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Space Science

The Starry Sky Just Got Starrier 186

Posted by samzenpus
from the twinkle-twinkle dept.
An anonymous reader writes "Astronomers have surveyed eight elliptical galaxies, and found that we've vastly underestimated the number of dim red dwarf stars in these giant galaxies. When they used the new number of red dwarfs in their calculations, they tripled the total number of known stars in the universe."
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The Starry Sky Just Got Starrier

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  • first? or third? (Score:3, Interesting)

    by mug funky (910186) on Wednesday December 01, 2010 @07:08PM (#34411610)

    dark matter much?

    • by Fluffeh (1273756)

      dark matter much?

      Apparently less :)

    • Re:first? or third? (Score:4, Interesting)

      by Nugoo (1794744) on Wednesday December 01, 2010 @07:11PM (#34411654)
      To phrase that as a real question: What effect does this discovery have on the current estimates of the amount of dark matter in the universe?
      • Of course working on the assumption that Dark Matter even exists. Unless I am mistaken there is no actual direct evidence to its existence and it is used mostly to explain phenomena not fully understood. It may be the modern equivalent of luminiferous ether and disproved in the future.
        • by Urkki (668283)

          Of course working on the assumption that Dark Matter even exists. Unless I am mistaken there is no actual direct evidence to its existence and it is used mostly to explain phenomena not fully understood. It may be the modern equivalent of luminiferous ether and disproved in the future.

          Well, there's the classic Bullet Cluster [wikipedia.org]. There's something that bends light but is otherwise completely invisible. It's not necessarily dark matter, but other explanations sound even more far-fetched.

      • by radtea (464814)

        effect does this discovery have on the current estimates of the amount of dark matter in the universe?

        The what?

        The term "dark matter" on its own, unless you an scientist using it in a specific context, is not meaningful. When a layperson uses it as you have it is meaningless.

        You have to specify which dark matter you mean. There is "missing matter" at all distance scales above some relatively modest threshold, but there are quite different constraints on what it might be depending on the scale you're observing.

        When anti-scientific nutjobs on /. bitch out the purported arrogance of scientists who postulate "

    • by spun (1352)

      Good question. Assuming you are asking something along the lines of "How does this finding effect the ratio of dark to regular matter?" My guess is, not much, because I don't think the ratio ever really depended on observations of stars, per se.

      • by Hatta (162192) on Wednesday December 01, 2010 @07:17PM (#34411720) Journal

        Really? I thought that they used gravity to determine the approximate mass of the galaxy, and then subtracted the amount of visible matter to yield the amount of dark matter. If that's how they did it, then increasing the amount of visible matter would have to decrease the amount of dark matter.

        • by arth1 (260657)

          Minor corrections:
          - Not only the visual spectrum, but the entire electromagnetic spectrum.
          - Black holes are also added to the baryonic matter count, and their masses are estimated based on their effect on observable matter. For faraway objects, one can assume that the number and sizes of black holes compared to visible matter is lower than the ratio in our neighbourhood, simply because faraway galaxies are much younger, giving black holes less time to appear and grow.

          Anyhow, I see this as good news for our

        • Re:first? or third? (Score:4, Informative)

          by John Hasler (414242) on Wednesday December 01, 2010 @07:29PM (#34411864) Homepage

          They don't determine the mass of a galaxy by counting stars.

        • by Bigjeff5 (1143585)

          You are correct, but the amount of dark matter figured in this way was roughly four times the amount of visible matter. A full tripling of visible matter (which is not what happened - these are teeny tiny stars, which is why they were missed before) would only set dark and visible matter roughly equal to each other.

        • FTFA:

          Elliptical galaxies posed a problem: The motions of the stars they contained implied that they had more mass than one would get by adding the mass of the normal matter astronomers observed to the expected amount of dark matter in the neighborhood. Some suggested that the ellipticals somehow had extra dark matter associated with them. Instead, the newly detected red dwarfs could account for the difference, van Dokkum says.

          So this doesn't really decrease the amount of dark matter in the universe. It simply shores up the anomalous hypothesized excess of dark matter observed for elliptical galaxies in comparison with spirals.

      • Good question. Assuming you are asking something along the lines of "How does this finding effect the ratio of dark to regular matter?" My guess is, not much, because I don't think the ratio ever really depended on observations of stars, per se.

        What was the need for there to be dark matter in the first place? Wasn't it invented as a concept to explain why the universe is the way it is assuming it has a specific amount of stars in it? Has anyone proven that dark matter exists or is it just a convenient kludge to make a model of the universe fit observations?

        If they discovered that there are 3 times as many stars as previously believed then what purpose does the concept of dark matter serve?

        • by abigor (540274)

          Non-baryonic dark matter has to exist in order for certain observations made on the cosmic background radiation to make sense. Basically, the Big Bang couldn't have happened without it. There's a lot more to it than just missing mass.

          As for evidence, there's enough to infer it exists, but its exact composition remains elusive, so far as I know with my layman's understanding of this stuff.

          • by lgw (121541)

            The best evidence is that, by observing galaxy rotations, it seemed like the galaxies needed to be about 80% dark matter for the rotations to make sense (there were several competing theories at that point). Then the CMBR observations pegged the composition of the universe at that early time at about 80% dark matter. The unrealted theories agreed to a couple of significant digits, which pretty much settled the matter (as much as anything in cosmology can ever be known).

            • by Fluffeh (1273756)
              I explained the need for Dark Matter previously here on /. [slashdot.org] and folks seemed to like the explanation so I am reposting:

              It is something more along the lines of this: We have a good number of formulas and calculations that work properly with the things we can measure - planets, the sun, cars, planes, kitchen scales. One of these might be:
              y + 3 = 5
              Nice and simple for this example. Lets say that the "y" here represents gravity and the formula has been proven in every experiment we have done.
              We therefore as
              • So why was it wrong for Einstein to add Cosmological Fudge Factor X to the equation, but not for us? How do we know, or what makes us think, that the missing matter is non-baryonic in nature?

                • by Fluffeh (1273756)
                  It wasn't wrong for Einstein to add it to the math - it just ended up unneeded. It is simply a way to make what we know work, when we are clearly missing something. You can do a lot with an equation that works even if you can't understand all of the details in it - just ask most math students during an exam. They might know how to get the right answer, but not be able to explain why it is the right answer. Same thing here really.

                  The reason we think think it is non-baryonic is because we simply haven't fo
          • by fyngyrz (762201)

            Basically, the Big Bang couldn't have happened without it.

            Well, considering that nothing in our physics confirms that the big bang even COULD have happened, I'm pretty comfortable with not assuming invisible things exist to back up an hypothesis that isn't possible under normal physics anyway. The big bang is just hand-waving at this point in time.

            Ascribing it the status of certainty is the result of not consuming the available objective facts, in particular that the states described for the importan

            • by Chris Burke (6130) on Wednesday December 01, 2010 @10:24PM (#34413160) Homepage

              The big bang is just hand-waving at this point in time.

              Hand-waving, one of the most successfully predictive theories [xkcd.com] of the last century, these are both the same. I'll make them seem like they're both the same by... wait for it... waving my hands.

              • one of the most successfully predictive theories of the last century

                [rollseyes] Oh, please. Horizon problem? Doppler problem? CMBR problem (well, two of them, really)? Anti-matter problem? Dark matter / energy fudge factor / problems? Large scale void problem? Speaking of fudge, inflation? Really? Distant young galaxy problem? And the really big one, the singularity: BB theory doesn't actually oblige us by conforming to what we know about physics. It's just a math model, and it looks a good deal more l

        • by Albinoman (584294)
          True, Dark Matter, like Dark Energy, is just a placeholder name for something that we know is there. What we're seeing is patches of gravity where none should exist. Even with all those red dwarfs being added it still doesn't come close to making up for all the extra gravity. I heard Neil deGrasse Tyson say at a lecture (which certainly could be outdated) that observable mass accounts for about %5 of of all the stuff out there.
          • Re:first? or third? (Score:5, Interesting)

            by UnknownSoldier (67820) on Wednesday December 01, 2010 @07:50PM (#34412030)

            > True, Dark Matter, like Dark Energy, is just a placeholder name for something that we _think_ is there.

            FTFY.

            Probably will get modded down, but if you "knew" it, then you would be able to prove it exists. Since no one has seen it, touched it, tasted it, smelt it, or felt it, therefore it is a mathematical kludge, aka, the aether of the 1900s. (Yes, I'm aware of http://www.nasa.gov/home/hqnews/2006/aug/HQ_06297_CHANDRA_Dark_Matter.html [nasa.gov] )

            Ergo, while said more politely, "it falls out of the math", which will allthough appear quite reasonable at first, given the current limitations of understanding gravity / light / mass & energy, it is still one a big hack-job based on one assumption after another, namely:
              a) that there is only one type of gravity and
              b) gravity is universal (which is a little preposterous / pretentious to base how the WHOLE universe works based on one tiny little planet.)
              c) redshift is accurate (ARP has interesting evidence that calls into question this assumption)

            This prof. provides a half-decent summary though:
            http://zebu.uoregon.edu/1999/ph123/lec08.html [uoregon.edu]

            • by geekoid (135745) <dadinportland&yahoo,com> on Wednesday December 01, 2010 @08:03PM (#34412138) Homepage Journal

              Since they can make predictions with it, and have tons a data supporting there is an effect going on, you're wrong.

              "Since no one has seen it, touched it, tasted it, smelt it, or felt it."

              the same can be said for gravity.

              Now if you added 'measured it' then it couldn't be said for gravity. Of course then it couldn't be said for dark energy and dark matter.

              a) There is no evidence of any other kind. Should some good evidence actually come in, then great.

              b) Every measurement we have made using our understanding of gravity seems consistent. Again, if there is actual evidence of something else, then thing will change.

              c) interesting evidences doesn't matter, strong* evidence does.

              Your post shows a large amount of ignorance on this matter, and ignorance on the scientific process.

              *no pun intended.

              • by Nemyst (1383049)
                Sorry, but the Ptolemaic system was, back in ancient times, a very accurate representation of planetary movements. From your first line, then, Galileo would be wrong.

                There always needs to be a sufficient amount of skepticism to everything we devise. Dark matter really is aether. We don't know what it is, we can't observe it so far, the only thing we know is the effects it does. However, interesting theories (such as Hoava–Lifshitz gravity [wikipedia.org]) have sprung up that try to explain the effects we see withou
              • "Since no one has seen it, touched it, tasted it, smelt it, or felt it."

                the same can be said for gravity.

                Really? Where do you live? I feel gravity constantly.

              • > Since they can make predictions with it, and have tons a data supporting there is an effect going on, you're wrong.

                Um, no.

                http://www.newscientist.com/article/dn13280 [newscientist.com]

            • Re:first? or third? (Score:5, Informative)

              by spun (1352) <loverevolutionar ... m ['hoo' in gap]> on Wednesday December 01, 2010 @08:04PM (#34412142) Journal

              No, it's out there. Things like the bullet cluster pretty much prove that there must be large amounts of some sort of weakly interacting matter. Basically, two galaxies collide. Normal matter in one galaxy interacts with normal mater in the other, slowing it down. But something massive wasn't slowed down and kept right on trucking along the same path at the same speed as before. We only know it is there because of the gravitational lensing it produces. So, we have direct evidence of matter that we can not see, and that does not interact with other stuff except through gravity. Call it whatever you like, it's out there. And that is just one piece of evidence. Galaxy rotation and the CMB are others.

              • by Nutria (679911)

                Call it whatever you like

                How about "really dim baryonic matter". After all, we're Really, Really Far Away.

                • by spun (1352)

                  Really dim baryonic matter would only explain some of the many different lines of evidence.

                  I don't really have a horse in this race, I mean, I could care less which theory turns out to be correct. It just seems like the preponderance of evidence points to a non-baryonic source of mass at this point.

                  • I don't really have a horse in this race, I mean, I could care less which theory turns out to be correct.

                    Me neither. But it really seems odd that so many Slashdotters are so rabidly against the idea of dark matter.

                    • Re: first? or third? (Score:4, Interesting)

                      by drinkypoo (153816) <martin.espinoza@gmail.com> on Wednesday December 01, 2010 @10:27PM (#34413172) Homepage Journal

                      Me neither. But it really seems odd that so many Slashdotters are so rabidly against the idea of dark matter.

                      The story of humanity is full of whole chapters which basically boil down to a bright spark being smothered by a bunch of ignorant fuckwads attached to their idea of how the world works. Every once in a great while the spark lands in a pile of tinder not in the furnace-equipped basement of a firetrap and something wonderful is born, but mostly people shun what they don't understand and it's their children or their children's children who are willing to incorporate it into their lives as an escape from the previous generation who doesn't "get it". This is why the technological singularity is the religion most appealing to the technological elite...

                    • by Kjella (173770)

                      The story of humanity is full of whole chapters which basically boil down to a bright spark being smothered by a bunch of ignorant fuckwads attached to their idea of how the world works. Every once in a great while the spark lands in a pile of tinder not in the furnace-equipped basement of a firetrap and something wonderful is born, but mostly people shun what they don't understand and it's their children or their children's children who are willing to incorporate it into their lives as an escape from the previous generation who doesn't "get it". This is why the technological singularity is the religion most appealing to the technological elite...

                      But perhaps just as much due to the ratio of crackpots to revolutionary scientific insight as the fuckwads. Ok, the world has sometimes been in a "burn them at the stake" mode but most of the time it's just lack of sufficiently compelling evidence. Extraordinary claims require extraordinary evidence, it's often reasonable to assume that you've simply done something wrong or ignored some parts that didn't make sense but still punt your pet theory anyway.

              • by ghostdoc (1235612)

                Or things like the Bullet Cluster prove that we don't understand gravity nearly as well as we think we do.

                Put simply: two things interact, but don't conform to our expectations of how they should interact. Therefore:
                1. Our expectations must be wrong.
                or
                2. There must be something we're not seeing about the interaction.

                Dark Matter is basically saying "2, because our expectations seem to pan out for other interactions"

                But then...Dark Energy...

                Put simply: two things interact at very long distances, but don't con

            • gravity is universal (which is a little preposterous / pretentious to base how the WHOLE universe works based on one tiny little planet.)

              It would be, except that our observations of the effects of gravity cover countless measurements over the entire observable universe.

        • by melikamp (631205)

          IANOP, but this galaxy is 90% dark matter is just another way of saying that the amount of matter visible to us as stars and interstellar gas is dreadfully insufficient to account for how this galaxy rotates, even if we generously account for very dim collapsed stars and stellar black holes, for as many of them as we think have appeared since the Big Bang. Either General Relativity is wrong on a galactic scale, or there is a crap-ton of matter hanging out there that does not produce, block, or reflect any

          • by fyngyrz (762201)

            or there is a crap-ton of matter hanging out there that does not produce, block, or reflect any light.

            ...or there is something blocking the light it is emitting from getting to us. Or... the universe isn't the kind of lumpy they assume it is (there may be another scale of lumpiness beyond where we can see it.) Or we've got the mass estimates wrong. Or there is another force we're not accounting for. Or the forces we know don't act the way we think they act over large scales (20:1, after all, isn't much

          • by delt0r (999393)
            Every alternative theory to dark matter explains *less* of the observations than dark matter does (typically only one thing ie galactic rotation, but not CMB or large scale structure). Like or love it, its the best theory that fits the data that we have. And despite the fact that its wasn't well like for a long time, a better theory just have not been put forward.
        • Re:first? or third? (Score:5, Interesting)

          by spun (1352) <loverevolutionar ... m ['hoo' in gap]> on Wednesday December 01, 2010 @07:54PM (#34412056) Journal

          I believe this [wikipedia.org] is one piece of very strong evidence for some sort of pervasive weakly interacting massive stuff. Two galaxies collide. The normal matter interacts with other normal matter and slows down, The "other stuff" does not interact, and keeps moving. We know it is there because it creates a gravitational lens. If the lensing were caused by any sort of matter that interacted with other matter, these lenses would not be located where they are.

          So the theory of Dark Matter is more than just "there is more stuff than we can see." We can see specific phenomenon that normal matter just can not produce.

          • Your incorrectly summarize your own cite.

            Two galaxies collide. The stars are slowed by gravity but mostly go on their way, the gasses collide and slow down while emitting X-rays, some other stuff does not interact and keeps moving.We know it is there because it creates a gravitational lens. That lens is detected in the same place as the visible stars but has no observable light.

            Further from your cite

            Critics of dark matter have cautioned that astronomers expect sizable quantities of non-luminous baryon

            • by spun (1352)

              Sorry, got the bit wrong about the stars. But how could cold gas clouds not smash into each other? And why does this observation match up with so many others that also show the existence of dark matter? Critics like to take each piece of evidence separately, and cast doubt on each one, but they rarely seem to want to take on the whole package of evidence at once.

              • by fyngyrz (762201)

                The extra mass could simply be a much larger black hole in the incoming galaxy that had previously consumed most of it's surrounding matter. There's just too much that isn't known here to draw firm conclusions about anything.

                • by scotch (102596)
                  From what I've read, a large central mass (e.g. black hole) cannot account for the observed rotation. The mass needs to be spread throughout and even beyond the observable galaxy. I appreciate your question everything attitude, but I'm not impressed with what you know about the field to take you seriously.
                  • by fyngyrz (762201)

                    I'm not impressed with what you know about the field to take you seriously.

                    Sorry, I didn't realize anything significant depended on "impressing" you. Someone forgot to pass me the memo. Let me see, am I impressed by your post? No, looks like you didn't even understand what I said, so I guess... no worries. You just go right on with your unimpressed self, there. Isn't life fun?

          • by wvmarle (1070040)

            So this "other stuff" is there, does not interact with itself, but does interact with OTHER matter (light in this case) to create a gravity lens?

            I may miss something but to me it seems to contradict. How can its gravity interact with light, but not with itself or the non-dark matter in those colliding galaxies? If it produces that much gravity to create a gravitational lens, why doesn't it pull the rest of the galaxy with it?

            Dark matter interacts or it doesn't. It holds galaxies together, creates gravitat

    • Re: (Score:2, Informative)

      by Bigjeff5 (1143585)

      It won't boost as much as you think. It increases the number of stars, but red dwarfs are small and not very massive. They are usually stars that went nova but were too small to collapse and form a black hole.

      A handful of super-massive black holes could probably cover this tripling of the stars.

      Even if the amount of matter tripled, however, it still would not eliminate dark matter. Currently, visible matter accounts for 4.6% of the matter in the observable universe. Dark matter accounts for 23% (the res

  • by Mitchell314 (1576581) on Wednesday December 01, 2010 @07:08PM (#34411612)
    It's full of three times the stars.
    • How many library of congresses is that?

      • Three times as many as before.

        • by Nidi62 (1525137)
          But is that 3 libraries of congress or a library for 3 congresses?
          • by mug funky (910186)

            congressmen can't read, duh.

          • by dgatwood (11270)

            No, spelled that way, it's more likely an adult book/movie rental house. Different kind of "congress".

    • by Cow Jones (615566)

      Even so, I'd say there are still billions and billions [youtube.com] of them.
      "We have always been space travelers [youtube.com]." - Carl Sagan

    • It's full of three times the stars.

      And that song about Van Gogh should have started "Starry, starry, starry, starry, starry, starry night".

  • by Verteiron (224042) on Wednesday December 01, 2010 @07:25PM (#34411820) Homepage

    The Chirpsithra will be thrilled.

    • by Surt (22457)

      Sadly, this discovery shows just how incompetent a painter he was. There should have been three times as many swirlies. Or maybe he was just lazy. Anyway, I'm sure others will chalk it up to 'artistic license' rather than out their favorite painter as the fraud that he was.

  • by spongman (182339) on Wednesday December 01, 2010 @07:43PM (#34411966)

    it's more full of stars!

  • by Nyder (754090) on Wednesday December 01, 2010 @08:33PM (#34412438) Journal

    Nice, more stars.

    can't wait to take my telescope out and look at them.

    wait, what?

  • What does this mean for the mass of the Universe? Has the estimated quantity of dark matter been overestimated?
    • > What does this mean for the mass of the Universe?

      Nothing. It just means that more of the baryonic matter is in the form of dim red dwarf stars than we previously had estimated.

  • ...the astronomer wasn't just hit on the head with a cartoonishly large wooden mallet?

    .
  • by davidc (91400)

    It's full of stars!

  • is getting tantalizingly close. Ok, half way to go, but maybe there are more eliptical galaxies.

    The pot heads would be insufferable.

  • It seems to me that this discovery yielded a change in the calculated number of stars in the universe, while doing next to nothing about "the total number of known stars in the universe".

  • by isorox (205688) on Thursday December 02, 2010 @03:40AM (#34414588) Homepage Journal

    The human mind just can't really cope with large numbers. The universe is just so shockingly enormous, on the order of 10^80 atoms.

    However, this is a tiny number in comparison with others. The number of possible chess games is on the order of 10^123. You'd have to encode 100000000000000000000000000000000000000 games of chess into a single atom to store every possible game.

    Of course, you'd need 10^183,800 monkeys to write Hamlet on the first go.

    These number all seem the same to me though, on the same order of 10^50 (number of atoms on the earth)

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