Sh2-9, also called Gum 65 is combination emission and reflection nebula in the Scorpius constellation, surrounding the multiple star system Sigma Scorpii.
The nebula is northeast of the globular cluster, Messier 4.
Although it was a tricky challenge to image this under my suburban Bortle 6/7 skies, I’m quite pleased with the outcome. The complimentary colours of cool Al-Niyat and warm M4 seem to balance one another nicely. The big Tak has it’s spacing perfect now, so I finally have round stars in all four corners, and the star definition in M4 itself is remarkable.
I’ve ordered a new TOA-35 reducer to give me a wider FOV, so when that arrives, I’ll be able to frame some of these larger objects with even more “space” to allow context.
Andy Campbell, Melbourne Australia, May 2021
About this Nebula
Sh2-9, also called Gum 65 is combination emission and reflection nebula in the Scorpius constellation, surrounding the multiple star system Sigma Scorpii. The nebula is a few arcminutes to the northeast to Messier 4, and can be easily seen by small telescopes.
Sharpless 9 is a red emission nebula that surrounds the star Sigma Scorpii. It is thought the star Sigma Scorpii, a variable giant star, is ionizing this region. It is also recorded as reflection nebula C130. This region is noted as both an emission and reflection nebula, although sometimes only one aspect is noted. The magnitude 1.1 Antares is also relatively nearby to this nebula.
The paper A 2.3 GHz radio continuum map of the upper Scorpio region found that one of strongest 2.3 GHz sources in their region of study, which they called Source 4, coincided with Gum 65/Sharpless 9/C140
There is a radio source on the edge, and it has been proposed this because there is a collision between this nebula and the Dark nebula Kh 527.
It was discovered by Philippe Loys de Chéseaux in 1745, M4 was the first globular cluster in which individual stars were resolved.