Expert: Ed - 8/4/2004

Question
I'm reading about the Milky Way, clusters etc and i came across the term Sag DIG. Can you please tell me what it is?  

Answer
Matt,
I feel bad that I missed your question yesterday.  I was online until about 5 minutes before your question was delivered to my e-mail account.  Sorry I missed you.

Aaaaanyway... Sag DIG is an irregular dwarf galaxy, which from our perspective on Earth appears to be in the constellation Sagittarius.  That's what the "Sag" means, it's just a handy little abbreviation for Sagittarius.  The DIG stands for "dwarf irregular galaxy."

If you're wondering why the DIG is capitalized and the Sag isn't, I'm not exactly sure.  It's just kind of a tradition among astronomers to give constellations short abbreviations, which are not necessary to capitalize or put a period after them.  This is probably because so many constellations have incredibly long, Greek names which are tough to spell.

Sag DIG is located in our local group of galaxies.  This link from Arizona gives some good information about our local group of galaxies.
http://seds.lpl.arizona.edu/messier/more/local.html

If you enjoy that website, I feel obliged to let you know about the folks that run it.  They're awesome, I totally love those guys.  You can find lots of great stuff on their website:
http://seds.lpl.arizona.edu/seds/

I hope that was helpful.  Keep Looking Up!
--Ed