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Popular Astronomy

May 2017

I received two images and two sketches this month, from three section members.

Paul Brierley of Macclesfield imaged globular cluster M3 in the constellation of Canes Venatici (left) using an Altair Astro 115mm EDT refractor and Canon 1000D DSLR.  M3 has been studied by professional astronomers for over a century.  In 1913 American astronomer S.I Bailey began to identify variable stars within M13, and well over 200 are now known, around half being RR Lyrae type. 

Generally globular clusters are found to be metal poor;  M3 is relatively metal rich for a globular but relative to our sun it is still quite poor in elements heavier than hydrogen and helium however, at about 4%.the solar abundance.

David Davies of Cambridge used an APM 107mm triplet APO refractor and QSI 583 camera plus red, green and blue filters to capture this image (right) of Markarian's Chain, a string of galaxies to be found in the constellation of Virgo.

The pair of galaxies just below left of centre are NGC4435 (uppermost) and below it NGC4438.  The oval galaxies to the right of these are, first, M86, and to its right M84. To the upper left of NGC4438 are a fainter pair:  NGC4461 and the smaller NGC4458 above it.  Toward the top left is NGC4473, and in the top left corner another pair;  NGC4477 and the smaller NGC4479 just below and to the left.

Michael Kinns of Eastry employed an Orion Optics (UK) 200mm f6 Newtonian reflector at x150 and x100 respectively to sketch M102 (below left) and NGC5907 (below right);  both galaxies in the constellation of Draco. M102 is a Messier catalogue item that was once thought to have been a duplicate entry for M101, but many sources identify it as this galaxy, also known as NGC5866 or the Spindle galaxy.  High resolution professional images show the galaxy to have a disc of dust;  not common for a lenticular galaxy;  since it is almost exactly edge-on however it is possible that it is really a spiral.  NGC5907 is also an edge-on galaxy, sometimes known as the Splinter galaxy.  Professional images show streams of material around it, possibly evidence of a gravitational encounter long ago.

      

Dave Finnigan

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