Thin bands of cloud intersect a series of bright green auroral rays last night. Photo: Bob King
Wow – two decent auroral displays in a week! We haven’t had that around here for a long time. While last night’s lights were in the forecast, they weren’t described as anything more than “isolated active periods”. I think it came as a surprise at how bright and widely seen across the northern U.S. they were. Tonight there’s a chance for more. With early evening skies forecast to be clear for the Duluth, Minn. region, be sure to spend a few minutes outside watching the northern sky for any activity.
New moon happens this Tuesday and on Wednesday the thin crescent returns to the evening sky. Take advantage of the next few moonless nights to explore two star clusters in the constellation Cancer the Crab. One of them, nicknamed the Beehive, is visible to the naked eye from suburban and rural skies as a cloudy patch. The other goes by the simple catalog designation of M67 and requires binoculars or a small telescope to see.
To find out featured star clusters, get your bearings using Orion and the bright Winter Triangle. The bright pair of stars Castor and Pollux are to the Triangle's upper left. Two binocular fields below them, you'll bump into the Beehive, then drop straight below to arrive at M67. Created with Stellarium
M44 has been known for centuries. The ancient Greeks and Romans saw the thatch of stars as a manger filled with hay from which a pair of donkeys ate. We know it as M44 or the Beehive, an open cluster containing hundreds of stars located 582 light years from Earth. While you probably won’t be able to distinguish individual stars with your eye, binoculars easily reveal the Beehive’s buzz of tiny suns. Take a look. You might be surprised at how effortlessly the ‘fuzz’ resolves into stars. Galileo pointed his little telescope at the cluster back in 1609 and counted 40. How many can you see?
The Beehive Cluster is flanked by two stars that represent the donkeys at the manger. Photo: Bob King
M67, though fainter than M44 is no less fascinating. Most clusters like the Beehive were born from clouds of gas and dust in the flat disk of the Milky Way galaxy. Standing apart from the crowd, M67 is situated well above the galactic plane some 2,800 light years from Earth.
Clusters within the disk eventually get pulled apart by gravitational interactions with other gas clouds and passing stars. M67, far from the hubbub of the disk, has remained intact for over 4 billion years, an exceptionally long life for a star cluster. A typical cluster lifetime is around 10 million years.
The cluster’s age and chemical makeup of its stars are nearly the same as that of our own sun – about 4 billion years.
Recently, astronomers identified a nearly identical twin of the sun within the cluster. There’s even speculation that because of the similarities, the sun may once have been a full-fledged member of M67 that somehow escaped the mother cluster to live the single life with its pals in the galaxy’s disk. Could it have strayed during one of M67′s “brief” orbital passes through the thicket of the Milky Way?
The stars in the open star cluster M67 in Cancer have a composition nearly the same as the sun. Credit: Bob Franke
While most astronomers think the chances are small that the sun originated in M67, we know it must have been born within a similar cluster of stars. That’s why they continue to study this binocular object in Cancer to learn more about what the sun’s birthplace may have been like.
You can learn more about M67 and its solar connections in an excellent article in the March 2012 issue of Sky and Telescope magazine.
Through binoculars the cluster is hazy patch dotted with stars; a telescope completely resolves it into many stars – a rich sight. Look it up and imagine this place as a womb of the sun’s birth.
Author : astrobob Read Full Article