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Messier 67
Oct. 3rd, 2010 07:46 amLet’s leave the 40-50 light year range for a day and plunge much farther out -- 2700 light years out, more or less, to a star cluster located in Cancer. This is Messier 67 or M67, an “open cluster” -- a group of stars that were all formed about the same time and are bound together for the time being by gravity. (Eventually, they’ll drift apart and move to different areas of the galaxy. Still, M67 will probably continue to exist as a cluster for billions of years.)
M67 is probably about 4 billion years old, meaning it’s made up of stars -- 500 or so -- that are a little younger than Sol, but not more than a few hundred million years younger. (It may be as old as 5 billion.) And among these 500 stars are more than 100 that are similar to Sol!
Astronomers have studied M67 closely because it has taught them a lot about stellar evolution. An SF writer could find this a great backdrop for a novel, because there are so many sunlike stars so closely packed together.
A few back-of-the-envelope calculations will show what I mean. M67 is roughly spherical in shape and is about 12 light years across. That gives it a volume of about 900 cubic light years. If there are 100 sunlike stars in the cluster, that comes to about 1 every 9 cubic light years, or three every 27 cubic light years. Imagine a cube three light years on each side; on average, such a cube in M67 would contain three sunlike stars! And there would also be around 12 other stars of varying classes, probably none above F (for some reason, nearly all stars in M67 are F or smaller). By comparison, such a cube centred on Sol wouldn’t even contain our closest stellar neighbours.
Imagine if a few million years ago, the Precursors/Forerunners/Vanished Ones, who found Earthlike planets congenial, terraformed all the usable planets in this cluster, then disappeared for whatever reason… there would be lots of real estate for the next species (us) to come along. Or maybe we’re not the only contemporary species who want to move in!
M67 is probably about 4 billion years old, meaning it’s made up of stars -- 500 or so -- that are a little younger than Sol, but not more than a few hundred million years younger. (It may be as old as 5 billion.) And among these 500 stars are more than 100 that are similar to Sol!
Astronomers have studied M67 closely because it has taught them a lot about stellar evolution. An SF writer could find this a great backdrop for a novel, because there are so many sunlike stars so closely packed together.
A few back-of-the-envelope calculations will show what I mean. M67 is roughly spherical in shape and is about 12 light years across. That gives it a volume of about 900 cubic light years. If there are 100 sunlike stars in the cluster, that comes to about 1 every 9 cubic light years, or three every 27 cubic light years. Imagine a cube three light years on each side; on average, such a cube in M67 would contain three sunlike stars! And there would also be around 12 other stars of varying classes, probably none above F (for some reason, nearly all stars in M67 are F or smaller). By comparison, such a cube centred on Sol wouldn’t even contain our closest stellar neighbours.
Imagine if a few million years ago, the Precursors/Forerunners/Vanished Ones, who found Earthlike planets congenial, terraformed all the usable planets in this cluster, then disappeared for whatever reason… there would be lots of real estate for the next species (us) to come along. Or maybe we’re not the only contemporary species who want to move in!