Tuesday, November 4, 2014

Young and old clusters. And carbon star.

Messier 38 - that is the name of open star cluster in the Auriga constellation. Together with nearby M36 and M37 they are grouped at a distance of about 4200 light years away from Earth. The cluster birightest stars form a pattern resembling Greek letter pi. The age of the cluster is intermediate (about 220 million years). It's brightest member is spectral type G0 yellow giant with apparent magnitude 7.9mag. This star is 900 times more luminous than Sun.

Below M38 there is another small open cluster - NGC1907. About twice as old as M38, but contains only around 30 stars, and is placed in the same distance - about 4500 light years.
And there is even more - Czernik 21 open star cluster. Actually even if you know where it is you probably won't notice that smudge of stars. I have marked the clusters in the picture, that is how Czernik 21 has been described by Lew Gramer and Michael Carnes while observed with 17.5" telescope:
"Heading back up to M38 and then NW just 20', we encounter a third OC in this little Winter tableau, the very faint Czernik 21. This is a smudge of unresolved stars, only just visible to averted vision half way from M38 to a bright, pretty pair of stars mag 8, colored orange and yellow (HD35202 and HD35089). The smudge was quite small, making it fairly distinct at 220x in spite of its faintness." 
Czernik 21 open cluster is the oldest among these three at the picture - it is over one billion years old.

One thing caught my eye - deep red star in the picture. I was wondering if it is a post processing fault or an artifact, but it turned out to be carbon star V* OQ Aur. Carbon stars are cold, red giants that radiates most of its energy as infrared light.

Clear skies!

Wobbling Moon

One may think the Moon is faced towards us always the same side. Well, yes and no :) Actually the Moon oscillates a little during its orbital motion, so experienced observers can peek a few degrees to the dark side of the Moon. This phenomenon is called libration.
You may compare prominent crater Herschel pictures made this year by me in different seasons:

Herschel - 03.11.2014, SCT11", ASI120MM

Herschel - 14.03.2014, newton 6", ASI120MM
The difference in the view angle is quite dramatic.

Clear skies!