Dear all, I propose this time a picture of a field around Alpha Centauri that will be a surprise for many of you. In fact the fascinating object at the right of Alpha Centauri is a very little imaged planetary nebula, Hen 2-111, that is usually known to be a bright peanut shaped PN with a size of only 29 x 15 arcseconds. However, its most visually striking aspect is a faint giant ionized halo that spans 10 x 5 arcminutes! This extreme structure was discovered by B. Louise Webster in 1978 in deep photographic plates taken with the (at the time) Anglo-Australian Observatory. At an estimated distance of 7800 light years, the entire nebula spans approximately 23 light years! The halo is actually a rare bipolar outflow and the other notable planetary nebula known to exhibit this unique feature is the northern hemisphere nebula KjPn 8 in Cassiopeia.
The link (recommended the original resolution “O”):
This feature is so little known that in fact I was not able to find any other image in the net revealing the halo apart few B&W images on professional literature. If you are aware of other deep images it would be interesting to compare the view.
To the right of Hen 2-111 is the attractive pairing of the open clusters NGC 5617 and Pismis 19. NGC 5617 is the larger and younger of the two and despite its apparent youthful appearance, it is actually an intermediate age cluster with an estimated age of 80 million years. Contrastingly, the smaller rich condensed cluster Pismis 19 appears much older than NGC 5617 and indeed its golden ancient light betrays its great age of 800 million years! It is at a similar distance to Hen 2-111 of about 7800 light years whereas NGC 5617 is much nearer at 5000 light years. However, it is subject to severe reddening due to interstellar dust between us and the cluster and would shine more brightly if this dust was less prevalent. Also barely visible in the glare of Alpha Centauri is a round broken roughly circular shell, which can be seen to the north of the halfway point between Alpha Centauri and Hen 2-111. This is the supernova remnant G315.4-0.3, which was discovered in a radio continuum survey by Anne Green in 1974 and identified as a supernova remnant in 1975. However, its extremely dim optical shell was discovered recently in 2011 in a search for new supernova remnants in SuperCOSMOS Ha Survey (SHS) images by Milorad Stupar and Quentin Parker.
I hope you will enjoy the view