View Full Version : Prey of the Milky Way

2002-Feb-22, 01:12 AM
See Prey of the Milky Way (http://www.sciam.com/1998/1098issue/1098laham.html) section of an article in Scientific American.

The SEDS website (http://www.seds.org/messier/more/SagdEg.html) says "This galaxy was immediately recognized as being the nearest known neighbor to our Milky Way."


"In February 1998, a team of astronomers headed by Rosemary Wyse of John Hopkins University found that SagDEG orbits the Milky Way Galaxy in less than one billion years. Because it must have passed the dense central region of our Galaxy at least about ten times, it is surprising that the dwarf has not been disrupted for so far. Astronomers suspect that this fact is an indication for significant amounts of dark matter within this small galaxy, which ties the stars stronger to the galaxy by its gravity."

<font size=-1>[Thanks to JW for suggesting this topic (http://www.nw.uklinux.net/bbs/messages/3757.html)]</font>

The Bad Astronomer
2002-Feb-22, 04:25 AM
I actually talk about the Sagittarius dwarf galaxy in my Bitesize pages (http://www.badastronomy.com/bitesize/invader.html).

2002-Feb-22, 08:23 AM
Thanks BA, I shoulda checked there first.

One small nit--it seems it was discovered by R. Ibata, M. Irwin, and G. Gilmore, but R. Wyse calculated its orbital period.

It seems to be only 80,000 ly away, and the diameter of the Milky Way is 100,000 ly, so it is much closer than the Magellanic Clouds. The reason it was not noticed before is it is partly hidden by the Milky Way (http://www.sciam.com/1998/1098issue/1098lahambox9.html) center--its on the other side of the galaxy. They're about an hour apart in RA.

2002-Feb-22, 10:33 AM
There are more things between the core and the arms than are dreamt in your astronomy...

2002-Feb-22, 01:15 PM
Actually, it looks like it has been disrupted. Several overdensities of stars have been found in the Milky Way's halo that match the metallicity of the stars in the Sagittarius Dwarf galaxy.