The Latin word cumŭlus He arrived in Spanish as cumulus . The concept can be used to name the accumulation or the messy stacking of various elements .
For example: “When the meeting ended, I experienced a cluster of sensations”, “My life is a cluster of problems, I need a vacation”, “The accumulation of errors of the government caused this social crisis”.
In this context, if someone refers to the "Cluster of difficulties" that he had to go through until reaching a goal, he will be referring to all the inconveniences that he had to overcome to fulfill his objective .
In the field of astronomy , on the other hand, is called the cluster set of small stars which is thick in sight. The star clusters are generated by the attraction produced by the mutual gravity of the stars.
According to the traditional classification, it is possible to distinguish open star clusters from globular ones. The open clusters they are formed by young stars (whose antiquity it can be between one hundred and one billion years old), while the globular clusters They consist of old stars, whose antiquity can exceed one billion years.
Open clusters, on the other hand, have a lower amount of stars than globular clusters. They also disintegrate over time because of their interaction with molecular clouds as they travel through the galaxy, while the globular ones have higher degrees of stability and density, which makes them less prone to disintegration, although this does not prevent sooner or later they are destroyed.
Beyond the differences in the number of stars (which inevitably affects the mass of both types of clusters) and the age of each, it is also possible to distinguish them by the richness in metals that present (the open ones surpass the globular ones in this aspect) and by their orbit (the globular ones belong to the population of the halo, and the open ones, to the one of the disk).
Despite all that has been said, the dimensions of its nuclei are not very different: both in open clusters and in globular clusters, it can be measured in a few parsecs (the unit called parsec or parsec it is used in the field of astronomy and its definition is the distance at which a unity astronomical joins with an arc angle a second).
In the 1980s and 1990s, some researchers discovered that this classification was not sufficient to include all types of star clusters that exist. In the Magellanic clouds , to cite an example, there are clusters of dimensions comparable to those of the globular, although of an age that does not allow them to be placed in this group. Out of our galaxy stellar clusters of similar characteristics have also been discovered, with masses far superior to those of the globular ones, and are called superclusters.
In the Milky Way there are also superclusters, and some of them are behind huge clouds of dust It is important to distinguish star clusters from stellar associations, clusters that are not linked by gravity and that have a slow dispersion.
In the field of meteorology , the clusters are cloud clusters characteristics of the summer, which resemble mountains with snow . Also calls cumulus , these clouds have an outstanding vertical development and their edges are bright and well defined.
For the geology , cluster is the meeting of crystals in magma . The notion is also used to name the rock that results from this accumulation process.
The cytology Finally, it appeals to the idea of cluster of differentiation to refer to the antigens found on the surface of leukocytes, used to identify the class of cell and its activity