15 October 2016 | NGC 300

NGC 300

Credit: CHART32 | Processing: Johannes Schedler | Click image to enlarge

Image Data

  • Location: Chile
  • Date taken: Robotic image aquisition July-August 2013
  • Camera: FLI Proline 16803
  • Filters: Baader Ha-LRGB
  • Optics: 80cm f/7 Astrooptik Keller corrected cassegrain
  • Exposure time: Ha 15x40m / L 20x20m / R 10x20m / G 10x20m / B 10x20m (total 28 hours)

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NGC 300 is a dazzling spiral galaxy, which is one of the most prominent members of the Sculptor Group of galaxies. It is one of the most well known galaxies in the southern constellation of Sculptor and is easily observable by amateur astronomers in telescopes.

However deep images such as this one reveal the full majesty of its spiral arms, which contain a retinue of blazing brilliant open clusters and OB associations. This image also includes exposures taken through a hydrogen-alpha (Ha) filter, which isolates the specific narrow light of hydrogen, thereby revealing its amazing collection of nebulae, most of which aren’t visible in regular LRGB images. This galaxy is sometimes regarded as the southern equivalent of the northern galaxy M33, which also has many spiral arms with a multitude of HII regions.

The exquisite detail and resolved stars is partly due to its very nearby (on cosmic terms) distance of 6 million light years. The Sculptor group is the closest galaxy group to the Local Group. Another contributing factor to its high apparent observed brightness is low galactic absorption, which means that its light travels through a lower amount of dust in our Milky Way galaxy to reach Earth. Other galaxies that suffer from high dust absorption appear less bright but still have a high intrinsic luminosity.

NGC 300 is of great interest to professional astronomers and has been studied extensively. There have been many observations with x-ray observatories starting with ROSAT in 1991 and more recently with Chandra. A large population of x-ray sources have been uncovered with some of them coinciding with optical supernova remnants and HII regions. The most well known one is NGC 300 X-1, an exotic black hole x-ray binary system of a Wolf Rayet star and a black hole! This is only the second Wolf Rayet black hole binary system that has been discovered in another galaxy, the other being IC 10 X-1 in the northern galaxy IC 10.

Another interesting object in NGC 300 is the “supernova impostor” SN 2010da, which was discovered by the amateur astronomer Berto Monard and has now been identified as a high mass x-ray binary system and the original 2010 supernova outburst an intermediate luminosity optical transient.

The presence of multiple HII regions signifies a high star formation rate, which is in contrast to the old age of more than 6 billion years for the majority of the stellar population. Recent massive star formation has been taking place for tens of millions of years as evidenced by the presence of a significant population of Wolf Rayet stars. In addition to this, more than 100 OB associations have been discovered. OB associations are small groups of young massive stars that formed together at the same time from the same molecular cloud.

Originally discovered by the Scottish astronomer James Dunlop from Australia in 1826, this fascinating galaxy is still receiving lots of attention from astronomers and has helped studies of galaxy formation and structure. It is now known to have a size of approximately 50,000 light years making it half the size of the Milky Way. Representing stellar death, many planetary nebulae and supernova remnants have also been identified in NGC 300.

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