RCW33

RCW33, it's 60 minutes of exposure in SHO with Takahashi FSQ-106ED 106/382 f3/6 telescope, QHY 600M Pro camera, it's 12 shots of which in Ha 4x300 seconds, in OIII 4x300 seconds and in SII 4x300 seconds, processing with Pixinsight and Photoshop. All data and shots were captured with Telescope Live. RCW33 or GUM 17 is a large emission nebula visible in the constellation Velas. It is located in the northwestern part of the constellation, about a quarter of the angular distance between the stars Suhail (λ Velorum) and Naos (ζ Puppis). It appears as an extensive and faint irregular spot, easily detectable and photographed with the aid of filters through a medium-power telescope. Its strongly southern declination means that from the boreal regions its observation is particularly difficult from the lower temperate belt, while north of 48°N it is always invisible. From the southern hemisphere, on the other hand, it can be observed for almost every night of the year. The best time for its observation in the evening sky is from December to May.

Its galactic position is the subject of controversy: according to some studies, in fact, it would be associated with the blue giant HD 75759, located about 1000 parsecs (about 3300 light years) away; if this were true, this nebula would be physically bound to the Vela Molecular Ridge, a large molecular nebula complex, and in particular to the molecular cloud called VMR D. There would also be other stars responsible for the ionization of its gases, such as HD 75724. The star-forming region with which it is associated is referred to as Avedisova 2169 in the catalog of the same name published in 2002. According to other studies, however, this cloud would be associated with the young open cluster Tr 10, located on the southwestern edge of the nebula, whose distance, however, is around 420 parsecs (1370 light years); if so, Gum 17 would not be part of the Vela Molecular Ridge complex, but would be about 500 parsecs from it in the direction of the Sun, at a distance comparable to that of the Gum Nebula and the Vela OB2 association (Cr 173).

Within the nebula, several IRAS sources are known, whose spectral characteristics are comparable to those of young Class I stellar objects, probably T Tauri stars; This association of young stars has been named with the acronym Vela T2. The presence of these stars is evidence that star formation phenomena have been active in the cloud in the astronomically recent past.