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Oldest Planet Ever Discovered

Posted by CowboyNeal on from the brand-new-old-stuff dept.

crymeph0 writes "NASA has found the oldest known planet in a globular star cluster in the constellation Scorpius. At 13.7 billion years old, it's just slighly (~1 billion years) younger than the universe itself. Get more info from HubbleSite"

29 of 370 comments (clear)

  1. Having taken one semester of astrophysics... by Valar · · Score: 4, Interesting

    at not being an expert by any means, I wonder how they detected it. I assume (because it is so massive and in a binary system) they detected it by the normal "wobble" method. Does anyone know?

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    Crudely Drawn Games
    1. Re:Having taken one semester of astrophysics... by Jarlsberg · · Score: 5, Informative

      Yup. Here's info from Hubblesite: The story of this planet's discovery began in 1988, when the pulsar, called PSR B1620-26, was discovered in M4. It is a neutron star spinning just under 100 times per second and emitting regular radio pulses like a lighthouse beam. The white dwarf was quickly found through its effect on the clock-like pulsar, as the two stars orbited each other twice per year. Sometime later, astronomers noticed further irregularities in the pulsar that implied that a third object was orbiting the others. This new object was suspected to be a planet, but it could also be a brown dwarf or a low-mass star. Debate over its true identity continued through the 1990s.

    2. Re:Having taken one semester of astrophysics... by astrophysics · · Score: 4, Informative

      Sort of... The planet is in orbit around a binary consisting of a pulsar and a white dwarf. Previously, the pulsar had been observed and small variations in the arrival times of the pulses allowed them to detect the white dwarf companion. Further analysis of the pulsar arrival times allowed them to infer the existance of another distant companion, but there was still considerable uncertainty in the mass and orbit, so it wasn't clear if it was a planet or brown dwarf. These new observations pin down the mass of the white dwarf, which, when combined with several additional years of pulsar timing data, demonstrate that the mass is about 2.5 Jupiter masses.

      But, the really interesting part of this paper is that since they now have directly observed the white dwarf around the pulsar, they can measure its colors and infer it's age. Previously, there were two leading theories... 1. That there was a pre-existing pulsar-white dwarf binary and then the planet was captured from it's orbit around a star which passed by the pulsary-white dwarf binary. -or- 2. There was a pulsar-star binary which interacted with a star-planet binary, kicked out the original star, replacing the old stellar companion with the new star, and leaving the planet in a wide orbit. The new star evolved, expanded, transfered mass onto the pulsar, spun up it's rotational speed, became a white dwarf, and circularized it's orbit around the pulsar. The planet stuck around in a wider orbit and perturbed the inner binary slightly, imparting a small eccentricty to the pulsar-white dwarf binary.

      Since we now know the white dwarf is young, scenario 2 is vastly more likely, and so we now better understand the formation mechanism for this system. That's the real news behind this discovery.

      BTW- The original paper is avaliable in today's issue of Science and I think it should be readable for someone with one college astronomy class.

    3. Re:Having taken one semester of astrophysics... by KDan · · Score: 4, Informative

      For those who don't know what an H-R (Hertzsprung-Russel) diagram is, it's a diagram plotting all the stars in a graph with the following axes: Temperature (which can be measured accurately by looking at the spectrum of the star), and (absolute) Luminosity.

      The thing to realise for the non-initiated here is that stars move around the H-R diagram throughout their life-time, as they form, expand into red dwarfs, blow away their outer shells, shrink into white dwarfs, etc. Through all this their temperature varies and their luminosity (which is largely dependent on their size, which changes vastly between, say, a star like the sun and the same star 5 billion years later when it's turned into a red giant) varies too.

      However the vast majority of the stars in a cluster of average age will be stuck on a line which represents what is called the "main sequence", which is what our sun is on. Where they are on the line depends on their starting mass. Stars stay on the main sequence longer if they are lighter (heavy stars have much shorter lives), so there is a "turn-off" point on the main sequence line (a point where the stars move off the main sequence into the red giant phase) which can be used to evaluate the age of the cluster, assuming all the stars formed at roughly the same time.

      Daniel

      --
      Carpe Diem
    4. Re:Having taken one semester of astrophysics... by Rogerborg · · Score: 4, Funny

      It's a four step process.

      • Declare exactly what sort of infinitesimal readings you expect object X to produce, should it exist.
      • Declare that you have found that infinitesimal reading, thereby proving both the existence of object X and the validity of your theory.
      • ...
      • Tenure!
      --
      If you were blocking sigs, you wouldn't have to read this.
    5. Re:Having taken one semester of astrophysics... by jafiwam · · Score: 4, Informative

      Yeah, 100 times a second, a normal star would fly apart, pulsars are not normal stars though and can withstand that spin due to how they are made. (100/s is actually pretty slow, 1K/s and 10K/s are also out there.)

      Pulsars are nutron stars (collapsed due to gravity to the point of overcoming the repulsive force between atoms, so the nucleus of the atoms are smashed together, extremely high density matter just short of a black hole in density) where the angular velocity of the entire system is packed into a tiny space (meters or a few kilometers across).

      Since it still has a magnetic field too, there is a "beam" of photons that get channeled out away at the poles, sorta like a flashlight spun on a string.

      If earth is in the beam, we see a "pulse" of light energy coming from the star. (There's a proably a bunch we do not see as they do not point at us at any time during the spin.)

      Counting the pulses tells you how fast the star is spinning and to a certain extent it's age (as the pulse slows down over astronomical time).

      Since the spin has a lot of angular momentum (A LOT) it is extremely regular, and serves as a nice clock to use against stuff going on around the pulsar and between us and it. (Think atomic clock to synch GPS with, same concept.)

      Or something like that.

  2. A planet younger than the universe? by pilybaby · · Score: 5, Funny

    Now that IS impressive!

  3. Heavy elements by ramk13 · · Score: 5, Interesting

    What struck me the most from reading about it is that enough heavy elements (Fe, Si, etc) were around at the time to form the planet. That was one of the main reasons it was thought that planets couldn't have formed that early - you only had light gases around. So apparently it doesn't take a few billions years of fusion to get enough solid material for a planet. I wonder what other changes this will bring about in terms of the search-for-life campaign. The window just got a little bigger.

    1. Re:Heavy elements by astrophysics · · Score: 4, Informative

      Yes, this is another interesting aspect of the story. We now have a much firmer constraint on the planet's mass, so if you define planets and brown dwarfs by their masses, then we are much more confident that it is a planet, and not a brown dwarf. However, we still don't know how it formed. Traditionally, brown dwarfs are assumed to form by direct collapse, while planets are assumed to form first by accreting a rocky core. Of course, we don't really know how this "planet" formed. Alan Boss advocates that it may have formed via direct collapse, like a brown dwarf, in which case the low metal abundance probably isn't so important. However, many scientists think that the accretion of a core first is more likely. Since we know that this planet exists and almost certainly formed in a low metallicity environment, that might be difficult in this case. I suspect someone will now attempt to simulate accretion of a planetary core in a low metallicity disk. I look forward to reading about their results.

    2. Re:Heavy elements by tbone1 · · Score: 4, Informative
      This isn't entirely odd. Theories may have changed since I was in grad school ten years ago, but back then it was thought that the first generation of stars would produce an abundance of massive, quick-dying, supernova-candidate stars. (This is because only H, He, and a bit of Li existed; long story.) This is where you get things like Fe, Si, etc, forming. Also, the deaths of the two stars in the center of the stellar system may have "enriched" the planet.

      It is odd, but not completely unexpected.

      --

      The Independent: Reverend Spooner Arrested in Friar Tuck Incident - ISIHAC, Historical Headlines
  4. I understand now... by borgdows · · Score: 5, Funny

    NASA has found the oldest known planet in a globular star cluster in the constellation SCOrpius.

    Go back to your planet Darl!

  5. Re:In case of slashdotting - full text of report by ramk13 · · Score: 5, Funny

    I'm sure the *New York Times* runs for cover everytime /. links one of it's stories. I heard they just upgraded from 128k DSL to 384k cable, so maybe they can handle it this time. If they can't you have them covered, don't you?

  6. Re:universe age by Valar · · Score: 4, Interesting

    You judge the age of fairly close objects, using nuclear models, compare with red shifts. Then you look at the red shift of far away objects and try to extrapolate age, IIRC.

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    Crudely Drawn Games
  7. Detecting planets. by asciimonster · · Score: 5, Insightful

    It's a pity that we still have to detect planets by there gravitational pull on the suns they orbit. This will only alow us to "see" gaseous giants (like jupiter) who have lotsa mass. The earth-like planet have much too little mass to ever see with this method.

    I know people are tring to detect the reflection of the stars (of it's sun) light, but that's pretty hard since you have to filter it out from the light directly recieved from that star. But if we would really try and be lucky, could we see the planet directly when another planet is blocking our view of the star?

    Just my $0.02. $0.04 with inflation correction and VAT.

    1. Re:Detecting planets. by Valar · · Score: 4, Informative

      Ah, but if our solar system is anything like a normal solar system and/or the computer models are true, then systems with large, detectable planets probably have smaller planet as well. Some of them might even be similar to Earth in size and composistion.

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      Crudely Drawn Games
    2. Re:Detecting planets. by Random+Walk · · Score: 4, Informative
      First, towards 2010 those searches using radial velocity variations (i.e. 'gravitational pull', 'wobble') will become sensitive to Jupiter-like planets (planets detected so far are typically more massive than Jupiter, and closer to their parent star), thus planetary systems like ours will become detectable (Jupiter has a 12-year orbit, thus the main problem is the long time baseline required).

      Second, there are several projects planned, like the 'Darwin' project of the European Space Agency (ESA) that will specifically target earth-like planets. Here is a short description of Darwin, and links to some other projects.

  8. Re:In case of slashdotting - full text of report by Valar · · Score: 4, Funny

    And in case the comment db holding his slashmirror gets slashed:


    Oldest Planet Is Revealed, Challenging Old Theories By JOHN NOBLE WILFORD

    In new observations of a distant region of primitive stars, astronomers have found the oldest known planet, a huge gaseous object almost three times as old as Earth and nearly as old as the universe itself...

    Just kidding.

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    Crudely Drawn Games
  9. I wonder... by mikeophile · · Score: 4, Interesting
    How many civilizations have looked at Sol with their telescopes and determined the presence of Jupiter from our star's wobble?

    Would they conclude that it was unlikely that life could evolve in this system for one reason or another based upon their own standards?

    1. Re:I wonder... by mikeophile · · Score: 4, Interesting
      I think you've missed the point.

      There are several planetary systems that we have discovered that have been ruled out as having evolved life as we know it.

      The system in the article is a prime example.

      The x-ray emissions from the pulsar would prevent life as we know it from ever starting, much less evolving.

      Those are our standards. We have only ourselves as a basis for comparison.

      Perhaps there are very alien forms of intelligent life that would not consider our system capable of supporting biology because we lack a strong x-ray source.

    2. Re:I wonder... by tkittel · · Score: 4, Insightful

      > I mean, we humans already know (from quantum mechanics) that the concepts of space and time
      > are of limited value as models of reality, although we cannot escape the way our brains
      > are hardwired. Extraterrestrials will probably think in completely different categories, which
      > are as much beyond our imagination as space and time are to them.

      I think it is a fairly model independent assumption to say that any intelligent lifeform must be rather complex and therefore orders of magnitudes larger than the typical quantum mechanical regime of atoms and molecules.

      To be able to have a level of consciousness it is also a fairly safe assumption that the physical proportions of a being ('s "brain") must be small enough that the speed of light doesnt seriously restrict the exchange of information between the various parts of the brain.

      Therefore any (or at the very least, most) intelligent life should exist in a regime where the classic concepts of space and time are an EXCELLENT approximation to reality.

      Why you think it is UNLIKELY that they would think in concepts of space and time* is beyond me.

      *:there is btw. nothing wrong with the concepts of space and time. For instance time is NOT just a "fourth dimension" as some folks believe. And QM doesnt discard space and time.

      from-a-physicist-who-is-tired-of-the-ravings-of- ra ndom-science-fiction-fans

  10. Planet or Brown Dwarf by patch-rustem · · Score: 5, Funny
    From the article:
    Was it a planet or a brown dwarf? Hubble's analysis shows that the object is 2.5 times the mass of Jupiter, confirming that it is in fact a very large gnome.
    --
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  11. Cosmic Microwave Background by Hittite+Creosote · · Score: 5, Informative

    The most accurate estimation of the age of the universe has been recently carried out by the WMAP mission, which measured the cosmic microwave background with 35 times the resolution of the previous COBE mission. The universe is 13.7 billion years old, plus or minus 200 million years.

    1. Re:Cosmic Microwave Background by kardar · · Score: 4, Insightful

      "the universe"

      this means our universe, the universe we call home.

      but what we don't know yet, and from what I understand this is still under debate, or maybe we'll never know for sure, is whether we will one day say

      "this universe"

      as opposed to all of the other universes, past, present and future.

      I like this concept; it's kind of cool.

      I would imagine that the composition of this planet would be different from the composition of our planet, provided that the globular cluster has less "recycled" supernova remnants. Or is it possible that there had already been supernova explosions prior to the time the planet was formed? Or is this some complex interrelationsip between the white dwarf, the pulsar, and the planet? Some strange type of accretion or something? If that planet contains heavier elements, then maybe it's artificially manufactured by intelligent beings! It would be cool to check it out.

  12. Re:Heavy elements and eating into the timeframe by nimblebrain · · Score: 5, Interesting

    Well, they're begging the question somewhat, but it seems true that globular clusters metal deficient. Jupiter's atmosphere is 82% hydrogen, 14% helium and only a trace of heavier elements. Who knows what goes on at the core, but that would seem to indicate that planets don't need rock to form.

    That said, if we found some moons around it somehow at some point in the future, there would be a lot of questions that need answering.

    Is it worrying anyone else, though, how thoroughly we're cutting in to the upper estimate of the age of the universe according to Big Bang Theory? Prior guesses on the age of the universe in BBT were in the 9-12 billion range.

    Invoking tweaks on inflation theory and 'anti-gravity' via the cosmological constant, the upper limit has been moved up to 15 billion years. Now here we are with a planet... a close planet (all things considered, 7200 light years isn't that far away on a grand scale :), that's 13 billion years old plus star and cluster formation time, and some of the other observations from the furthest visible reaches coming back from ye olde Hubble... how much further can we cut into this without jeopardizing the 15 billion year estimate?

    Something to consider...

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    Binary geeks can count to 1,023 on their fingers :)
  13. Re:*Was* the oldest by Random+Walk · · Score: 4, Informative

    The planet is in a binary system with a neutron star and a white dwarf. The neutron star has already exploded as a supernova (neutron stars are the remnants of supernova explosions), and the white dwarf will never explode as supernova.

  14. It's astonishing what we can do these days by Rogerborg · · Score: 4, Insightful

    Because, you know, back when I was a little lad, new discoveries were peer reviewed and independently verified before being announced as fact. Especially so when a single data source is quoted, and especially especially so when they're based on incestuous reasoning: if we're right about what gravitational wobble should look like for bodies X and Y at distance Z, then we've just found bodies X and Y, therefore the theory is right! Tenure for everyone!

    Until we get Hubble II up there to take independent readings which can be independently analysed, this is a theory awaiting review. An exciting theory, but a theory. If you want to believe it, go ahead and believe it, but I'm in no hurry to pencil it in to my Big Book of the Universe.

    --
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  15. Been reading too much slashdot when.. by Phoebus0 · · Score: 4, Funny

    You glance at the title and see "Oldest patent discovered" and wonder what it was for and who's trying to make money from it.

  16. Re:universe age by carlos_benj · · Score: 4, Funny

    How do they know the universe is 14.7 billion years old?

    Simple. They cut it in half and count the rings....

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    As a matter of fact, I am a lawyer. But I play an actor on TV.

  17. Re:Oldest for now. by arth1 · · Score: 4, Informative
    Given a few years or even a few decades, technology would have had improved vastly that I'm sure we will see more older ones.


    Not necessarily -- or at least not for that reason. Remember that this is about as old as a planet can be, as it was formed when the universe was still quite young.
    For a planet to form, there must already have been stars going supernova to create the materials the planet forms for. And this star material must also gather in large enough concentrations close to a gravity well (i.e. a star or another planet).
    Finally, the gravity well it revolves around must be extremely long-lived for it to still exist -- alternatively, it must be at the "other side" of the universe, where we see it as it existed back then, with the probability that it no longer exists when we see it.

    Yes, I believe we will find more old planets, but not primarily because of improvements in technology, but because the universe is frigging huge, with zillions of possible old planets.
    Not MUCH older than this one, though.

    Regards,
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    *Art