Alnilam, The Star From the Orion Belt

Orion belt or more commonly known as Luku or Waluku in Indonesia. is a Rasi consisting of three stars in line in the middle. They rise just east and set right in the west. It was midnight overhead. The three stars, from west to east, are named Mintaka, Alnilam, and Alnitak. According to astronomer Jim Kaler, as quoted by Space.com, the two outermost stars, namely Alnitak and Mintaka, are derived from an Arabic phrase meaning belt. The Alnilam means a string of pearls. maybe his name was given because Alnilam appeared with a striking blue star.

In Greek mythology, the three stars symbolize Orion's belt, the hunter. In view of the northern hemisphere, the hunter is in a standing position carrying a left shield and a mace in his right hand.

British Polish observatory astronomer in Greenwich Tom Kerss calls the three stars associated with the biblical story of three wise men (magi) from the east visiting the baby Jesus.

On this occasion, let's get to know Alnilam, one of the stars on the Orion Belt. Alnilam (otherwise known as the Orionist Epsilon) is a super-giant blue star-type B0 Ia. This star is a very hot star, its surface temperature is estimated at 19,000 degrees Celsius. Far different from the surface temperature of the Sun which is only 5,500 degrees Celsius.

With an apparent magnitude of +1.69, Alnilam is the 4th brightest star in the constellation Orion, as well as the 29th brightest star in the night sky. Alnilam is also one of 58 stars used in navigating sailors to know its position.

Like most other blue giant super stars, Alnilam is now experiencing mass loss at a very high level. Studies show that once Alnilam threw his star wind, its energy is equivalent to two million times the mass of the Sun.

It will eventually make the star of Alnilam evolve into a super giant red star even more glowing than Betelgeuse who became his neighbor in the constellation Orion.

Using Hipparcos satellite data released in 1997, Alnilam's star distance reaches 1,342 light-years from Earth or about 411.52 parsecs. In other words, with the spacecraft traveling at the speed of light, it still takes 1,342 years to get to Alnilam.

However, in 2007, the Hipparcos data was revised, and it was learned that Alnilam apparently was at a greater distance, 1,976 light-years or 606,06 parsecs. Meanwhile, the galaxy-centric distance (a distance of stars to the galactic center) to Alnilam is 7,758 parsecs or 25,303 light-years.

Radius Alnilam is known 15.6 times larger than the Sun. If the radius of the Sun is 695,800 kilometers, then Alnilam is estimated at 10,880,611.09 kilometers.

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