DEEP SKY
  Gavin James
  07808 480621
  gavin@gjmultimedia.co.uk
 
Astronomy Deep Sky     << previous next >>
 
M35 & NGC 2158

The objects, M35 (NGC 2168) and NGC 2158 are open clusters and are both seen in the constellation of Gemini, thought they are not physically related. An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age.

M35 is the only Messier object in Gemini and consists of several hundred stars, of which 120 are brighter than magnitude 13. The age of M35 is about 110 million years with the hottest main sequence stars in the cluster having a spectral classification B3. M35 also contains more evolved stars, including several orange and yellow giants. The cluster is approaching us at 5 km/s. M35 was first discovered in 1745 by a Swiss astronomer called Jean-Philippe Loys de Cheseaux, but John Bevis, an English astronomer, found the cluster independently before 1750. NGC 2158 was discovered by William Herschel on November 16, 1784 and catalogued as H VI.17.

You can locate M35 in the night sky by drawing a line from Betelgeuse in Orion to Pollux in Gemini and find Alhena, Gamma Geminorum, the brightest star along this imaginary line and the third brightest star in Gemini, after Pollux and Castor. NGC 2158  lies directly southwest of M35 and is ten times older, four times more distant and more compact. NGC 2158's bright blue stars have already lived and died, leaving the cluster light to be dominated by older and yellower stars.
Research Assistant: Harriet Place

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M35 & NGC 2158
M35 / NGC 2168 & NGC 2158
Open Clusters
Gemini
M35: 2,800 ly
NGC 2158:11,000 ly
M35: 5.3
NGC 2158: 8.6
M35: 35 arcmin
NGC 2158: 8 arcmin
M35: 29 ly
NGC 2158: 26 ly
M35: 1745, Philippe Loys de Cheseaux
NGC 2158: 1784, William Herschel
January
06h 09m 59s
+24º 19’ 38”
Altair Astro 102 & 0.79x Reducer
3 nights, December 2016 & January 2017
L = 24 x 600s
RGB = 12 x 600s each
10 hours

 

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