Alnilam

It is used in astronomical navigation, which is a technique which consists of determining your own position with the help of certain stars and the measuremznt of their altitude. 
Epsilon Orionis is expected to become a red supergiant and explode as a supernova. It is surrounded by a molecular cloud "NCG 1990" which it illuminates to form a beautiful reflexion nebula. Molecular clouds are interstellar nebulae (diffuse celestial objects composed of rarefied gas and:or dust) of sufficient density and size to allow the formation of H2, the molecular hydrogen. And reflexion nebulae are dust clouds that simply reflect the light of one or more neighbouring stars. 
It's stellar winds can reach 2000 km/s, causing mass losses 20 milion times greater than those of our sun. 
It has a temperature of 25 000 K (24 727 °C) and is 375 000 times brighter than the Sun. 
It's apparent magnitude is only 1.70. Apparent magnitude is a measure of the irradiance of a celestial object observed from Earth.                                       

Alnilam's significance extends beyond its celestial beauty and navigational utility. It serves as a crucial object of study for astronomers seeking to unravel the mysteries of stellar evolution. As a blue-white supergiant, it represents a stage in the life cycle of massive stars, offering insights into the processes governing their formation, development, and ultimate fate. By observing Alnilam's behavior, scientists can refine their understanding of stellar dynamics, including the mechanisms driving stellar winds, the synthesis of heavy elements, and the dramatic transitions leading to supernova explosions. Thus, Alnilam stands not only as a beacon in the night sky but also as a celestial laboratory, enriching our comprehension of the cosmos and our place within it.

Indeed, blue-white supergiants like Alnilam are in a critical phase of their evolution, where they have exhausted the hydrogen fuel in their cores and are undergoing nuclear fusion of heavier elements. Observing Alnilam helps astronomers track the transition from main-sequence stars to supergiants, providing valuable data for stellar evolution models. 

Then the existence of supergiants like Alnilam sheds light on the formation mechanisms of massive stars. By studying Alnilam's properties and its environment, astronomers can refine theories about how massive stars form from molecular clouds and what factors influ​​​​​​​ence their initial mass and composition. And as a candidate for future supernova explosion, Alnilam offers a unique opportunity to study the properties an​​​​​​​d behavior of supernova progenitors. By monitoring Alnilam's characteristics over time, astronomers can identify signs of impending supernova events ​​​​​​​and refine models predicting the outcomes of such explosions. Credit : Shutterstock                                                      

 At last, b​​​​​​​lue-w​​​​​​​hite supergiants like Alnilam are sites of intense nuclear fusion, where elements heavier than hydrogen and helium are synthesized. By stu​​​​​​​dying th​​​​​​​e elemental abundances in Alnilam's spectrum and comparing them to theoretical predictions, astronomers can gain insights into the nuclear fusion processes occurring within massive stars.

Credit : NASA