Image Credit: NASA, ESA, Hubble Heritage Team (STScI/AURA), and W. P. Blair (JHU) et al.
M83 is one of the closest and brightest spiral galaxies on the sky. Visible with binoculars in the constellation of Hydra, majestic spiral arms have prompted its nickname as the Southern Pinwheel. Although discovered 250 years ago, only much later was it appreciated that M83 was not a nearby gas cloud, but a barred spiral galaxy much like our own Milky Way Galaxy. M83, pictured above by the Hubble Space Telescope in a recently released image, is a prominent member of a group of galaxies that includes Centaurus A and NGC 5253, all of which lie about 15 million light years distant. Several bright supernova explosions have been recorded in M83. An intriguing double circumnuclear ring has been discovered at the center of of M83.
Seven Sisters (Messier object 45 or M45), is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. The most famous star cluster on the sky, the bright stars of the Pleiades can be seen without binoculars from even the depths of a light-polluted city.
Under ideal observing conditions, some hint of nebulosity may be seen around the cluster, and this shows up in long-exposure photographs. It is areflection nebula, caused by dust reflecting the blue light of the hot, young stars. It was formerly thought that the dust was left over from the formation of the cluster, but at the age of about 100 million years generally accepted for the cluster, almost all the dust originally present would have been dispersed by radiation pressure. Instead, it seems that the cluster is simply passing through a particularly dusty region of the interstellar medium. Studies show that the dust responsible for the nebulosity is not uniformly distributed, but is concentrated mainly in two layers along the line of sight to the cluster. These layers may have been formed by deceleration due to radiation pressure as the dust has moved towards the stars.
Imaging telescopes or lenses: Takahashi FSQ Fluorite
Imaging cameras: SBIG STL-11000M
Mounts: Paramount GT-1100S
Dates: Oct. 2, 2013
4×300″ bin 1×1
RGB filters: 3×300″ bin 1×1
Integration: 0.6 hours
Autor: Giulio Ercolani
AstroPhotography of the day by SPONLI
28 January 2014
We select the best works of amateur astrophotographers with details of equipment, shooting processing etc.