Scientists call these nebulae cometary globules, because
of gaseous cloud shapes resemble comets (only much, much greater), and
similarly to comets, such nebulae are shaped by stellar wind. While
shape of comets is created by regular stellar wind from our Sun, CG 4
was probably formed by supernova explosion, as it points to the
location of supernova remnant in the constellation Vela.
The deep and detailed image of this very faint object was acquired
by the CielAustral group of astrophotographers (Laurent
Bourgon, Jean-Claude Canonne, Nicolas Outters, Philippe Bernhard and
Didier Chaplain) from their observatory located at Obstech - Observatorio El
Sauce in Chile. Image was acquired using G4-16000 camera on
50 cm CDK20 telescope. Total exposure time was almost 60 hours.