What are the main types of star clusters? check all that apply.

The star clusters are defined as the enormous groups of stars. The three major types of clusters are as follows-

(1) Globular clusters- They are almost symmetrical and forms a circular type of system. They are many hundreds and thousands of stars. The surface temperatures of these stars are approximately 4000 K. These stars represent the oldest portion of the Milky Way Galaxy. Here, the stars are closely oriented due to the high gravitational force.

(2) Open clusters- These include stars of different ages and are mostly present in the disk of the Galaxy. These stars are comparatively younger than the globular clusters and have a diameter of less than about 30 light-years. Here, the stars are not closely oriented, whereas they are scattered as a result of which they are named as the open clusters.

(3) Stellar associations- These stars are about 100–500 light-years in terms of diameter. The stellar association is a bunch of very young stars that contains about 5 to 50 hot and bright Orange as well as Blue stars are scattered over a specific boundary in space.

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.

the element that provides strength to the exoskeletons of clams and oysters is phosphorus. this is so because calcium carbonate is the main component in the shells.

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