Exploring Open Star Clusters: M35 and NGC 2158

Explore the captivating realm of clusters. Unique collections of relatively young stars that originate from the same molecular cloud and are held together by their mutual gravitational attraction. These open clusters consist of stars that share characteristics, such as age and metal content.

Contrary to belief open clusters exhibit a wide range of diversity. They can be found in both distant locations appearing either diffuse or compact and encompassing both youthful and mature stages. A perfect example showcasing this diversity is observed in the clusters known as M35 and NGC 2158. Although they appear close to each other these clusters display striking contrasts that make for an intriguing study.

M35, situated towards the bottom left is relatively near to Earth at a distance of 2,800 light years. This cluster is still considered young at around 150 million years old. Has a scattered arrangement with roughly 2,500 stars spread across a diameter of about 30 light years. The vibrant blue hue emanating from this cluster emphasizes the presence of stars within its stellar population.

In contrast NGC 2158 can be found towards the top right position. This cluster is four times distant from Earth than M35, significantly older by ten times and exhibits a much more condensed structure. Its radiance appears yellow due, to the absence of massive stars that have already undergone nuclear fusion depletion and subsequent supernova events. NGC 2158 only has stars in mass, to our Sun emitting a pleasant yellow light.

Open clusters don't last forever. Over time the stars gradually move apart in space weakening the forces that hold them together until eventually the cluster completely dissolves. The secrets of clusters continue to captivate us as we explore these celestial wonders.

Image credit; CFHT, Coelum, MegaCam, J. C. Cuillandre (CFHT) G. A. Anselmi (Coelum).