by Ann » Fri Dec 10, 2010 6:15 am
I, too, want to extend my congratulations to the team who produced this magnificent photo.
Personally I'm very interested in M 81's small satellite galaxy, Holmberg IX. This photo offers a splendid portrait of this diminutive dwarf. The galaxy appears to be made up almost exclusively of clusters and associations of young blue stars. An extended pink object to the upper right of Holmberg IX is clearly an emission nebula, and other pink objects in or near the small galaxy may be emission nebulae, too. That is interesting, because it means that the tiny galaxy still has some gas left to make stars of. To me that suggests that Holmberg IX hasn't had many supernovae yet, because such titanic stellar explosions would certainly blow all remaining gas out of the small and gravity-weak galaxy.
However, and very interestingly, at high magnification a relatively large number of very orange, starlike objects can be seen in and around Holmberg IX. What are they? It would be fascinating if they were red supergiants or deep red carbon stars, but I find that very unlikely. The orange objects are too orange and too bright compared with the other stars of Holmberg IX to be stars. Besides, no similar population of bright red stars are visible around the outer edges of M81. No, the orange objects are almost certainly distant, and therefore highly reddened, galaxies. So small blue dwarf galaxy Holmberg IX sits superimposed (from our point of view) on a distant galaxy cluster. Fascinating!
I, too, really appreciated the view of Arp's Loop. It is particularly interesting to see how this dust feature looks brownish when seen superimposed on the bright yellow bulge of M81, but the same dust feature looks blue against the blackness of space. And indeed, there are a few suspiciously pink spots inside the blue arc, testifying to the birth of young blue stars inside it.
Ann
I, too, want to extend my congratulations to the team who produced this magnificent photo.
Personally I'm very interested in M 81's small satellite galaxy, Holmberg IX. This photo offers a splendid portrait of this diminutive dwarf. The galaxy appears to be made up almost exclusively of clusters and associations of young blue stars. An extended pink object to the upper right of Holmberg IX is clearly an emission nebula, and other pink objects in or near the small galaxy may be emission nebulae, too. That is interesting, because it means that the tiny galaxy still has some gas left to make stars of. To me that suggests that Holmberg IX hasn't had many supernovae yet, because such titanic stellar explosions would certainly blow all remaining gas out of the small and gravity-weak galaxy.
However, and very interestingly, at high magnification a relatively large number of very orange, starlike objects can be seen in and around Holmberg IX. What are they? It would be fascinating if they were red supergiants or deep red carbon stars, but I find that very unlikely. The orange objects are too orange and too bright compared with the other stars of Holmberg IX to be stars. Besides, no similar population of bright red stars are visible around the outer edges of M81. No, the orange objects are almost certainly distant, and therefore highly reddened, galaxies. So small blue dwarf galaxy Holmberg IX sits superimposed (from our point of view) on a distant galaxy cluster. Fascinating!
I, too, really appreciated the view of Arp's Loop. It is particularly interesting to see how this dust feature looks brownish when seen superimposed on the bright yellow bulge of M81, but the same dust feature looks blue against the blackness of space. And indeed, there are a few suspiciously pink spots inside the blue arc, testifying to the birth of young blue stars inside it.
Ann