Answer: open
The image represents an open star cluster.
Open star clusters are groups of stars formed from the same molecular cloud, generally asymmetric (without structure).
An important characteristic of this type of cluster is that all its stars have the same age and similar chemical composition. In addition, they are linked to each other gravitationally, but to a lesser extent than those of globular clusters.
The stars hosted by these clusters tend to be young, massive and very hot.
Among this group are the Pleiades (represented in the image), located in the constellation of Taurus.
