A stellar cluster is a group of stars that are gravitationally bound to each other, share a common origin, and are located in a relatively small region of space.

Stellar clusters are formed when a giant molecular cloud, a dense region of gas and dust, collapses under its own gravity. This collapse triggers the formation of individual stars within the cluster.

Open clusters are younger and contain fewer stars (typically a few hundred to a few thousand), while globular clusters are older and contain more stars (typically hundreds of thousands to millions). Open clusters are located in the spiral arms of galaxies, while globular clusters are located in the halo. Open clusters are more massive than globular clusters.

Studying stellar clusters provides insights into the formation and evolution of stars, helps us understand the structure and dynamics of galaxies, and can be used to estimate the age of the universe.

The Pleiades is a well-known open cluster located in the constellation Taurus. It is visible to the naked eye and contains hundreds of stars.

Omega Centauri is a prominent globular cluster located in the constellation Centaurus. It is one of the largest and brightest globular clusters in the Milky Way.

The mass range of stars typically found in open clusters is 0.1 to 10 solar masses. This is because open clusters are formed from the collapse of a giant molecular cloud, which contains a mixture of gas and dust with a range of densities.

The mass range of stars typically found in globular clusters is also 0.1 to 10 solar masses. This is because globular clusters are also formed from the collapse of a giant molecular cloud, but the conditions in the cloud are different from those in open clusters.

The typical age of an open cluster is 10 million to 1 billion years. This is because open clusters are relatively young and have not had enough time to disperse or be disrupted by external forces.

The typical age of a globular cluster is more than 100 billion years. This is because globular clusters are much older than open clusters and have had more time to evolve.

Stellar clusters provide a natural laboratory to study stars of different ages and masses, help us understand the initial conditions for star formation, and can be used to test theories of stellar evolution.

Stellar clusters help us understand the distribution of stars in galaxies, can be used to trace the spiral arms of galaxies, and can be used to estimate the mass of galaxies.

Stellar clusters can be used to estimate the age of the oldest stars in the universe, the age of the Milky Way, and the age of the universe.

Stellar clusters do not contain stars of different ages. All the stars in a stellar cluster are formed at the same time from the same giant molecular cloud.

Planetary nebulae are not stellar clusters. They are the remnants of stars that have shed their outer layers and are now in the final stages of their evolution.