Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Question on M33

  1. Sep 19, 2011 #1

    Drakkith

    User Avatar

    Staff: Mentor

    In this picture I took of M33, the Triangulum galaxy, what are the small red areas scattered about in the galaxy? Some sort of star clusters?

    [PLAIN]http://img708.imageshack.us/img708/4899/m33c.jpg [Broken]
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Sep 19, 2011 #2

    turbo

    User Avatar
    Gold Member

    Star-forming regions. Think of the Orion nebula.
     
  4. Sep 19, 2011 #3

    Drakkith

    User Avatar

    Staff: Mentor

    Ah ok. Thanks turbo!
     
  5. Sep 19, 2011 #4

    turbo

    User Avatar
    Gold Member

    No problem. Those clouds probably contain copious amounts of dust, too, but we can't see them because they don't radiate in visible light. It would be interesting to look up infrared images of nearby galaxies and see if we can "see" dust clouds in those wavelengths. Might have to try that sometime.
     
  6. Sep 19, 2011 #5

    Drakkith

    User Avatar

    Staff: Mentor

    Yeah I'm pretty sure I've seen an image of the Sombrero Galaxy taken in infrared that showed lots of dust.

    Edit: Check out here: http://en.wikipedia.org/wiki/Sombrero_galaxy
    It has an infrared photo that shows "polycyclic aromatic hydrocarbons (PAHs) within the dust ring"
     
  7. Sep 19, 2011 #6

    turbo

    User Avatar
    Gold Member

    Thanks for that link! Pretty amazing. I have been working with old Schmidt camera images (IRSA) for years to study links between apparently-interacting galaxies. I should take off the blinders and get into the IR, XR, and other bands to see what's new out there. The trick is: is the differential in redshifts of apparently-interacting galaxies reasonably expected to be within the ranges that we anticipate using GR? We can use the estimated masses of the galaxies to estimate the range of peculiar motions that smaller galaxies might be allowed to have with respect to their larger hosts, but often the redshift differentials are not viable.

    There is probably a whole lot more evidence(or room to discover evidence) for interaction once you get out of the visible and near-IR. I have recently heard from a friend that Halton Arp is in poor health. I'd love to extend our study of apparent physical interactions between galaxies of discordant redshifts to support Arp's work. He is a very polite and gentlemanly person, and he contacted me out of the blue after Astronomy sent one of my missives his way.

    Edit: I commented on an article about apparently-interacting astronomical objects, and mentioned Arp in passing. Apparently, that was enough to trigger the forwarding of my comments to him. I'm glad. I got some pretty neat insights into Hubble's mind that way.
     
    Last edited: Sep 19, 2011
  8. Sep 19, 2011 #7

    Drakkith

    User Avatar

    Staff: Mentor

    What is this IRSA thing and what exactly where you studying?
     
  9. Sep 19, 2011 #8

    turbo

    User Avatar
    Gold Member

  10. Sep 19, 2011 #9

    Drakkith

    User Avatar

    Staff: Mentor

    Neat! I've never heard of Halton Arp till just now, so I don't have an opinion on him or his theories. (That I just looked up on wikipedia lol)
     
  11. Sep 19, 2011 #10

    turbo

    User Avatar
    Gold Member

    Arp is one of the best old-school observational astronomers. When he got enough time on big scopes to get some decent spectroscopy, he discovered that the smaller galaxy in interacting pairs generally had higher redshifts. This idea had no legs back when the BB (redshift=distance) paradign had gained ascendance and was the flavor of the week. He may be absolutely wrong, but still the way that he was dumped by Cal Tech without peer-reviewed refutation was insulting at best.
     
  12. Sep 19, 2011 #11

    Drakkith

    User Avatar

    Staff: Mentor

    You don't always have to be wrong, the other side can just be more convincing.
     
  13. Sep 22, 2011 #12
    Halton Arp became a crackpot in his old age. He denies The Big Bang theory.
     
  14. Sep 22, 2011 #13

    turbo

    User Avatar
    Gold Member

    Halton Arp and quite a few other observational astronomers were unconvinced that all redshift not attributable to peculiar motion and gravitation was necessarily a result of cosmological expansion. Hubble himself never made that leap, despite the BB proponents' tendency to laud him as the discoverer of the BB. Much of science (including projects, funding, prestige, etc) is politics, and public perception is critical. When I was in High School, my science teacher managed to get a bit of funding to bus a bunch of us kids (two grades, actually) to Andover, ME to the Telstar site for a tour. We were told in no uncertain terms that the residual temperature in the telescope's signal (CMB) was the thermal echo from the BB.

    Arp is not a nut or a crackpot. He is a product of his times, and there are still people following up on his observations.

    http://arxiv.org/abs/astro-ph/0203466

    An older paper, but still quite relevant.
     
  15. Sep 23, 2011 #14

    Chronos

    User Avatar
    Science Advisor
    Gold Member

    Arp was an acclaimed and accomplished observational astronomer, which was never questioned. He was, unfortunately, politically inept - which prevented him from achieving his full potential.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Question on M33
  1. A question. (Replies: 5)

  2. Question ? (Replies: 2)

  3. A question (Replies: 2)

  4. Questioning Gravity (Replies: 7)

Loading...