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Newly Found Planetoid Possibly Larger than Quaoar

Posted by michael on from the deep-space-one dept.

I am Jack's username writes "A newly discovered planetoid (Google news cluster) 2004 DW in the Edgeworth-Kuiper belt, where some think objects larger than Pluto exist, may be larger than Quaoar - making it the second largest known trans-Neptunian object and 18th largest object in the solar system."

4 of 46 comments (clear)

  1. Question for the astronomers among us... by Baron_Yam · · Score: 4, Interesting

    Given that stars (excluding the Sun) are point sources as far as our current telescopes are concerned, and these KBOs are discs... what are the odds of a KBO eclipsing a given star during a standard observation period?

    Things I don't know: 1) density of KBOs vs stars 2) apparent speed of KBOs relative to the stars beyond them. 3) The average length of time any star is in a field of observation at a major telescope.

    Actually, there's probably a lot more I don't know, that's just what comes to mind at the moment.

    1. Re:Question for the astronomers among us... by Birger+Johansson · · Score: 2, Interesting

      Ordinary asteroids in the inner solar system sometimes pass in front of weak background stars (occultations), which provides the opportunity to measure their diameters by timing the disappearence and reappearence of the star. Sometimes such occultations even have revealed the asteroid to be binary.
      However, such events are rare, even for close-by asteroids. The angular diameter of far-away Kuiper-Edgeworth objects is so small that they almost never pass in front of a catalogued star.
      -The basic idea is sound, it is just very unlikely that a K-E object will pass in front of a star that is under observation.

    2. Re:Question for the astronomers among us... by Gary+Bernstein · · Score: 3, Interesting

      The answer is: choose a star near the ecliptic plane of the Solar System and watch it carefully. About once per thousand years, a KBO will pass in front of it. This will make it dim out for a little less than a second, on average. This is a good way to look for small KBOs, not the rare big ones like 2004 DW. Seem like a tough job? It gets easier if you can watch many thousands of stars at a time, then you might see a few events per year. This is exactly what will soon be attempted by my friends at the Taiwanese-American Occultation Survey (TAOS). Should be starting up later this year.

  2. Comparing trans-Neptunian objects by geoswan · · Score: 2, Interesting
    The discoverers of this object keep refering to which of these objects are closer than others of them. Well, hold on, they are all in a 3:2 resonance with Neptune, orbiting the sun twice for every three orbits Neptune makes.

    So, is it really all that meaningful to compare them based on their distance from us today? If they all share the same period don't they all have the same, um, I don't know what it would be called... But their kinetic energy per unit mass would all be the same.

    If they all have the same period, then wouldn't their average distance from the Sun be directly proportional to the eccentricity of their orbit?