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Popular Astronomy

March 2015

This month, four section members sent in a total of 9 observations comprising 3 drawings and 6 images.

Mike Wood, observing from Debenham, used his 180mm Takahashi Mewlon Dall - Kirkham reflector to observe and draw open cluster M47, (right), which is in the constellation of Puppis.  At about 1600 light years from Earth, there are around 50 stars in M47;  the estimated age of this cluster is 78 million years.  The brightest star is magnitude 5.7. 

This was for many years a "lost" Messier object;  in 1959 T.F.Morris, a Canadian astronomer changed the signs of Messier's M47 coordinates and found that the new coordinates exactly matched those of open cluster NGC2422!

M47 is not far in the sky from M46, another open cluster which is both much older and distant.                                                                  

                                 The sketch on the top left is planetary nebula NGC2440, and below it NGC2438, another planetary nebula.  Both are in the constellation of Puppis.  NGC2440 is condsidered to be about 4000 light years from the Earth, and has an apparent magnitude of 9.4.  The central star is designated HP62166, and with a surface temperature of about 200,000 K is one of the hottest known white dwarf stars.                                                                                                                               

NGC2438 is a little closer to us at 3000 light years, and looks to be within open cluster M46, but does not share the cluster's radial velocity.  The white dwarf at the centre of NGC2438 is magnitude 17.7, and its surface temperatue is about 75.000 oK. 

Mike used a 20'' Dobsonian telescope and a magnification of 311x to observe the two planetary nebulae.                                                                                                                                                                                                                                             Steve Norrie of Fife submitted the image on the right during the reporting period.  It shows the Leo Triplet;  three galaxies in Leo about 35 million light years from the Earth.  Also known as the M66 group, M66 is at the bottom left of the triangle formed by the three galaxies, with M65 at the bottom right and NGC3628 at the apex of the triangle.  They have apparent magnitudes of 9.7, 10.3 and 9.3 respectively.  Steve used a Skywatcher EDR 80 refractor, and an astro - modified Canon 600 D DSLR.

Mark Beveridge, observing from Aberdeen, sent in two images of spiral galaxies in the constellation of Canes Venatici.  On the left, below, is M94; of interest because it has two ring structures, both are sites of new star formation.  It is about 16 million light years from the Earth with an apparent magnitude of 8.9. 

Below right is M63, also known as the Sunflower galaxy.  This magnitude 9.3 galaxy is about 37 million light years away from us.    

          Ian Papworth of Bedfordshire used a Celestron Nexstar 6SE f6.3 telescope and a ZWO ASI 120mm mono camera plus colour filters to produce images of M63, described above (below, left); M81, also known as Bode's galaxy, in the constellation of Ursa Major, (below right) and M13, a globular cluster in the constellation of Hercules (bottom).  With an apparent magnitude of 6.9 M81 is about 12 million light years from the Earth, and has an active nulceus, which has a 70 million solar mass black hole at its centre.  M13 is about 22 million light years from the Earth, has an apparent magnitude of 5.8 and contains about 300,000 stars.  

                                                                       

                                                                                        

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