Saturday, July 31, 2010

Baby Stars

Click on Image for a larger view
On the right side of the above picture is the famous "Double Cluster", one of the all-time favorites for amateur astronomers.  If you know where to look in the constellation Perseus, its a hazy patch of light to your unaided eyes, and in a pair of binoculars each cluster is resolved into a tight knot of stars against a starry backdrop.  For small telescopes, it is one of the finest clusters in the heavens, with many stars of contrasting colors.  Its existence was noted by Hipparchus and Ptolemy around 150 BC, but to them it was a nebula and its true nature had to wait until the invention of the telescope.

At the upper left of the image is another cluster of stars called Stock 2, but these are much more open, spread out and not as bright.  Through a pair of binoculars, Stock 2 looks like a headless stick man.  With your imagination running wild, you can even imagine one of his up raised arms holding a leash of curving stars that go down to the double "puffs" of a poodle.  Binoculars do not show as many stars as this photograph so seeing the stick man and the poodle will require you to go out and look for yourself.  To see it look about 15 degrees above the Northeast horizon soon after it gets dark.  By Midnight, it is about 25 degrees high.

Click on Image for a larger view
The Double Star Cluster look like they are neighbors, but the distance to this great swarm of stars is not identical.  The lower cluster, also known as NGC 884, is further away at 7600 light years. The upper cluster, NGC 889, is 6800 light years. 884 is also the older of the two.  However, when we consider the age of stars, these clusters are one of the youngest in our Milky Way galaxy, 3.2 million years old for 889 and 5.6 million years old for 889.  Millions of years may seem like a long time for us humans, but in astronomical terms, its very young.  Our own Sun is about 2.5 billion years old.  At the other extreme, are globular clusters, which are more than 10 billion years old.

Another interesting fact about these "baby stars".  If you were on a planet orbiting one of these stars and you looked toward our Sun, you would be hard pressed to see it.  This is because the brightest stars in these clusters are all great blazing supergiants of amazing brilliance compared to the Sun.  The brightest stars are 60,000 times brighter then the Sun.  Not only that, they are unimaginably large.  Placing of these supergiant stars in place of the Sun, it's diameter would go out beyound Earth's orbit.  Of interest is the presence of M-type red supergiant stars.  Some of these are located in the image below.
 Click on the Image for a larger view
One more interesting fact.  The Perseid meteor shower, which this year peaks during the evening of Aug 12 and morning hours of Aug 13, is near the radiant point of this shower. 
n other words, these "shooting stars" appear to come from this part of the night sky.

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