M4 Globular Cluster in Scorpius

M4 is one of the nearest globular clusters in the sky; its distance is perhaps only about 7,200 light years. M4 can be detected by the naked eye under very dark skies (1.3 degrees west of Antares, visual brightness 5.6 mag), and is prominent with the slightest optical aid.

As a remarkable detail, M4 displays a central "bar" structure, well visible in my image, roughly from slightly above left to below right. It would be one of the most splendid globulars in the sky if it were not obscured by heavy clouds of dark interstellar matter. Its angular diameter is more than 26 minutes of arc, nearly that of the full Moon; this corresponds to a linear diameter of about 58 light years. M4 recedes at 65 km/sec and contains at least 43 known variables.

In August 1995, the Hubble Space Telescope has photographed white dwarf stars in M4, which are among the oldest stars in our Milky Way Galaxy.

I take this image through a Celestron refractor 102mm f/5 on Pixcel 237 CCD. Image is composite of six 20-second unguided exposures (average combine in CCDSoft v5).

 

 

 

 


(C) Copyright 1996 - 2017 by Andjelko Glivar. All rights reserved. This material may not be published in any form without permission.

 

 


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