
Massive neutrinos. Without getting too much into theory, there are many types of neutrinos. If some of them are at all massive (and current experiments suggests that they are) then their massive numbers could account for a significant amount of the missing mass.

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:short answer

[EmbeddedJanitor]

I was wondering who was talking about dark matter so much lately,

Naah, used star salesmen. "No sir, the star ain't broken - it's one of them dark matter stars, all the rage in astronomical circles"

Dark matter is just the fudge factor to try make theory fit observation - like the filler putty I always seem to need when doing carpentry or the "other" slice you always seem to need on a pie chart.

Re:short answer

[Anonymous Coward]

Now try to find the elusive gray matter.

Won't find any on /.

Re:short answer

[Anonymous Coward]

Isn't the quintessence, or dark energy, supposed to be the modern term for Einstein's cosmological constant?

And if these are faint stars, they wouldn't be that, because they would have the property of attracting matter rather than repulsing it.

Re:short answer

[Anonymous Coward]

Yes, quintessence (dark energy) is almost synonymous with the oft-dismissed cosmological constant.

Note that there's a minor difference: Einstein was proposing the constant as an unknown entity, something that he didn't understand and was merely proposing for the sake of solving an equation. It was inspired by a desire to have a steady-state universe be possible, not to mention that it made certain formulae easier to solve.

Quintessence, on the other hand, is a name ascribed to what seems to be [the source of] a detectable phenomenon: the acceleration of the expansion of the universe.

In other words: the CC was postulated to make the equations look better, without measuring the universe whereas Quintessence (dark energy) is postulated to explain a measured aspect of reality.

(btw, this is Druid, i'm just posting from a buddy's comp)

Re:short answer

[MillionthMonkey]

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

>Yes.

I vote no. Stars are luminous and dark matter is not luminous by definition. This could be said to be part of the "missing matter", but not the "dark matter". Argumentum ad lexicon, QED.

Anyway, isn't dark matter supposed to be a hypothesized explanation for why stars in spiral arms are orbiting the centers of galaxies more quickly than can be accounted for by the observed abundance of luminous matter? I'm not familiar with the gravitational properties of a ring-shaped mass distribution, but a ring of stars surrounding the outer rim of the galaxy seems to be in the wrong place to have any explanatory power for the high orbit velocities of stars that are well within the ring. You want to find something heavy that's within their orbits.

Only 1%?

[dzeaiter]

But 1% is still quite a bit. Not trying to sound smart, just out of curiosity: but why weren't these discovered before?

Re:Only 1%?

[jpt.d]

maybe for the reason the slashdot blurb said that you are replying to

Re:Only 1%?

[Anonymous Coward]

Hey, at least he read the headline.

It's a start. Maybe eventually, he'll move up to reading the blurb, and then *gasp* god forbid, actually reading the article!

Re:Only 1%?

[nickclarke]

> But 1% is still quite a bit.

not when you look at the area of the ring compared to the area of the rest of the galaxy.

See the picture in the bbc article on the same subject:
http://news.bbc.co.uk/1/hi/sci/tech/2632 709.stm

obTolkien

[Xunker]

Obligatory Tolkien (consider yourself warned):

...one ring to orbit them all and in the darkness bind them....

Re:obTolkien

[kilonad]

Obligatory Tolkien

Is that kind of like token Tolkien?

...mmm, the smell of burning karma.

Re:obTolkien

[Mithrandir]

oh, it's a Token Tolkien Ring....

Almost as good a The Real Thing(TM)

[groan]

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.

Can't be dark matter

[Anonymous Coward]

On a cosmological scale the dark matter cannot be baryons. There may be room for a disk of baryons to 'fix up' galactic rotation curves
and not muck up the cosmological mix, but I cannot recall.

dark matter

[1000101]

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

um, no.

Re:dark matter

[EvanED]

How is this redundant? The other answer just said "no".

Re:Dark Matter

[freeweed]

I've personally never been able to understand how neutrinos DON'T have mass. I copped out of physics after 2 years, so I missed most of the good math, but... ..since mass = energy, and neutrinos definitely have energy (else how could we measure them? how could they possibly interact with other particles, however weakly, if they didn't?), neutrinos have mass.

Any physics majors out there?

Re:Dark Matter

[Fyz]

A photon is an example of a particle with energy, but without mass, and the neutrino could have been related. Also, the somewhat famous equation E=mc^2 , which is a contraction of a bigger formula(which I forget), also predicts that the only particles travelling at the speed of light will be massless ones. It allows for these having energy.

Re:Dark Matter

[Fyz]

Neutrinos cannot be the dark matter we are talking about here.

The reason is that our problem at hand is within the galaxies: they seem to be spinning much to fast when comparing them to the observable mass. About 90% is missing.

However, since neutrinos are so goddam fast, they aren't "loyal" to any galaxy, and are almost certain to have an equal density, all over the universe. This, of course, means that the resultant gravitational pull will be zero, anywhere you stand.

So neutrinos won't give us an explanation for galactic dark matter, but it helps toward explaining COSMOLOGICAL dark matter, where the subject of gravitational pull is the entire universe.

Re:Dark Matter

[p3d0]

Obviously they mean "rest mass". That is, the mass when the particle has zero velocity.

Re:Dark Matter

[Anonymous Coward]

Well, except for the whole argument that photons might have mass afterall... but...

A Google search on the mass of a photon leads to a lot of pages that discuss that to a great degree.

It is almost certainly impossible to do any experiment which would establish that the photon rest mass is exactly zero. - LINK

Re:Dark Matter

[Anonymous Coward]

I'm no astrophysicist here, but this is how I understand it:

There are three types of neutrinos: electron, muon and tau, each having a different characteristic mass and energy spectrum. The experimentally measured flux of solar electron neutrinos based upon the solar nuclear fusion reactions turned out to be too low by ~50% based on the theoretical GUT and QED calculations. As a means of explaining the apparent discrepancy, it had been postulated that neutrinos are capable of "oscillating" between types over distance and time, thereby affecting the number of measured events (the experimental measurement being limited to certain energies). However, theory suggests that in order to oscillate, the neutrino must have mass.

Ingenious experiments now seem to confirm that what was once considered a massless particle does indeed have mass, albeit vanishingly small.

Since neutrinos are produced in stellar fusion reactions and supernova explosions, etc., in very great quantities (the flux here on Earth is estimated to be over 10^10/cm^2/sec), they would be expected to be in a higher density in the vicinity of galaxies, and thereby could account for a large part of the "missing matter" holding galaxies together.

I think this is what the NPR story was referring to ... but maybe not.

A couple of links:

Physics Web articleon neutrinos.
Super-Kamiokande at UC Irvine Neutrino page.
UniSci article on oscillation.
The confirmation of Solar Fusion by neutrino detection 2002 Nobel Prize press release.

Re:Dark Matter

[Anonymous Coward]

GREAT! Google has pages that defy special relativity!

Sorry, but have you actually READ any of those?

Would you like fries with your crackpot theories?

Re:Dark Matter

[KKin8or]

I believe WIMPs and MACHOs are the (theoretical-- I don't think either have every been found) particles that are one of the possible explanations of dark matter.

WIMP: Weakly Interacting Massive Particle
MACHO: Massive Compact Halo Object

Other theories include massive black holes at the centers of galaxies, lots of cosmic dust, etc. etc.

Re:Dark Matter

[KKin8or]

I will correct myself: a MACHO is not a particle, but just a general term for stuff in the halo of a galaxy that's hard to see, like white dwarfs, neutron stars, and black holes. So I guess this ring of stars could possibly be considered a bunch of MACHOs.

Re:Dark Matter

[FuryG3]

As fast as they are, you would think that they would be in *much* higher qantity near an extremely large cluster of stars, like say a galaxy, even if they do travel beyond them. It's safe to say that even though light zips around, it's much brighter inside a galaxy than it is outside.

Re:Dark Matter

[Fyz]

Even if you're right, the reason for this would be because the stars and other sources of neutrinos are spewing them out. And these neutrinos can not be more massive than the stars that generated them.
The fact is, neutrinos are EXTREMELY abundant, but they are about as isotropic as the background radiation.

Ring of stars

[CaseyB]

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

Re:Ring of stars

[coolgeek]

Whew! I'm glad I actually read the page you linked. Thanks to my slight dyslexia I thought the page would be about what Hogan's Heroes used to do to Colonel Klink.

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.

Re:Ring of stars

[Anonymous Coward]

Way to copy that last statement out of your friend's thesis!!!

Re:Ring of stars

[Anonymous Coward]

OK, I'm an idiot, but this is what I have a question about that I can't get a straight, informed answer from anyone IRL. So I'll submit it to Slashdot people to explain it, Brief History of Time style, to the teeming masses.

1. There is a finite amount of mass in the universe (if you believe Hawking.) Finite numbers always worry me when it comes to Physics. Is there any reason why the number is finite?

2. Is there any reason why this PARTICULAR number (or any other finite number) was 'chosen?'

3. I've heard that the reason why matter exists, in a world where the Law of Conversation exists, is because all matter has anti-matter which effectively cancels out the matter. Such that if matter were to collide with anti-matter it would leave only energy. My question is, if matter collides with anti-matter you only leave energy. Why does only having energy, and here I'm thinking quanta, though I don't really know what it means, mean that matter + antimatter = nothing if you still have energy?

Re:Ring of stars

[some guy I know]

1. I don't know.
2. I don't know.
3. I don't know.

I hope that this has been of some help to you.

Re:Ring of stars

[Anonymous Coward]

After checking out that site, could the unstability of the 48 earth system be due to floating point errors in the program? It is after all witten in Java...

Just a thought.

Re:Ring of stars

[MrGeetee]

1. The Universe is finite[1] and there are parts of the Universe that we know to be devoid of mass[2]. The mass in the Universe must therefore be finite.

2. Take a sample region of the Universe. Tally up the amount of visible mass. This gives you a density. Multiply this by the known volume of the Universe[3].

3. Matter is energy. Energy is matter. If antimatter existed in the same quantities as matter, there'd be no you, no me, nothing, nada, rien. Fortunately, antimatter only exists naturally in small quantities[5][6].

[1] There is only so far a photon can travel from one 'edge' of the Universe so the Universe is essentially finite
[2] ie, vacuums
[3] Assume homogeneity first of course[4] ;)
[4] Not necessarily a bad assumption given the uniformity of the Cosmic Microwave Background
[5] And in physics labs around the world :P
[6] Why antimatter doesn't naturally exist in the same quantities as matter is an interesting question in its own right.

Re:Ring of stars

[merlin_jim]

Way to copy that last statement out of your friend's thesis!!!

Actually I made it up on the spot out of memory. Of course, it helps that I modelled them for high school physics class... that and I read all of Niven's books...

When you said "Ring of Stars"...

[RumGunner]

I thought you were talking about the upcoming Oscars! Go LOTR!

.

Zoomerz?

[Anonymous Coward]

Click here

??? huh?

[_ph1ux_]

Is it just me - or isnt the whole milky way made of stars?

so - they found a ring of stars around a bunch of stars?

Re:??? huh?

[Anonymous Coward]

Ya there are stars all over in space. These goofy astronomers think that every time they find a new one there should be a fucking parade or something.

Re:??? huh?

[billburroughs]

Maybe the dark matter is between their ears?

Re:??? huh?

[Ironica]

I imagine it's like finding out that Australia isn't actually a separate continent, but part of Asia.

It's not just that there's a ring of stars around a disk of stars, but that that ring relates to the disk in a particular way, which makes the galaxy bigger than previously thought.

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

[brian0918]

your concept of dark matter is incorrect. dirt is not dark matter. it emits black body radiation. I believe you are also confusing "radioactive" with "radiative".

Re:I don't get it

[Cyno]

All matter has mass and thus gravity.. er I'd like to think it does anyway. :)

Re:I don't get it

[Anonymous Coward]

yes, but some new type of... something... unlike normal matter, could be causing this gravitational pull.

Re:I don't get it

[jbischof]

right.... all matter has mass and thus gravity. But maybe something as of yet unclassified also generates gravitational pull. That was all I meant.

The dark matter could be due to neutrinos, black holes, WIMPs, planets(non-light emitting matter like you suggested), other universes, or any other number of bizzare things that scientists have hypothesized.

Re:I don't get it

[Cyno]

yes, but does it have to be some new type of something? Have we accounted for all the normal matter in the galaxy yet? I don't know much about these things, but it seems to me like there's probably many moons and hunks of rock in space that our telescopes just can't see. It wasn't until recently that we even thought there might be planets around other Stars in the galaxy. What's next for our divine intellectuals to discover? Moons around those planets? No, say it ain't so.. Did we take into consideration the mass those moons have and their effect on the Stars, when determining how much dark matter exists?

I don't think its really all that mysterious or difficult, or that we're really all that smart. But I could be wrong.

Re:I don't get it

[Cyno]

black holes are cool! Proof that God is a power gamer. :)

Re:I don't get it

[Anonymous Coward]

I don't emit light. Therefore, I am made of dark matter?

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

[Anonymous Coward]

Yes, Yes, I just dropped a large amount of dirt or dark matter, whatever you wish to call it out of my black hole.I think it may have been radioactive, but that might just be the ring of stars flaring up.

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

[Cyno]

Now that's the type of answer I was looking for. *applaud* :)

Still over my head, though. :P

Re:I don't get it

[Cyno]

The main problem with phsyics is lately (within the last 50 years) it has been proving most eastern religions correct in their assumptions that everything does have an opposite, that the nature of the universe is bipolar or something. Matter/anti-matter, positive and negative charge, positive and negative energy, etc. It all adds up to the same thing.. we're growing old.

Re:I don't get it

[p3d0]

I like to give the experts a little credit, and assume that they have ruled these things out already.

For instance---and this is entirely fictitious---suppose the galaxies appear to be ten times too small to hold together given how fast they are spinning, and so you conclude they must consist of 90% dark matter that is moons and dust and such. Then, suppose you measure the gravitational lensing, and find that the effective mass is only half what it should be if it were 90% moons and dust. Well, you'd probably have to conclude it's only 40% moons and dust, and 50% pure magic.

That's the kind of thing these scientists do. If someone with actual facts could back me up a bit, I'd appreciate it.

Regardless, it's easy to dismiss a mystery if you don't know the facts involved.

Re:I don't get it

[Anonymous Coward]

I am not a physicist, but I play one on TV

For all practical purposes, baryons (from the Greek word for heavy) are protons and neutrons. They make up 99.95% of the mass of ordinarily matter. The number of baryons in the universe was established by the big bang, and observations, of things like the ratio of deuterium to hydrogen, establish an upper limit on the number of baryons

Unfortunatley, there are not enough baryons to account for the observed speed of expansion of the universe or the ability of galaxies to retain their shapes. Black holes don't help because their mass derives from those initial baryons. Neutrinos whip around way too quickly to help account for galaxy shapes.

The speed of expansion can be dialed out of current theories by changing a parameter that Einstein invented, called the cosmological constant, but the shapes of galaxies are tougher to explain.

Re:I don't get it

[Cyno]

Actually I'd probably conclude that my tools for measuring needed to be recalibrated. But I get your point. Personally I'd prefer to explain things with science that everyone can understand. When we talk about the Grand Unification Theory any religious nut, politician, or old person can't possibly understand what dark matter is. The very foundation of their system of beliefs would have to be broken for them to accept the possibility of alternate dimensions, etc. Personally I prefer to believe that its all theory until we have some hard cold facts, and attempt to build an hypothesis based on things that have been proven to exist. But that's just me, and I admit I'm weird. :)

Re:I don't get it

[Eccles]

What's next for our divine intellectuals to discover? Moons around those planets? No, say it ain't so.. Did we take into consideration the mass those moons have and their effect on the Stars, when determining how much dark matter exists?

At least in the only solar system for which we have particularly accurate measurements, the mass of the planets, moons, and assorted detritus is less than 1% of the mass of the sun. So it's unlikely that objects of those types will make up much of the mass of the galaxy.

Re:I don't get it

[Anonymous Coward]

Okay, classify the types of known possible planets, with cooking instructions.

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

Re:I don't get it

[pclminion]

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.

I believe the equation you are referring to is:

E = m*c^2/sqrt(1-v^2/c^2).

If v > c, then (1-v^2/c^2) < 0 and the denominator becomes imaginary. Thus in order for the particle to have real energy it must have imaginary mass.

I think imaginary mass is even harder to envision than negative mass.

Re:I don't get it

[p3d0]

Well, when their "theories" predict things better than traditional "facts" then I'm prepared to listen.

(Oh, and do you believe that these scientists are such knuckle-dragging dimwits that they wouldn't double-check their equipment, and also have other researchers independently verify their results on different equipment, and then scrutinize their conclusions? You seem to think they're a bunch of individual clowns with no common sense jumping to wild conclusions. But that's just my opinion.)

Re:I don't get it

[Cyno]

But what happens if we prove these theories to be true? How can we explain to the world that the Universe exists in 11 or 24 dimensions? It contradicts the founding beliefs of most bodies of power. Not that the Universe is extradimensional, but that it is more than what we percieve as reality. How do we create laws for such a land. See what I'm getting at? If science can no longer conform to what society believes to be reality, which is classified as sanity, then society must conform to science. However society does not want to conform and it holds all the keys that unlock science, like money and power. What good is it to know the secrets of the universe when you won't ever be able to tell your parents or grandparents?

Re:I don't get it

[Cyno]

Ooo, I like that :)

I can't even imagine how much imaginary mass I'd have flying 300,000,001 m/s through space. Probably not very much.

Re:I don't get it

[The Only Druid]

Its hard [to imagine imaginary mass] only because of a nominative problem. "Imaginary" only means that the mass occupies a perpendicular dimension. While its not _easy_, you could conceive of mass occupying alternate dimensions (this would, of course, blur into the other categories I already described).

Re:I don't get it

[p3d0]

All interesting questions.

What good is it to know the secrets of the universe when you won't ever be able to tell your parents or grandparents?

Well, if you can make more accurate predictions, and create new useful devices, that must come as some consolation.

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.

Re:Not Dark matter

[Anonymous Coward]

actually you got it wrong...here is what it said at everything2.com

There are currently two theories for what dark matter is. The first is the MACHO theory. MACHO stands for Massive Compact Halo Object. This basically means there are large objects orbit on the outskirts of the milky way. These are large objects which weren't big enough to become stars. They are probably about the mass of Jupiter. We know that at least some MACHO's exist by the way they lense or bend the light from a distant star. Although we have observed lensing, it doesn't occur frequently enough to account for all the mass that needs to be in the outer halo.

The other dark matter theory is for WIMPS. A WIMP is a Weakly Interacting Massive Particle. In this case massive means massive on an atomic scale. These particles have a tendency to not interact with other particles. They also cannot radiate away energy. Because of this they can't lose energy easily and orbit at great distances. This would explain the extra mass needed to sustain the rotation of galaxies.

It will be a long time before we have conclusive evidence as to what dark matter is and whether or not it exists.

the first one about MACHOs basicly the theory was that these big objects "around the edge of the galaxy" caused the faster spin...well if you have stars out there it sort of removes the need for machos...anyway i don't know if this accounts for all the dark matter (1%, a mass of 1 billion suns) but it is a good start.

Re:Not Dark matter

[prizzznecious]

Extra mass on the rim alone could not account for the mass discrepancy, but what you're missing is that if scientists couldn't see these stars until now, who knows what else they're missing?

I mean, these are light-emitting stars, even. What about brown dwarf protostars and even dark clouds of space dust?

The observation that stars at the edge of our galaxy don't move fast enough shouldn't incite scientists to come up with new types of matter--it should incite them to find the matter that they've obviously overlooked.

Re:Not Dark matter

[Hayzeus]

The observation that stars at the edge of our galaxy don't move fast enough shouldn't incite scientists to come up with new types of matter--it should incite them to find the matter that they've obviously overlooked.

But is "dark matter" really supposed to be a new type of matter? I understood that it was just extra mass we couldn't see. But then IANAA (obviously). Cheers --

Re:Not Dark matter

[Anonymous Coward]

Extra mass on the rim alone could not account for the mass discrepancy,

Then what about the MOCHO theory?

but the rest you got right...1% does not account for all the dark matter (i presume) but if you add in nutrinos and the new stars it fills in the gaps...i would not be suprised at all if they found some more black holes out there and some more space dust etc

hook

Re:Not Dark matter

[jbischof]

True, it does seem like dark matter is a open invitation for everyone to invent whatever they want when they should really be looking harder for normal stuff.

I guess I was a little hasty with my judgement that they aren't the missing dark matter. They could be part of the problem, a little chunk off of the grand total of missing mass that we have.

Re:Not Dark matter

[kevlar]

MACHO's are and always have been a scientific excuse for the "missing" matter. I say "missing" (with quotes) because what scientists consider "missing" is simply matter that they cannot SEE versus matter they cannot detect. They CAN detect it indirectly though, which is the fundamental reason they fabricate the need for WIMP's and MACHO's. Meanwhile, a simple solution to this "missing" (or what they really should call "unseen") mass is trillions of massive objects on the planetary scale which are not large enough to produce fusion, and therefore VERY hard to see, but are abundant enough to influence the galaxy's rotation. In essence, MACHO's are an exotic excuse to something lots of astronomers refuse to admit: there's a lot more unseen barionic matter out there.

As a mathematical model, MACHO's are great. In reality though, they're simply barionic matter that we can't see, not some exotic particle. The simple explaination is that there are butt loads (Butt, n: any of various units of liquid capacity; especially : a measure equal to 108 imperial gallons, 491 liters)of planets the size of Jupiter surfing the galaxy.

Re:Not Dark matter

[Anonymous Coward]

...because the entirety of the content on everything2 has been properly vetted and should be taken as the infallible word of god.

Personally, I prefer the 'appeal to google' fallacy which covers the "I found something that agreed with my position when I typed it into google, so it must be true!"

Re:Not Dark matter

[jbischof]

Okay, my comment "Extra mass on the outer fringe of a galaxy could not contribute to this lack of gravity" is wrong.

There is very little information out there on how far out this "Halo" needs to be, or how massive, or how far out our ring of stars is comparitavely.

MACHO's are Halo objects around the galaxy, but they are suspected to be much more massive than normal stars. Black holes and brown dwarfs making up much of the Halo would help. Regardless, the amount of mass measured does not end our search for dark matter.

hmmmm

[CySurflex]

At first I read: "Scientists have found Ringo Star around our galaxy"

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.

Re:hmmmm

[kin_korn_karn]

yeah, but he was still a step above Pete Best. ever hear the Anthology 1 stuff he played on? damn, he sucked.

No, no dark matter.

[foolip]

The article is /.ed, so I can't read it. Sorry for any grave mistakes. Could this be part of the elusive 'dark matter' talked about so much lately?

No, don't think so. As I understand it (and I know nothing really, I'm in the gymnasium), dark matter is neither matter or antimatter. Rather, dark matter is a hypothetical something which has been thought up to account for some otherwise unexplainable phenomena.

This simply seems to be concerned with our technology becoming more accurate and hence being able to record previously invisible things -- such as faint stars around our galaxy.

Re:No, no dark matter.

[mathin]

There is also a story at New Scientist, if you can't read this one.

Re:No, no dark matter.

[Randolpho]

Space.com slashdotted? That'll be the day.

Hmmm...

[CommieLib]

Maybe the ring makes them invisible? Maybe it binds them all? Maybe it...oh, never mind.

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.

Re:Space and Science can explain anything...

[Guppy06]

What about the stars you saw revolving around your head as soon as those words crossed your lips?

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.

Could this be part of the elusive 'dark matter'

[matt4077]

Could this be part of the elusive 'dark matter' talked about so much lately? No. Stupid Question. Go to jail. To not pass go. Do not collect 400$

i am 8 years old

[circletimessquare]

so if there are rings of dark matter and large clouds of gas around uranus, i mean uh the milky way... how do you wipe out the klingons?

Re:i am 8 years old

[littleRedFriend]

Better question yet, at which star system shall we start the third foundation? Harry Seldon would have been excited!

I've heard...

[Anonymous Coward]

They've discovered rings around Uranus. Lots of dark matter too!

"There's Klingon's on the starboard bow, starboard bow, starboard bow..."

Re:I've heard...

[Anonymous Coward]

Ewwwwwwwww! I just don't want to know!

Re:I've heard...

[Anonymous Coward]

Scrape 'em off, Jim...

Spelling troll

[Anonymous Coward]

To not pass go. Do not collect 400$

Spelling mistake! Go to jail, do not pass go, collect a ANAL WOUND!

What if it's the other way around?

[core plexus]

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?

Man Gets 70mpg in Homemade Car-Made from a Mainframe Computer

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:What if it's the other way around?

[Anonymous Coward]

seeing the Milky Way cannibalizing a small galaxy and incorporating it into the galactic disk..."

When was the last time a smaller galaxy got to cannibalize anything?

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

[pseudochaotic]

This isn't a SOVIET RUSSIA joke, is it?

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

[core plexus]

No, they collapsed without any ring of stars to influence them.

But it sure could be.

Bring It on.

[Anonymous Coward]

All Amateur Physics and Astronomers please post stupid comments that state nerdy comments that point out funny or humerous *space jokes*. That no one else other than you and your polyester pant wearing friends will get.

Also making fun of the article posters obvious ignorance is highly encouraged.

Thank You. Please continue on with your pointless boring lives.

Where does the galaxy end?

[teamhasnoi]

If we keep looking for stars, our galaxy will end up as big as the universe.

Besides, everyone knows that the 'dark matter' is really a black hole caught in the center of the earth, holding all of us (even upside-down China) with its massive gravity particles. Duh!

Your pal,

Stephen Hawking

This Just In ...

[handy_vandal]

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

Re:This Just In ...

[smnolde]

"My God! It's full of stars!"

Re:This Just In ...

[Anonymous Coward]

Actually, with a 95% certainty, it is between "really big" and "really, really, really big"

Re:This Just In ...

[glenebob]

It is also vastly hugely mind-bogglingley big.

Re:This Just In ...

[squireofgothos]

The management would like to apologize and offer a correction to the previou news cast: It seems we left out a few "really"s...

Re:This Just In ...

[m1chael]

in respect to what? if there are an infinite number of parallel universes then they have to be really small...

Re:That's nothing..

[Anonymous Coward]

Yeah, that is some serious dark matter right there.

no way

[Anonymous Coward]

there is no way that previously unknown matter could be part of the dark matter.

Amazing: +1, Informative

[Anonymous Coward]

a self-referencing critic

Re:Not Dark matter QWZX

[Anonymous Coward]

so rather than think our theories might be wrong we invent dark matter.

Wrong, troll.

Because the real world does not fit our theories, then we invent other theories to attempt to fit the facts. One of these theories is that there may be "dark matter" that is difficult to detect.

Of course, there are other, competing theories to explain the discrepencies as well.

In other words, everyone knows that something is wrong with the current theories. The question is what needs to change in the current theories to fit the facts.

Re:Not Dark matter QWZX

[Anonymous Coward]

Heh heh. You're right. The troll you are responding to doesn't seem to understand how things work.

I am hypothesizing something called "dark stupid" to explain what's inside his head.

obduh!

[Thud457]

Obligatory Niven (consider yourself warned):

...one ring to orbit them all and in the darkness bind them....

ob Red 'Lectoid

[Thud457]

Where are we going?

Planet X!

When are we going?

Real soon!

I am 8 years old continued

[Zeebs]

If uranus is the milky way try some bran.

Re:I am 8 years old continued

[circletimessquare]

HAHAHAHAHA ;-)

These stars aren't dark matter....

[Anonymous Coward]

They are the slightly less discussed "darkish matter"

Not really full of stars ...

[handy_vandal]

... more like it's littered with stars.

Re:Not really full of stars ...

[Anonymous Coward]

Yeh, them stars are real blight upon the perfect chaos of deep space. Atleast they usually clump together and can easily be steered around. Who'd ever think bumping a couple of universes together would creat such havoc.

How Really is Really?

[handy_vandal]

We need a new unit of "really big" ... the "mega-really" ... or better yet, the "way really".

Dark Matter is really...

[SoVi3t]

Dark matter is really God.... *end religious post*

Re:Dark Matter is really...

[Anonymous Coward]

Thats correct. Things we do not (yet) understand is often referred to as "God".

detergent

[Guipo]

New Tide laundry detergent even cleans the ring around the galaxy!

Matter, Matter everywhere

[ackthpt]

Grey Matter

Matter Horn

Another Matter Entirely

Alma Matter

Whatsa Matter You

Matter 'n a Wet Hen

Anti Matter

Auntie Matter

Anti Auntie Matter

Auntie Anti Matter

Mindover Matter

Matter of Time

Matter of Fact

Matter of Fiction

Matter of Process

Laughing Matter

No Laughing Matter (also known as: Anti Laughing Matter)

Private Matter

Public Matter

And the aptly named Sir Matter not appearing in this list

Personally, I think they forgot to dust the lens.

oh, I know what it is

[Tablizer]

Damned Warchalkers

Armchair physics.

[eadint]

ignore my spelling.
if you thought of a baloon, being inflated in the center wouldnt the particles on the outside be the oldest relative to the gas entry. so i would think that the stars on the outermost edge would be the oldest, according to this article it is the opposite. why?
i no nothing of physics. other than what they taght me in college.

more data needed

[1fitz2many]

I didn't notice any mention of velocity data from the article, or what method was used to determine distance. This would be important in understanding the ring's history.

However, one could speculate that if these stars are indeed part of a ring, the ring may have formed through a collision with another galaxy. For an example, check this out. Here is another example of a ring galaxy.

I'm special!

[Orthogonal Jones]

**My** galaxy is an anomaly? Wow, I feel so special!

Milky Way kickin' it old-star-school style! Milky Way in da house!

Need to cut down on beer...

[ATAMAH]

...cause i read the name of the article as:
"Ringo Star found around Milky Way" :)

Big Bang Nucleosynthesis

[lythari]

Baryonic matter cannot account for dark matter because of big bang nucleosynthesis (BBN). BBN gives us a fairly accurate esimation of the baryonic matter density of the universe. The result derived from BBN agrees with the mean mass density obtained by summing the visible matter from a representative sample of galaxies. Thus this suggests that dark matter is non-baryonic.

Not the Dark Matter.

[Axe]

Distribution of the Dark Matter must be heavily cusped in the middle of the galaxy to account to the observed rotational curves. It can not be explained by far away objects.
The second problem is that there must be a LOT of DM.. Not a few faint stars..

Re:Not the Dark Matter.

[955301]

So what do you think about the hypothesis that dark matter is the matter in an adjacent universe who's properties cause side affects in our own. This would imply that gravity is not constrained to one space-time, but also affects those universes around our own.

I can't help but think something like this, in combination with the theory that black holes in one universe are the points of origin for adjacent universes. I've heard it said before that most galaxies have a black hole at the center at the least?

That might account for both of your points, along with the observation that the universe is constantly expanding (matter continuously arriving through the black hole in another universe).

Re:Not the Dark Matter.

[Axe]

Among the current theories that are more "exotic" then WIMPs (neutralino and friends) those that deal with the breakdown of the Newton law at large distances look like the most promising..
Many people do not realise that general relativity equation do have some fairly heavy assumptions - like requirement for the equations to be of no higher then second order. It may be possible to write a different theory that will lead to non-linear beahviour of acceleration for small forces. That would explain rotational curves (the most solid evidence for dark matter) without dark matter.
Nevertheless, WIMPs involve less new assumptions, at elast at this moment, so Brother Occam tells us it must be true.. ;)

The Milky Way is a Barred Spiral

[Anonymous Coward]

For a long time, I've heard that some astronomers think the Milky Way is a barred spiral galaxy. It's of course very hard to tell looking out from within. This discovery would tend to vindicate that view. What they have detected is the ring of stars that form the faint spiral around the outer periphery. We live at the far end of one of the bars. Have a look at this photo of NGC5850 and you can see what I'm talking about. It's "ring" is a bit more prominent than ours though. Google has more.

Re:That's nothing..

[Anonymous Coward]

It's a veritable black hole.

That explains it.

[g4dget]

Astronomers have discovered portions of what appears to be a giant, donut-shaped ring of previously unseen and surprisingly old stars surrounding our Milky Way Galaxy.

Wow, that explains why he made the international sign of the donut.

probably not

[rebelcool]

MACHOs are enormous objects like supermassive blackholes. There arent many of them, if they actually exist.

The reason there can't be many of them is we'd probably have detected them already by gravitational lensing. So whatever it is thats out there, its really heavy, and theres not many of them because so far we havent seen any lensing from objects near the edge of the galaxy.

In order to make up the necessary 'missing matter' from things like faint stars, neutron stars or dead stars, there would need to be alot of them.

While we're on theoretics, its also possible the phenomenon is related to dark energy, which has recently (within the past couple months) been nearly proven to exist by studying several lensing objects. 'Dark Energy' is likely whats responsible for the increasing rate of expansion in the universe. Its effectively a kind of anti-gravity. Its nature, such as where it comes from, is still totally unknown.

Is it just me....

[blind_abraxas]

...or do mass of the universe calculations meant to encompass everything done by people who can't detect everything seem like a huge waste of resources that could be better spent building me a hot dog and fry stand on Venus or Mars?

Re:Is it just me....

[JoeRobe]

I don't think it's a huge waste of resources. We can approximate the mass of the universe by looking at rotation curves of galaxies, luminous matter, etc. It is precisely the fact that we can't see some of this mass which we know exists that makes the dark matter problem so interesting. We can detect it - that's easy - just look at rotation curves. The fact that we can't see it doesn't mean we can't detect it...

LOTR?

[bogado]

This gives a hole new dimension to lorg of the ring. :-)

And now she won't return my calls.

[Anonymous Coward]

You know, I said the *exact* same thing to a date last night.

Only?

[Anonymous Coward]

Only accounts for 1% of the galaxies mass? Dude! That's one out of every 100 stars! That would definitely make a big dent in your average theoretical physics calculations.

This really seems to be common sense...

[Zenjive]

admittedly, I hadn't thought of it until seeing this article.

We keep finding new moons around our gas giants, new planets further out in our solar system, so why shouldn't there be stray stars out beyond the "perimeter" of our galaxy (or others for that matter).

I suppose the "dark matter" speculation is that there are possibly many stars floating around between galaxies, too small and far away to be visible... all alone, with no massive gravity wells to keep them company. sigh ...so sad

In Soviet Russia...

[Slur]

...Dark Matter detects YOU!

Could this be part of the elusive 'dark matter'..?

[Anonymous Coward]

Yes. Anytime you find unseen matter, it falls under the category of elusive dark matter.

I only got so far

[Anonymous Coward]

Mmm... donut.

This COULD account for dark matter:

[Anonymous Coward]

Quoted from From Everything.com:

There are currently two theories for what dark matter is. The first is the MACHO theory. MACHO stands for Massive Compact Halo Object. This basically means there are large objects orbit on the outskirts of the milky way. These are large objects which weren't big enough to become stars. They are probably about the mass of Jupiter. We know that at least some MACHO's exist by the way they lense or bend the light from a distant star. Although we have observed lensing, it doesn't occur frequently enough to account for all the mass that needs to be in the outer halo.

Now say only a small percentage of that halo is actually stars, the rest could be those MACHO's.

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.

CraigParticle!

[Anonymous Coward]

Everybody listen to CraigParticle. He's an astronomer, and is right on the money. (Even if he forgot a closing tag. :)

Now, CraigParticle, do you remember this?

Smeared across the floor
My last thought before passing
I must kill Kevin

:)

Good luck,
The guy across the hall in the Dome for a year, who is at Cornell now.

Re:CraigParticle!

[CraigParticle]

Dude! :) Ahhh, quake haikus. A fine, fine pasttime.
Waitaminnit. Cornell still? Aren't you done yet? [ducking] ;)

Now if you'll excuse me, I have to go stand in a corner and write on the chalkboard a thousand times:
I will preview my posts before submitting them.
I will preview my posts before submitting them.
I will preview my posts before submitting them .
I will preview my posts before submitting them.
...

Dangit.

Oh great

[chris411]

Now we have seven days to live! Thanks a lot scientists!

Not surprising

[Anonymous Coward]

While I am no astronomer, I do not find it surprising. Any analogy with The Solar system itself, or, Saturn, Jupiter etc. is too immediate. It seems like the same event but on a larger scale.

Speculation

[cardshark2001]

Speculation is at least reasonable in an area of astrophysics where the practicioners themselves will gladly admit to anyone who won't tell them to shut up because no one likes to talk about his job. This is my opinion, at least.

I have an idea that I've never really read anywhere, and I've always wondered why. What if gravity is a source of both attraction and repulsion, but the attraction affect is much stronger within a certain locus, such as within a galaxy? Now, take that idea and imagine a sort of fractal effect, leading to clusters of galaxies, and clusters of clusters.

So the affect that pushes galaxies away from each other is also gravity, but Newton's law gets bent over intergalactic distances.

I'm stepping all over everyone's toes here, because I've had only basic physics coursework, so I apologize now to any astrophysicists I might have offended.

The MOND theory: Alternative to Dark Matter

[Erioll]

In the August 2002 edition of Scientific American, an alternative to Dark Matter is explored in the cover article. This alternative, called Modified Newtonian Dynamics (MOND), basically (VERY basically) proposes that F != ma, and that there is a very slight exponential component to the curve at extremely low accellerations, such as is experienced by large galaxies interacting. At more "traditional" accelerations, the curves become virtually identical, and MOND behaves almost exactly like the classical equation governing motion.

A gateway to some knowledge about this topic is at The MOND Pages . I'm sure if people search around, they can find better sources, but it remains an interesting topic to discuss in relation to the "missing matter" problem. If this pans out, then maybe not much is really missing at all. Or maybe a lot is. Only time will tell which theory is correct.

Erioll

Not Actually Tolkien Ring

[Ilan Volow]

Technically it's a star topology.

More information.

[GGLoPingHo]

I am really interested in all the astronomy and physics stuff out there. I would really love it if you guys had any really cool sites about these kinds of things you could send me. I would really appreciate it.

hoo haa

[Anonymous Coward]

In other news a scientist is quoted as finding Klingons circling Uranus.

-t

Those are not stars!

[Snaller]

It's the barrier around the galaxy! StarTrek was right all these years!

Missing matter

[Anonymous Coward]

About 80% of all matter in the universe is missing.
They just found 1% more matter in our galaxy.
There are many billion galaxies in the universe.
You do the math.

Ten Thousand Things

[handy_vandal]

Maybe an infinite number of parallel universes are not small but crowded?

"From the One come the Two
From the Two come the Many
From the Many come the Ten Thousand Things"
- Lao Tzu

"Yeah, and then you have to find some place to put them."
- Paul Busch

Evidence of Dark Matter Halo?

[yelmalio]

We know Spiral Galaxies are embedded in Dark Matter. This is pure speculatipon but could this ring be evidence for the outer edge of the Halo?

Spiral structure is thought to be due to Lin-shu density waves. It's a given they only extend as far the Galaxies visible structure. For the sake of argument the denser dark matter thought to be responsible for triggering collapse and thence galaxy formation may have had a larger radius than the spiral density wave. Note that early galaxies often are chaotic or flocculent. Could these be stars formed at the edge of the early Milky Way's extent before spiral structure was imposed.

Alternatively, is this just a dim afterglow of a collision in the past. Something like a ring Galaxy?

Warning - Cretinist reference

[kelddath]

Yep, had to arrive sometime I suppose - the above link is nowt but a creationist hodgepodge of crapola which claims that the speed of light has conveniently decayed enough for the universe to be, wait, 6,000 years old.

Never mind that 1) observed supernova light curves at cosmological distances uttery disprove this 2) the creationists own calculatations myseriously "ignore" a whole host of data which disproves their hypothesis and 3) their calculations would lead to the Earth being a radioactive slag-heap not 4,000 years ago.

So take the above link with a massive truckload of your favourite saline product.

Best,
Kelddath

Re:Warning - Cretinist reference

[zmooc]

Could you please post some links for your arguments? The only arguments against the CDK-theory I've found so far are on the same level as yours; incomplete. I'm very willing to believe the oppossite, but so far haven't found any theory that proves CDK wrong with good arguments. How do supernova light curves (what are they?) prove CDK wrong? As far as I know, the calculations were based on statistical evidence which therefore do "ignore" a lot of data but all data points in that direction and most certainly does not prove CDK wrong. How would their calculations lead to earth being something it clearly was not [4K yrs ago]?

Apart from that, the CDK theory potentially solves a lot of problems and mysteries about dark matter and the expansion of the universe.

Dark Matter and microlensing.

[Christopher Thomas]

...wait. Isn't dark matter supposed to still have mass and gravity? So any dark matter of sufficient size would cause microlensing, not just baryons, no?

Only if it's concentrated into very compact clumps.

If it's a halo of low-mass chargeless particles, clumps would be much larger (think "galaxy-sized or bigger"). Such dark matter would not be directly visible within our galaxy, though "dark galaxies" or larger blobs of dark matter could be seen by lensing of distant quasars. Searches for "dark galaxies" have been underway for a while (though the main purpose is to look for ordinary galaxies that are just dim enough not to be seen that far away, if I understand correctly).

Things like "dark energy" might not clump at all (I'd have to look that up to confirm it, though).