Mintaka (δ Orionis) Worksheets

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Key Facts & Information

• Mintaka is a multiple star system located in the constellation of Orion. It is also one of the three main stars located in the constellation. It is the 7th brightest star in Orion and the 73rd brightest in the night sky.
• Mintaka is also known as Delta Orionis and 34 Orionis. It can be found at around 1,200 light-years/380 parsecs away from the Sun.
• This star is the westernmost star of the well-known Orion’s Belt asterism. The Orion’s Belt asterism has been known for thousands of years. It was associated with different myths and also religious beliefs.
• The word Mintaka has an Arabic origin  which translates as “belt”.
• Orion’s Belt has been known by many names in different cultures  throughout the ages. The other main stars located in the Orion’s Belt are Alnilam and Alnitak.
• The combined visual magnitude of the star system is 2.23. It is the faintest object which forms the familiar hourglass shape. The absolute magnitude is -5.8.
• The ages of the stars in Mintaka are currently unknown. They are part of the Orion OB1 Association. This is a part of the Orion Molecular Cloud Complex which is a star-forming region with stellar ages ranging up to 12 million years old.

Formation

• Orion Constellation is home to many blue stars, clusters, nebulae, and clouds of dust and gas. There is also a pretty active star formation in this constellation. All three stars in this region have many other companion stars around them except for Alnilam.
• Mintaka is the most complex stellar system in the constellation of Orion. Its age is still unknown, but it is clearly younger than the Sun and all the other stars in the constellation.
• It is a part of the Orion Molecular Cloud Complex. In this complex, stars cannot exceed 12 million years old. There was a time when gas and dust from the molecular cloud were pulled together by gravity, which resulted in many stars that we can see in the constellation.

Distance, Size & Mass

• The primary star, Mintaka Aa1, is the biggest     in the star system, which is more than 20 times bigger than the Sun, but the smallest and least massive star in the constellation. It has a mass of around 24 solar masses and a radius of about 16.5 times that of the Sun.
• The secondary star, Mintaka Ab, has around 22.5 solar masses and a radius of around 10.4 that of the Sun.
• The third star is Mintaka Aa2, which has 8.4 solar masses and a radius of 6.5 solar radii.
• The fourth star is HD 36485. It has a radius of around 5.7 solar radii. It has a mass of around 9 times more than that of the Sun.
• The fifth star is called Mintaka B. It is even smaller than the Sun with only 77% of solar radii and its mass remains unknown.

Other Characteristics

• Mintaka Aa1 is the brightest star. It is around 190,000 times brighter than the Sun. It is also the hottest star in Orion’s Belt. It is also around 5.1 times hotter than the Sun. It has temperatures of around 29,500 K. It is a blue giant of spectral class O9.5II with an absolute magnitude of -5.4 and a rotational velocity of 130 km/80.7 mi per second.
• Mintaka Ab is the second-brightest star. It is around 63,000 times brighter than the Sun. It has a temperatures of around 28,400 K, which makes it the second-hottest star in this constellation. It is 4.9 times hotter than the Sun. It is a subgiant star of spectral class B0IV. It has a magnitude of -4.2 with a rotational velocity of around 220 km/136.7 mi per second.
• Mintaka Aa2 is the third-brightest star in this constellation. It is 16,000 times brighter than the Sun. It is also the third-hottest star. It has a temperature of 25,600 K. It is 4.4 times hotter than the Sun. Mintaka Aa2 is a giant star of spectral type B1V with a magnitude of -2.9 and a rotational velocity of 150 km/93 mi per second.
• HD 36485 is the fourth-brightest star in the system being 3,300 times brighter than the Sun. It is the fourth-hottest having a temperature of 18,400 K. It is also 3.1 times hotter than the Sun. It is a main-sequence star with a spectral classification of class B.
• Mintaka B is the faintest one in the system. It has 0.431 solar luminosities. Its temperature is almost similar to the Sun at around 5.34 K. It is a 14th magnitude star.

Stellar System

• Mintaka Aa1 and Aa2 orbit each other every 5.73 days. Since they are an eclipsing binary system, its brightness varies and it is the closest one to the Earth.
• Mintaka Ab is separated by 0.26” from the main pair and orbits the primary star with a period of more than 400 years.
• The first eclipse causes the magnitudes to drop from 2.23 to 2.35, while the second eclipse makes it drop to 2.29.
• HD 36485 is a spectroscopic binary system with a dim class A companion. The stars orbit each other every 30 days. It is still unknown if Mintaka B is truly related to the Mintaka star system.

Location

• Mintaka is located in the Orion Constellation, which is known as the celestial hunter. It is the part of the three stars forming the hunter’s belt. It is also the westernmost star. Orion’s Belt is often used to search for the constellation itself.
• The Orion Constellation is also home to two first magnitude stars, which are Rigel and Betelgeuse. It also hosts the nearest star formation to Earth.
• This constellation is prominent in the sky every winter for observers in the Northern Hemisphere, and for observers in the Southern Hemisphere, during summer, where it appears upside down.

The Future

• Mintaka is massive enough that one day it will explode as a supernova, which will not happen for a million years. Its unique eclipsing binary system will still be studied for decades because these systems and how they work are still a mystery to us.

Did You Know?

• Mintaka is the right-most of the stars of Orion’s Belt when viewed from the Northern Hemisphere facing south when Orion is near the meridian.
• Orion’s Belt was known as Weighing Beam for the Chinese. The stars in the belt and a couple more from the constellation are included in this asterism. Alnilam is known as the Third Star of Three Stars.
• Mintaka can be used as a guidepost for finding east and west because it is one of the closest stars to the celestial equator.
• Orion and Sirius were associated with the divine beings Isis and Osiris who were believed to have come from Orion’s Belt and Sirius to create mankind.   
• The three pyramids of the Giza Plateau simulate the alignment of the three belt stars. The air shafts of the pyramids are pointed directly towards the constellation.
• Two large pyramids and a temple in Mexico were discovered to point directly to Orion. These were built in the 2nd century BC, and one of them is exactly half as tall as the Great Pyramid of Giza.
• In Puerto Rico and Philippines, the three stars represented the three biblical Magi and they named it Tres Reyes Magos.
• In pre-Christian Scandinavia, the belt is known as Frigg’s Distaff or Freya’s staff, while in northwestern Mexico, the Seri people called it Hapj which denotes a hunter.