20 December 2016 | WR 134

WR 134

Image credit & copyright: Lionel Mulato | Click image to enlarge

Image Data

  • Location: France
  • Camera: Atik 4000M
  • Optics: Takahashi TSA102
  • Filters: Astrodon 5nn Ha, OIII
  • Exposure: Ha 7 x 20m, OIII 8 x 20m

Wolf Rayet stars are extremely massive and luminous with powerful stellar winds and represent an evolutionary phase of massive stars preceding stellar death. Named after their discoverers Charles Wolf and Georges Rayet who first identified them in 1867, a few hundred of this type are known in our galaxy with populations also uncovered in other galaxies. A small portion of Wolf Rayet stars have an associated nebula, which is either material ejected by the star, general unrelated material in the surrounding ISM that has been swept up into a bubble by the strong stellar winds and there is also a third type that combines characteristics of both.

One example of a star with an associated nebula is WR 134 in the constellation Cygnus. It can be seen in this image to the left of the blue arc, it is the second star from the top of the line of four stars near the centre of the image. The nebula is composed primarily of ionized oxygen (OIII) and it also contains some hydrogen-alpha nebulosity although this is difficult to distinguish from the surrounding background nebulosity, which is ubiquitous in the expansive starfields of Cygnus. This image features a second Wolf Rayet star, WR 135, which is the bright star near the left edge of the image immediately to the left of WR 134.

The ring nebula surrounding WR 134 was discovered in 1971 by David Crampton and is embedded in the giant HII region Sh2-109. However the nebula wasn’t considered to be conclusively associated with WR 134 until later studies. Wolf Rayet ring nebulae were first defined in 1965 with the first three recorded examples being the more well known Crescent Nebula (NGC 6888) and Thor’s Helmet (NGC 2359) and the lesser known Sh2-308. In the following decades, photographic surveys for ring nebulae around Wolf Rayet stars were conducted with many discoveries in the optical as well as more recently at infrared wavelengths.

Located at a distance of 6000 light years, WR 134 and its associated nebula are often the target of amateur astrophotographers. It is also one of a small number of Wolf Rayet nebulae that is possible to be visually observed with the aid of an OIII filter. Despite being known for many decades, WR 134 still presents some mysteries to be unraveled with some research projects being conducted including a pro-am collaboration.

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