by Chris Peterson » Thu Apr 07, 2016 2:22 pm
geckzilla wrote:Chris Peterson wrote:JPL wrote:I would like to see a picture of remote objects like this stripped of Milky Way stars, assuming it's possible to identify foreground stars. After a lifetime of viewing such pictures, it is difficult to escape the notion that space is cluttered with stars. Such a doctored image, if honestly labelled, might help dispel this misleading feeling of clutter, and in a sense convey more truthfully what is (isn't) out there.
Except near the edges of the galaxy, nearly every star in this image is a foreground star. Removing them would be a rather laborious manual task, however, and one complicated by the fact that many of the objects that appear to be stars are actually background galaxies.
The halo of this galaxy likely extends to the edges of the frame, especially the left and right sides and more sparsely at the top and bottom. Separating the three main layers here would indeed be a strenuous exercise, but I think there may be fewer foreground stars than it looks like. IMO, the vast majority of tiny dots in this image are comprised of WLM and distant, blueish background galaxies. Obviously, I can't say for certain, but this view is well away from the plane of the Milky Way and it is also a relatively narrow field of view. I guess what I really want to say is that these dwarf galaxies are often more extended than one might initially think them to be.
Yes, I thought about this and you might well be correct. It's not at all obvious at this scale where the galaxy's halo actually ends, or how compact the galaxy is.
Galaxies can largely be isolated automatically by looking at their profiles. A handful of obvious foreground stars can be removed on the basis of their intensity. But otherwise, this galaxy is too close to easily distinguish its stars from Milky Way stars by any easily measured characteristics. I think we could look at that area of sky in that region and statistically determine how many local stars should be present, however.
[quote="geckzilla"][quote="Chris Peterson"][quote="JPL"]I would like to see a picture of remote objects like this stripped of Milky Way stars, assuming it's possible to identify foreground stars. After a lifetime of viewing such pictures, it is difficult to escape the notion that space is cluttered with stars. Such a doctored image, if honestly labelled, might help dispel this misleading feeling of clutter, and in a sense convey more truthfully what is (isn't) out there.[/quote]
Except near the edges of the galaxy, nearly every star in this image is a foreground star. Removing them would be a rather laborious manual task, however, and one complicated by the fact that many of the objects that appear to be stars are actually background galaxies.[/quote]
The halo of this galaxy likely extends to the edges of the frame, especially the left and right sides and more sparsely at the top and bottom. Separating the three main layers here would indeed be a strenuous exercise, but I think there may be fewer foreground stars than it looks like. IMO, the vast majority of tiny dots in this image are comprised of WLM and distant, blueish background galaxies. Obviously, I can't say for certain, but this view is well away from the plane of the Milky Way and it is also a relatively narrow field of view. I guess what I really want to say is that these dwarf galaxies are often more extended than one might initially think them to be.[/quote]
Yes, I thought about this and you might well be correct. It's not at all obvious at this scale where the galaxy's halo actually ends, or how compact the galaxy is.
Galaxies can largely be isolated automatically by looking at their profiles. A handful of obvious foreground stars can be removed on the basis of their intensity. But otherwise, this galaxy is too close to easily distinguish its stars from Milky Way stars by any easily measured characteristics. I think we could look at that area of sky in that region and statistically determine how many local stars should be present, however.