The discussion revolves around the small red areas observed in the Triangulum Galaxy (M33), with participants exploring their nature and implications. The conversation touches on star-forming regions, dust clouds, and the potential for infrared observations to reveal more about these phenomena.
Participants express a range of views on the nature of the red areas in M33, with some agreeing on their identification as star-forming regions while others emphasize the importance of dust and infrared observations. The discussion on Halton Arp reveals significant disagreement regarding his theories and reputation, with no consensus reached on his contributions to astronomy.
Participants reference various observational techniques and the limitations of visible light in studying astronomical phenomena. The discussion also highlights the complexities of interpreting redshift data and the political dynamics within the scientific community.
turbo said:Star-forming regions. Think of the Orion nebula.
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.Drakkith said:Ah ok. Thanks turbo!
turbo said: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.
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.Drakkith said: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"
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.Drakkith said: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)
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.Dr_Morbius said:Halton Arp became a crackpot in his old age. He denies The Big Bang theory.