Archive for Open cluster

Getting Sirius about “The Dog star”

Posted in Uncategorized with tags , , , , , , , , on February 21, 2009 by Andrew

It has been a while since I have posted a article on a star and I thought now would be a good time.While I had the scope out the other night (finally! ūüôā ) I decided to get a shot of Sirius a.k.a the Dog star (which is Orion the hunters larger dog) .Sirius is best viewed during the winter months thru early spring in the northern hemisphere.It is a blue-white star that packs a Sirius bite….hahahahaha!!.Sorry,I couldn’t help myself!!!.Located in the constellation Canis Major,Sirius is only 8.6 light years distant.Being twice as¬† massive than our own sun,Sirius is also 20 times brighter at a visual mag of -1.46 and almost twice as hot at 9800 K,hence it’s blue-white color.
Sirius is part of a large asterism,which is called the Winter Triangle, along with two other stars… Betelgeuse in Orion and Procyon in Orions smaller dog,which is called Canis Minor.
Only to be seen with a telescope,Sirius also has a companion star which is called Sirius B *see image below*,a small white dwarf, and is¬† nearly 10,000 times fainter.This does not mean that Sirius B is cooler than Sirius A.Sirius B, in fact is much hotter at approximately 23,000k and is thought to have been slightly larger than Sirius A¬†at one time in it’s life.This leads me to believe that Sirius B is the older of the two?!.

Image was at prime focus¬†taken with a 10″ Meade LXD75sn and Pentax istDs DSLR.Skies were clear and the temp was in the mid teens F.

Information credit: Stars

Image credit: Andrew


NGC 869,NGC 884 (The Double Cluster)

Posted in Uncategorized with tags , , , , , , on September 22, 2008 by Andrew

One of the other naked eye¬†objects that I took images of is of the Double cluster.As I mentioned in my last post,this cluster was easily seen without optical aide which is one of the¬†objects that I can’t see naked eye,¬†when observing in the middle of town.This is obviously due to the fact that this cluster is located to my north which happens to be directly over the middle of town.So,all I see in that direction are a few brighter stars shrouded by the pinkish glow of street lights.

I had written a post previously about the Double cluster including a image and thought that it looked pretty nice with what I thought at the time included lots of stars.Heh,I decided to compare the two images and to my surprise,the most recent shot has probably 3 times as many stars as the old one.Dark skies dark skies dark skies!!!.That is what it is all about.The difference is truely amazing!!!.

The famous double cluster in Perseus was known in antique times (probably even pre-historically), and first cataloged by the Greek astronomer Hipparcos.
Both clusters are situated in Perseus and are only a few hundred light-years appart, at a distance of over 7000 light years.
At a visual mag of +4.3,NGC 869 is approaching us at 22 km per second.
At a visual mag of +4.4,NGC 884 is also approaching us at a slightly slower 21 km per second.


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