An image captured by the OmegaCAM instrument mounted on ESO’s VST in Chile shows details of the nebula cataloged as Sh2-284. It’s part of the VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+), a survey that included over 500 million objects in the Milky Way to improve our understanding of stars’ life cycles. Sh2-284 is a sort of star nursery whose shape was compared to that of a cat’s face and for this nicknamed “smiling cat”.
Sh2-284 belongs to the class of emission nebulae, interstellar clouds of gas that is ionized, usually by stars in the area, and consequently emit colored light. It also belongs to the subclass of H II regions because it is associated with massive young stars.
At the center of the Sh2-284 nebula is the Dolidze 25 open cluster. With its stars emitting powerful radiation and stellar winds, it’s the main reason for the ionization that generates the red and orange hues of Sh2-284.
Stellar winds from the Dolidze 25 cluster at the center of the Sh2-284 nebula hollow its core by pushing the gas outward. One of the consequences is the creation of the pillar-like formations where the winds meet areas where the materials are denser. In the image, those pillars are small but actually, they are several light-years wide and contain large amounts of gas and dust that are compressed creating the conditions in which new stars can form. One of the pillars to the right of the central area looks like a finger that is pointing right at the core.
Various optical filters were used on the 256 million pixels OmegaCAM to capture this image of the Sh2-284 nebula during the VPHAS+ survey. This camera was designed by an international consortium to have sufficient sensitivity to obtain the very details of the formation processes of stars and their circumstellar disks and molecular clouds such as the H II regions in which they form. The OmegaCAM is mounted on the VLT Survey Telescope (VST) owned by the Italian National Institute for Astrophysics, part of the Italian collaboration with ESO.
The Sh2-284 nebula is about 15,000 light-years away from Earth, but estimates of its distance differ significantly. Instead, astronomers all agree regarding the interest in the star formation processes taking place inside it, which led to obtaining this breathtaking image and lots of useful information for researchers.
