View Full Version : Appearance of a galaxy changes dramatically with viewing col

2001-Nov-05, 07:50 PM

2001-Nov-05, 07:55 PM
I may be bit slow, so forgive me for asking.

How do this go "against the mainstream?"

The Curtmudgeon
2001-Nov-05, 09:30 PM
On 2001-11-05 14:55, Wiley wrote:
I may be bit slow, so forgive me for asking.

How do this go "against the mainstream?"

I think Mifletz thinks that this is his Home folder. /phpBB/images/smiles/icon_smile.gif

The (probably just as well) Curtmudgeon

Spaceman Spiff
2001-Nov-06, 01:29 AM
Yes, that's right, and for completely understood reasons. UV light is emitted by massive stars only. These don't live long and so don't wander far from the environs of their birthplace - giant molecular clouds. In spiral galaxies these are found in the spiral arms. So (restframe) UV images of spiral galaxies look really clumpy.

I don't know what Mifletz is up to here, but I suspect he doesn't like the observed fact that galaxies evolve in their appearance and stellar populations with increasing redshift (and so lookback time). While these initially were tentative conclusions based on the first HST images of high redshift galaxies at visible wavelengths (so looking at restframe UV light), this evolution holds even when we look at the restframe visible light from these distant galaxies at infrared wavelengths. They really are different. On top of that, we also see a greater fraction of galaxies merging or interacting at increasing redshift, just as expected in a denser, immature universe.

The Hubble tuning fork diagram of galaxy morphology only holds for the relatively recent (and nearby) universe.