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Stellar Snow Globe Mystery Solved With Hubble’s Help

This new NASA/ESA Hubble Space Telescope image shows the globular cluster IC 4499.
This new NASA/ESA Hubble Space Telescope image shows the globular cluster IC 4499.

A cosmic archaeological dig has unfolded within a giant ball of stars some 55,000 light-years away, courtesy of NASA’s Hubble Space Telescope.

The famed orbiting observatory has snapped this amazing portrait of IC 4499, a globular cluster of stars that resides just outside of the disk of our Milky Way galaxy. The star cluster is just one of hundreds suspended in a halo around our galaxy that are thought to contain seem of the oldest stars in the universe. Many of the stars are more than ten billion years old.

Now however,  Hubble’s keen eyesight has dug up the details of this particular globular cluster’s stars, which reveal its overall age.

Cosmic Oddball

Astronomers had long believed that all the stars that make up a cluster should have formed at the same time, making it easy to determine their age. But actual observations show that the largest globulars are peppered with stars of varying vintages. One possible reason: the giant cluster’s intense gravity would pull in any gas and dust  wandering too close by and use it to cook up new stars.

IC 4499 turns out to be kind of a cosmic oddball in terms of its mass, lying somewhere in the middle weights of the more common high and low mass clusters.  This unique property of IC 4499 has now allowed astronomers to explore how mass can affect how these cosmic fossils evolve.

Hubble observations show that despite its mid-size mass, all of IC 4499’s stars belong to a single generation of stellar births. This single fact has now led to an accurate age dating of the entire globular cluster, a determination that had eluded astronomers for decades.

The new data suggests that IC 4499 is about the same age as the other globular clusters buzzing around the Milky Way—some 12 billion years old.

See for Yourself

Shining at a lowly tenth magnitude, IC 4499 is a faint target for backyard telescopes using high magnification in the Southern Hemisphere. To track it down it’s best to start off by identifying the constellation Crux, the Southern Cross, halfway up the southern sky late evening in August.

IC 4499 lies in the neighboring tiny, faint constellation Apus, the Bird of Paradise. Draw an imaginary line between the brightest star in Apus and the next star to its left, Delta Octantis. The globular cluster lies just above that imaginary connecting line.

This  sky chart shows the southern evening sky as seen from the Southern Hemisphere late August. Using a telescope and a low power eyepiece scan the region in the constellation Apus, to the lower left of its lead star Alpha Apodis. Credit: SkySafari
This sky chart shows the southern evening sky as seen from the Southern Hemisphere in late August. Using a telescope and a low-power eyepiece, scan the region in the constellation Apus, to the lower left of its lead star Alpha Apodis. Courtesy   SkySafari

But if you really want to get a sense of the true majesty of what a globular cluster looks like, there are much brighter counterparts in the southern sky. Arguably one of the most beautiful is Omega Centauri, nestled within the bright constellation of Centaurus. Located just 17,000 light-years from Earth, it is the closest and brightest globular cluster in the entire sky. It spans 175 light-years and contains a few million stars.

This wide-angle sky chart shows the sky as seen from Australia. Looking towards the SW in the early evening Omega Centauri globular cluster is an easy binocular target.  Credit: SkySafari
This wide-angle sky chart shows the sky as seen from Australia. Looking toward the southwest in the early evening, the Omega Centauri globular cluster is an easy binocular target. Courtesy SkySafari

For those of us in the Northern Hemisphere, there is another famous cousin, the Great Hercules Cluster, which is a favorite target for backyard telescopes. Hanging halfway up in the western sky in evenings at the end of August, it resides in the constellation Hercules, the Strongman, and it will be easy to hunt down, thanks to four stars that make up a keystone pattern there.

Nestled within is the great binocular/telescope showpiece, the Great Hercules Cluster, or M13.

This wide scale sky chart shows the view towards the western horizon late night on August 24, and the Hercules constellation between the bright stars Arcturus and Vega. The Great Hercules Cluster, M13 can be found within the chest of the mythical hero. Credit: SkySafari
This wide-scale sky chart shows the view toward the western horizon late night on August 24, and the Hercules constellation between the bright stars Arcturus and Vega. The Great Hercules Cluster, M13, can be found within the chest of the mythical hero. Courtesy SkySafari

Located about 24,000 light-years from Earth, this globular cluster is made up of a swarm of half a million stars packed into a ball, stretching more than 100 light-years across.

This sky chart shows the location of M13 within Hercules' keystone stellar pattern. The insert is an image that shows the hi-power view through a telescope. Credit: Starry Night Software
This sky chart shows the location of M13 within Hercules’s keystone stellar pattern. The insert is an image that shows the high-power view through a telescope. Courtesy Starry Night Software/A.Fazekas

 

On dark, moonless nights, away from city lights, M13 can be glimpsed with the naked eye, appearing as a faint, small, fuzzy patch.

Clear skies!
Follow Andrew Fazekas, the Night Sky Guy, on Twitter and Facebook.

Comments

  1. john pawson
    England
    September 13, 4:07 pm

    Boffins are always coming up with ‘previously unknown ‘ discoveries. “The big bang” has now had celestial spanner thrown into doubt as envisaged because of the amount or lack of lithium detected in the stars! Black Holes are something speculated by Einstein.
    So tomorrow it’ll be something else that to me is the fascination of space/universe

  2. sarmat
    Russia
    September 8, 11:51 am

    Carlo, I guess there were clusters that fell. As well as there were planetoids that either fell or went away thoughout our Solar System’s history.
    What I can think of?
    Apart from the Universe expanding – which makes bye-byes more probable than hellos, tidal forces often expand the system rather than contracting it – the latter case being likely when there is a rather dense medium within it to implement friction and energy loss (scattering).
    Besides, nobody said the cluster was formed nearby.. Like it “spiralled” onto the galaxy – but when it reached a certain distance/orbit, the initial rather dense medium must’ve got either/both dispersed and/or sucked in by the surviving objects (like this “humble servant”;).
    Don’t forget we do not observe any “first” nor ‘final’ moments in any evolution, and in any evolutionary moment there’s always something, and that something is moving – but we can’t “clearly see” the movement, we only see “snapshots” of various system states – depending on where we’re looking: the farther we look the older ‘snapshots’ we’re gazing at.

  3. Felix Kwan
    Sabah, Malaysia.
    September 1, 8:15 pm

    The more discover from outer space, more puzzle to the scientists. It is a great pleasure for us in the third world to learn what the scientists gave us. Thanks National Geographic share us new discovery.

  4. Youdhvir Chahal
    india
    September 1, 1:39 pm

    I think there may be a much much greater black hole at the center of the universe, around which all these galaxies etc are going around. we might be too far away from it to have experienced it as yet.

  5. Ash Scar
    September 1, 11:02 am

    Carlo Franco,
    I enjoyed reading your comment, but do you REALLY expect anyone to be able to answer your questions..? LOL

  6. Carlo Franco
    August 26, 1:01 pm

    Hi, I have a few questions and I hope someone could answer them. If the globular clusters buzzing around the Milky Way are some 12 billion years old that ‘only’ leaves about 1.7 billion years between their formation and the Big Bang right?!

    But what I’m wondering about is how come that all the clusters are not swallowed up by the huge gravitational field of our Galaxy in all those years?

    OK, they could have been formed far away from our Galaxy and then drifted towards it, but even then there are hundreds of them swirling around our Milky Way, and although they all have their individual age & origin they all seem to dance around our galactic disk without being usurped by it. Or perhaps they do fall into our galactic disk at some point, but it takes an awful long time…

    Could it be that these stars are expelled from our Galaxy and then formed these globular clusters?

    Or, given the notion that there’s a big black hole at the center of our Galaxy, couldn’t it be that the pure energy ejected from that black hole is the basis for raw material to form these globular clusters? Or perhaps that beam of energy pulls so much Hydrogen with it that this is the fueling system of which these globular clusters are born from?

    If so, that would be a closed loop system, like our weather. Water evaporates, condenses to make clouds, and after it rains it flows back to the ocean. Could this pattern also occur in our Galaxy?

    Giant molecular clouds of gas have formed the stars, they then arrange themselves into a galactic disk, in which they seem to swirl to the middle where they get absorbed by that black hole and spewed back outwards, to form new clouds of gas… and the cycle starts all over again. Could this be a looped system like our weather system?

    Another question I have is related to the Big Bang itself.
    Imagine a giant soccer ball, with the center being the cradle of the Big Bang & the edge of that ball represents the farmost expanding edge of the current universe.

    Actually I have two questions, one being about the expansion. They say that the expansion is still ongoing, even accelerating, but if you can imagine the edge, that is pushing itself outwards, in a space that wasn’t there before, because the space where the expansion is traveling through is actually being created as it moves along, is it really pushing against nothing as time and space inflates? I mean if the spherical bubble, what we call the universe is still expanding, and given the notion that the space it travels through wasn’t there before, against or in what fabric of Space is it expanding? What lies just an inch away of the most outer edge of this expanding bubble?

    My second question is about the center.
    The Big Bang happened at a certain spot right?!
    Since then it has been expanding outwards, but I wonder if that spot where everything came into existence is still emanating raw material, as it did in the first second?

    If it does that would means a continuous stream since the dawn of time right?

    But if it doesn’t beam out stuff anymore, and the expansion is still ongoing, that would mean that at some point we ought to see the last bit of material spewed out as it moves along with the expansion.

    One could compare it with an erupting volcano.
    There’s an ignition, the eruption, and an expanding cloud of dust & debri. Also here we have an outer edge that is expanding, and as long as that volcano keeps erupting there’s an origin where it all came from, but once that spot dries out (sort of speak) there’s also an edge on the inside of that expanding cloud right?! (i.e. the last bit of material spewed out.)

    If so we’re headed towards a big rip. Everything keeps expanding into oblivion. Unless there’s a maximum to the farmost edge the expansion can push things, and then it falls back to the center. Akin to that looped system I described earlier… If so we would live in a perpetual, self-rejuvenating universe.

    Material is blasted into space, from the same area where the Big Bang originated from, then forms stars & galaxies, who are pushed outwards by the expansion, and when that reaches it farmost edge it kinda falls back to the center, and the whole cycle starts again…

    One could say its recycling avant la lettre ;)

    I’m no scientist, and certainly not a religious type but I do love to ponder about these things. Hopefully someone smarter than me can offer some answers.

    Thanks!

  7. admiralbrown
    Central Connecticut
    August 25, 11:31 am

    Bev Grod,
    There are many ways to determine the ages of stars. Stars are heavy and have a large gravitational field. The gravity compresses the material in the sun and heats it up like the way a bicycle pump gets hot from compressing air. When there is enough pressure the hydrogen in a star goes through fusion to become helium. The energy from fusion expands the star. The more a star weighs the hotter it burns and the shorter it lives. It is fairly straightforward to calculate how long a star will live by how bright it is, and that tells you how heavy it is. So if you look at a cluster of stars and look for the brightest star in the cluster you know the upper limit of how old that star can be.
    Also different gases give off different lights, like the bright yellow/orange in a campfire is from Sodium being heated up. Hydrogen makes a different light than Helium. You can measure the light from hydrogen and the light from helium and make a ratio. Helium is the waste from Hydrogen fusing, so the older the star is the more Helium waste there will be.
    I have oversimplified this, but the science is fairly well proven. The biggest problem with science today is the scientists are not very good at presenting their theories and the data that supports them. At the same time the science deniers are pretty slick in presentation and are very good at cherry picking only the data they want to use and ignoring most of the evidence.

  8. Bev Grod
    Canada
    August 25, 9:37 am

    How do they know how old the stars are? I know there is a lot of science behind today’s knowledge of astronomy so this might not be a simple question, but I always wonder how much is proven when I read very confident conclusions and explanations for observations and phenomena in space.

  9. CAROLYN NEUMAN
    Morro Bay CA
    August 24, 6:36 pm

    Breathe taking and elegant! Wish our warring world leaders would take a good long look at this display of the majesty of our universe.