In the vast expanse of space, a peculiar red nebula known as the “Hand of God” was recently observed in the Cosmos. This cometary cloud, identified as CG 4 and located in the Stern constellation, spans eight light years in length and about half a light year in width.
Despite its name, cometary clouds like CG 4 are not associated with comets. These clouds are a unique type of nebula where gas and dust form long tails that are shaped and eroded by the surrounding hot ionized material. The distinctive appearance of CG 4, resembling giant worms from the novel “Dune,” has led to its nickname as the “Hand of God” among astronomers.
Cometary clouds, classified as cometary globules, have been known since 1976 and continue to be challenging objects for observation due to their dark nature. However, the use of a Hydrogen-Alpha filter on the Dark Energy Camera has enabled the detection of a red glow surrounding CG 4, thanks to its ability to capture the faint light emitted by ionized hydrogen.
The light from hot massive stars not only ionizes hydrogen in these clouds but also plays a role in their formation. The “head” or “hand” of the CG 4 cloud, containing enough material for the birth of multiple sun-sized stars, is being disrupted by the process of star formation. Yet, the heating and destruction of the cloud present obstacles to the stable and cool conditions required for new star birth.
Situated within the Gamma Velorum (GAM) cluster, CG 4 is part of a group of 32 similar cometary clouds, all showing tails oriented away from the Vela pulsar due to its intense radiation. This mesmerizing celestial sight is further enhanced by the presence of the distant ESO 257-19 galaxy, appearing to interact with the giant worm-like structure of CG 4, despite being over 100 million light years apart.