Popular Astronomy

September 2016

As you might expect, there was an increase in section activity in September, as weather conditions slowly improved and nights became longer.  Four members sent in between them fifteen images and two drawings of deep sky objects.

Steve Norrie, observing from Fife, produced thirteen of the fifteen images.  Below, clockwise from the left, is NGC7635, the "bubble" emission nebula in the constellation of Cassiopeia, IC5146, the "cocoon" emision nebula in Cygnus, IC1805, the "heart" emission nebula in Cassiopeia, and M33 spiral galaxy in Triangulum.  M33's spiral arms are very loosly wound with low surface brightness, and for visual observers is probably best seen with binoculars.                                                                                                                      



 The next four images are of M101, the "pinwheel" face -on spiral galaxy in the constellation of Ursa Major, NGC40 planetary nebula in Cepheus (aka the "bow - tie" nebula and Caldwell 2), NGC281, the "pacman" emission nebula in Cassiopeia and NGC6960, a part of the "veil" supernova remnant in Cygnus.  NGC281 includes the open cluster IC1590, and contains several Bok globules, where new star formation is probably occuring due to the gravitational collapse of cosmic dust and gas.




Below are images of NGC6992, another part of the "veil" supernova remnant in Cygnus, a second image of M33 in Triangulum, NGC7023 reflection nebula in Cepheus and NGC7331, a spiral galaxy in Pegasus.  This image also contains a group of galaxies to the lower left known as "Stephan's quintet".  NGC7331 itself is the largest member of a five - galaxy group, the smaller members are sometimes called the "fleas".                                                                                                                                                                                                                        



Steve's final image this month is NGC6888, the "crescent" emission nebula in the constellation of Cygnus (right).  About 5000 light years from the Earth, the nebula is being formed by the collision between slow moving material ejected from Wolf - Rayet star WR 136 when it was in its red giant phase and the faster current stellar wind.  The  collision shock - wave gives rise to temperatures sufficient to produce X rays and ionise the gas.  Steve used an ES 127 APO refractor at focal ratios of f5 and also f 7.5 and an Atik 490EX colour camera.                             



David Davies, observing from Cambridge,  imaged a part of the "veil" nebula supernova remnant in Cygnus known as "Pickering's triangle" (below right).  David employed a 200mm Richey Chretien telescope at f5.6 with a QSI583 camera and red, blue and green filters.


Ian Papworth, SPA membership secretary, sent in tis image of NGC6826 (below), the "blinking" planetary nebula in the constellation of Cygnus;  so called because in the eyepiece it is best viewed with averted vision, and tends not to be seen when looked at directly as the brightness of the central star overwhelms the nebula.                               



Michael Kinns sent in two drawings of globular clusters.  Below left is M2 in the constellation of Aquarius, and to the right is M71 in Sagitta. M71 was thought to be an open cluster until quite recently (1970's)  due to several factors including lack of a dense core, and an age of around 10 billion years (young for a globular).  It's stars contain more metals than usual for globulars, and M71 lacks the RR Lyrae variable stars found in most globulars.


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