The Latin word cumŭlus came into Spanish as cumulus . The concept can be used to name the accumulation or disorderly piling up of various elements .
For example: “When the meeting ended, I experienced an accumulation of sensations” , “My life is an accumulation of problems, I need a vacation” , “The accumulation of government errors caused this social crisis” .
In this framework, if someone refers to the “accumulation of difficulties” that they had to go through to reach a goal, they will be referring to all the inconveniences that they had to overcome to achieve their objective .
In the field of astronomy , on the other hand, a group of small stars that is dense to the eye is called a cluster. Star clusters are generated by the attraction produced by the mutual gravity of stars.
According to the traditional classification, it is possible to distinguish open star clusters from globular ones. Open clusters are made up of young stars (which can be between one hundred and one billion years old ), while globular clusters are made up of old stars, which can be over one billion years old.
Open clusters, on the other hand, have a smaller number of stars than globular clusters. They also break up over time due to their interaction with molecular clouds as they move through the galaxy, while globular clouds have greater degrees of stability and density, which makes them less prone to disintegration, although this does not prevent them from breaking up. sooner or later they will be destroyed.
Beyond the differences in the number of stars (which inevitably affects the mass of both types of clusters) and the age of each one, it is also possible to distinguish them by the richness in metals they present (the open ones surpass the globular ones in this aspect) and by its orbit (the globular ones belong to the halo population, and the open ones, to that of the disk).
Despite everything said, the dimensions of their nuclei are not very different: in both open and globular clusters, this can be measured in a few parsecs (the unit called parsec or parsec is used in the field of astronomy and its definition is the distance at which one astronomical unit joins with an arc angle one 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 clouds, although of an age that does not allow them to be placed in this group. Outside our galaxy, star clusters with similar characteristics have also been discovered, with masses much higher than globular ones, and they are called superclusters .
There are also superclusters in the Milky Way, and some of them are behind huge dust clouds . It is important to distinguish star clusters from stellar associations , groupings that are not united by gravity and that exhibit slow dispersion.
In the field of meteorology , cumulus clouds are groupings of clouds characteristic of the summer season, which resemble snowy mountains. Also called cumulus clouds, these clouds have a prominent vertical development and their edges are bright and well defined.
For geology , cumulus is the gathering of crystals in magma . The notion is also used to name the rock that results from this accumulation process.
Cytology , finally, appeals to the idea of cluster of differentiation to refer to the antigens found on the surface of leukocytes, used to identify the type of cell and its activity.