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.
The mysterious red areas in M33 Triangulum Galaxy are regions of high concentration of hydrogen gas and young, hot stars. They appear red due to the ionization of hydrogen gas by the intense radiation from these young stars.
These red areas were first discovered by the Hubble Space Telescope in the late 1990s. Since then, other telescopes and instruments, such as the Spitzer Space Telescope, have also captured images of these regions.
The formation of these red areas is due to the ongoing process of star formation in the Triangulum Galaxy. As gas and dust collapse under their own gravity, they form new stars. These young stars emit large amounts of ultraviolet radiation, which ionizes the surrounding hydrogen gas and causes it to glow red.
No, similar red areas have been observed in other galaxies as well. These regions are often called H II regions, named after the ionized hydrogen gas they contain. Other galaxies, such as the Andromeda Galaxy and the Milky Way, also have these red areas due to ongoing star formation.
By studying these red areas, scientists can learn more about the process of star formation and the properties of young, hot stars. They can also use these regions as indicators of the overall health and activity of galaxies. Additionally, the data collected from these areas can help us better understand the evolution of galaxies and the universe as a whole.