# Star Clusters - A Rundown When a gas cloud collapses, it typically doesn't collapse on its own accord. Instead, it's typically part of a larger system of fragmented molecular clouds - each one originating from a single, large progenitor cloud. These clouds remain gravitationally bound to each other even as they coalesce into stars, turning into clusters! For those who collapse and writhe on the floor without a rigorous definition, here: >[!Success] Definition >A stellar cluster is a closely-associated, gravitationally bound assortment of stars with similar proper motions and properties (e.g metallicity) with each other. # Globular Clusters Let's start with the "macro" before the "micro". Globular clusters are ![[Pasted image 20230707133827.png]] The image above is a diagram of a globular cluster. It is to note that the F606-F814 (the value which dictates how blue or red the stars in the graph are) is very, very high compared to the open cluster - remember that the higher the numerical value for magnitude, the dimmer a star is in the wavelength chosen! Below is a guide for the types of stars present in the diagram: --> BS --> blue straggler HB --> horizontal branch MSTO --> main sequence turnoff RGB --> red giant branch --> massive, old, low metallicity (formed during early milky way, galaxy collision?) # Open Clusters Originating from smaller clouds, these clusters are younger than globular, as evidenced by the colour-magnitude diagram below. These clusters come from diffuse, supernova remnant gas clouds, hence they have much less material than a globular cluster, which is created by galaxial collisions and the intermixing of intergalactic dust. secondary type of cluster - open cluster: ![[Pasted image 20230707134210.png]]