by Ann » Wed May 25, 2016 5:04 am
Beautiful image.
Since APOD Robot had helpfully informed us that NGC 5078 would be in today's picture, I had already checked out some facts about it and decided to compare it with M104, the Sombrero galaxy.
M104. Photo: NASA/ESA and The Hubble Heritage Team (STScI/AURA)
NGC 5078 and M104 are, to a degree, similar in type. Both are edge-on spiral galaxies of Hubble type Sa, with large bulges and tightly wound spiral arms. But they are very different, too. Fascinatingly, the Sombrero is both redder and bluer than NGC 5078. It is bluer in that its B-V index is bluer than that of NGC 5078, 0.980 versus 1.040, but it is redder in that its U-B index is redder than that of NGC 5078, 0.530 versus 0.360. And M 104 is
much fainter than NGC 5078 in far infrared light. Even though M104 is about three magnitudes brighter in visual light in our skies than NGC 5078, the latter is more than half a magnitude brighter than M104 is far infrared light even at its farther distance from us.
Conclusion? M104 is a staid, settled galaxy, with a well-ordered dust lane where nothing much is happening. NGC 5078 is a smaller galaxy, far less well-behaved and much dustier, which reddens the visual light from this galaxy. But there is star formation going on in NGC 5078, which by all accounts is missing in M104.
In today's APOD, we can actually see the pink nebulas characteristic of star formation in the outer arms of NGC 5101, the large face-on galaxy. And I think we can see hints of star formation in the upper parts of the dust lane in NGC 5078.
Fascinating image! Thanks!
Ann
Beautiful image.
Since APOD Robot had helpfully informed us that NGC 5078 would be in today's picture, I had already checked out some facts about it and decided to compare it with M104, the Sombrero galaxy.
[float=left][img2]http://tinyurl.com/zypo2ef[/img2][c][size=75]M104. Photo: NASA/ESA and The Hubble Heritage Team (STScI/AURA)[/size][/c][/float] NGC 5078 and M104 are, to a degree, similar in type. Both are edge-on spiral galaxies of Hubble type Sa, with large bulges and tightly wound spiral arms. But they are very different, too. Fascinatingly, the Sombrero is both redder and bluer than NGC 5078. It is bluer in that its B-V index is bluer than that of NGC 5078, 0.980 versus 1.040, but it is redder in that its U-B index is redder than that of NGC 5078, 0.530 versus 0.360. And M 104 is [i]much[/i] fainter than NGC 5078 in far infrared light. Even though M104 is about three magnitudes brighter in visual light in our skies than NGC 5078, the latter is more than half a magnitude brighter than M104 is far infrared light even at its farther distance from us.
Conclusion? M104 is a staid, settled galaxy, with a well-ordered dust lane where nothing much is happening. NGC 5078 is a smaller galaxy, far less well-behaved and much dustier, which reddens the visual light from this galaxy. But there is star formation going on in NGC 5078, which by all accounts is missing in M104.
In today's APOD, we can actually see the pink nebulas characteristic of star formation in the outer arms of NGC 5101, the large face-on galaxy. And I think we can see hints of star formation in the upper parts of the dust lane in NGC 5078.
Fascinating image! Thanks!
Ann