2006-11-08 00:31:58 · 5 answers · asked by goring 6 in Science & Mathematics ➔ Astronomy & Space
Small "dwarf spheroidal" galaxies tend to be the least dense. They are hard to detect because they have low surface brightness and barely stand out against the residual sky glow (even from orbit). They are the least dense because they have survived from the earliest era of small galaxy formation, and have not merged with any other galaxies.
There are stars in intergalactic space, not associated with any galaxy, that have been flung out of galaxies during collisions. These are darn near impossible to detect.
Low density galaxies are so hard to detect, and probably merge continuously into a population of stars not in galaxies, that to pick one out as the lowest density would pretty much be a matter of definition, i.e. how small can a galaxy be and still be called a galaxy; does it need to be bound, etc.
I can forsee some future meeting of the IAU attacked by the public over this issue like the recent furor over Pluto.
Galaxies are really accumulations of Dark Matter first, and have gas and stars as a secondary phenomenon. It is speculated that there may be many more Dark Matter accumulations, that is to say galaxies with essentially no stars in them, than there are galaxies.
2006-11-08 03:36:01 · answer #1 · answered by cosmo 7 · 2⤊ 0⤋
While we aren't likely to be able to count the stars in another galaxy, spectral analysis gives an idea of the relative elemental abundances and this helps handicap the overall luminosity observed to make reasonable estimates of stellar density.
Looking for the least dense, rather than most dense, galaxy presents a particular problem: finding it. Unless it happened to be the most adjacent galaxy, it could in fact be too dim to be detectable against the background of more distant, but brighter galaxies and through the intervening stars and dust of our own galaxy. Perhaps you meant not the least of all?
2006-11-08 01:10:17 · answer #2 · answered by ? 5 · 0⤊ 0⤋
We don't know the answer to something like that. There are a hundred billion galaxies in the observable universe, and we don't know the volume or number of stars in most of them.
2006-11-08 00:37:12 · answer #3 · answered by DavidK93 7 · 0⤊ 0⤋
I don't know but there is some galaxy that is passing by milky way It is called Magellan it is very small but I'm not sure if it is the smallest
2006-11-08 06:58:00 · answer #4 · answered by Anonymous · 0⤊ 0⤋
If someone actually answers this, they are either an alien or lying. No one knows this becuase there are so many galaxies that no one has even seen.
2006-11-08 00:36:15 · answer #5 · answered by Anonymous · 0⤊ 0⤋