Saturday, May 29, 2021

Talking About Sharpless 2-115

Sharpless 2-115 (abbreviated to Sh2-115, and also known as LBN 357 and Avedisova 1110) is an emission nebula and an H II region, located at a distance of around 7,500 light years in the constellation of Cygnus.

The large oval shaped H II region is dissected in a northwest-southeast orientation by a dark lane. The eastern region dominates a small open star cluster known as Berkeley 90. In the western region the field is dominated by the presence of a variable star known as V2015 Cygnus, but this is a nearby foreground source that is not associated with the region.

The mass of the region has been estimated at 4,400 solar masses, while its physical size is over 100 light years across. Significant star formation activity has been identified within Sh2-115. Thus, four infrared sources attributed to newborn/forming stars have been detected. These are known as IRAS 20328+4639, IRAS 20334+4636, IRAS 20335+4637, and IRAS 20334+4654. Additionally, a radio source known as W71 is known to be associated in the region. 

Responsible for the illumination of Sh2-115 are two stars. These are known as LS III+4612 (type-O6III), and DM46 2978 (type-B0III).

Image: Composite optical image of Sh2-115 taken with the ASA 12-inch Astrograph of the Irida Observatory in Southern Bulgaria. The image was created using broadband filters (blue-band, green-band, and red-band), together with a narrow band filter that is focused on the emission of ionized hydrogen (Hα). The small bright gas-blob on the top left side of the image was initially thought to be a planetary nebula, but now it is recognized as an emission nebula known as Sh2-116.

Image Credit: Velimir Popov & Emil Ivanov 

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