W50 SNR in Aquila
This deep widefield image with narrowband exposures shows a region of the Milky Way towards the constellation of Aquila centred around the supernova remnant W50. Although it doesn’t exhibit many filaments in the optical wavelength, it presents an exquisite and complete whole shell at radio wavelengths.
It was first discovered in 1958 by Gart Westerhout and classified as a supernova remnant in 1969. The first detection of associated optical filaments was in 1980 and spectroscopy conclusively proved they were part of W50. One explanation for its minimal optical emission is dust obscuration towards this area near the Aquila Rift. The distance has been estimated at 18,000 light years and might have an age of 20,000 years. The full radio shell spans 2x1 degrees in the sky and a physical size of 700 light years.
One incredible aspect of W50 is that at its heart lies the well studied microquasar binary system SS 433. This is a binary system consisting of a blue supergiant star and a black hole orbiting each other and are in the process of blasting out jets that have energised the supernova shell of W50. Another rarely seen phenomena is the interaction of W50 with both the surrounding interstellar medium and magnetic fields.
Other deep sky objects of interest in this field include the emission nebula Sh2-74, the pair of open clusters NGC 6755–6 and the bright planetary nebula NGC 6781 near the top left corner. The round blue bubble towards the south of the image is the planetary nebula candidate StDr 101, which was rediscovered by the amateur astronomers Xavier Strottner and Marcel Drechsler in August 2019. Was originally discovered as part of the IPHAS survey and is also catalogued as IPHASX J191003.4+032224 but was rejected as a planetary nebula candidate. You can find these objects in the annotated image.
[description from Sakib Rasool]