Hoag's Object

(en.wikipedia.org)

130 points | by ani-ani 1525 days ago

5 comments

  • CliffStoll 1524 days ago
    As a summer student at Kitt Peak Observatory in 1974, I had the honor of working with Art Hoag. Not just a brilliant astronomer and a super efficient observer. Art was a true gentleman of the old school: kind to students and quite progressive. Forty five years ago, over night-lunch at the observatory, he told us of the importance of bringing into astrophysics more women, minorities, gays, and foreign students.
    • michaelmcdonald 1524 days ago
      Wait....Is this the account of THE Cliff Stoll? Author of “The Cuckoo’s Egg”?
      • hanniabu 1524 days ago
        For those not aware of this book, I just looked it up and found a video enactment of it starring cliff Stoll on Youtube. Started out slow, but after a few minutes in when they started getting into the details I was hooked. Looks like I just lost an hour tonight, lol.

        https://www.youtube.com/watch?v=qubEamdc4Ng

      • daeken 1524 days ago
        Yes! Blows my mind every time I see him comment. It's amazing folks like him who keep me coming back here.
    • gerikson 1524 days ago
      How hard is it as an observational astronomer to adapt to "night mode"? I'm guessing it's like night-shift work, tough on family and social life.
      • ncmncm 1524 days ago
        "How do you keep warm, up on the mountaintop at night?"

        "We don't."

        Astronomy is more comfortable nowadays. It can be done from anywhere.

  • mkaic 1525 days ago
    Very cool that there’s a second ring galaxy you can see by looking through the first one! And here I was not even knowing ring galaxies existed until today!
  • bmgxyz 1525 days ago
    It's neat that such an interesting and pleasing object just happens to be facing us.
    • martinpw 1525 days ago
      Maybe that is a selection effect. Objects like this that are more inclined will tend to look more like regular galaxies so will not be identified as ring galaxies so easily.
      • finnh 1524 days ago
        well sure.. but if one average an arbitrarily chosen vantage point (ours) sees only one of these so well, then we can infer that many other arbitrary vantage points see none. and that would be sad.

        (i know the article mentions others, so this might not hold up to a full cataloging of our night sky)

    • jhanschoo 1524 days ago
      We have classified very many galaxies, so a couple neat and unusual ones is probably little surprise.
  • zabzonk 1525 days ago
    A somewhat bigger Ringworld? https://www.wikiwand.com/en/Ringworld Which, by coincidence, I am currently re-reading.
    • sneak 1525 days ago
      A classic! I’m working on the Culture novels now, which have their own variant (“orbitals”), minus the shadow squares or central star. Can’t recommend them enough, so far.
      • mkl 1525 days ago
        Orbitals, while enormous (greater surface area than earth), are much smaller. The Culture novels do have Ringworld-sized rings as well, though. E.g. from Consider Phlebas, flying under the orbital Vavatch: "It was like flying upside-down over a planet made of metal; and of all the sights the galaxy held which were the result of conscious effort, it was one bested for what the Culture would call gawp value only by a big Ring, or a Sphere."
    • tlbsofware 1525 days ago
      I can hear the halo music already
  • phkahler 1525 days ago
    This structure seems like it should not be stable. If the middle part were not centered, it would be gravitationally attracted to the ring.
    • AnimalMuppet 1525 days ago
      If I understand correctly, the middle part far out-masses the ring. If the middle part were not centered, then the ring could continue to peacefully orbit it, as the planets orbit the sun, even though their orbits are not (quite) centered on it.
      • phkahler 1524 days ago
        Ok, then the ring would be pulled in. But only to the extent that it behaves like a solid which it isnt.
    • bmgxyz 1525 days ago
      It seems the story of how this galaxy formed remains unknown.

      > Many of the details of the galaxy remain a mystery, foremost of which is how it formed. So-called "classic" ring galaxies are generally formed by the collision of a small galaxy with a larger disk-shaped galaxy. [...] However, there is no sign of any second galaxy that would have acted as the "bullet", and the likely older core of Hoag's Object has a very low velocity relative to the ring, making the typical formation hypothesis quite unlikely. [...]

      > A few other galaxies share the primary characteristics of Hoag's Object, including a bright detached ring of stars, but their centers are elongated or barred, and they may exhibit some spiral structure. While none match Hoag's Object in symmetry, this handful of galaxies are known to some as Hoag-type galaxies.

      I offer no hypothesis of my own (not least because this is outside my field), but it does seem odd to me as well. Is it possible that our mechanical intuition fails at such a large scale?

      • phkahler 1524 days ago
        My completely speculative thought is that a smaller galaxy rotating the other direction collided near the center. The angular velocities cancelled in the inner region and that all collapsed to a dense slower core. That just seems unlikely, but then again it's an unusual galaxy.
    • ur-whale 1525 days ago
      >This structure seems like it should not be stable

      Mmmh ... not sure that you can easily apply intuition to N-body problems.

      • mcguire 1525 days ago
        Sure you can. The intuition is that they're not stable. The ones that are, are special cases.