The Scorpius Constellation

Scorpius is one of the constellations of the zodiac. Its name is Latin for scorpion. Scorpius is one of the 48 constellations identified by the Greek astronomer Ptolemy in the second century. It is an ancient constellation that pre-dated the Greeks. It lies between Libra to the west and Sagittarius to the east. It is a large constellation located in the southern hemisphere near the centre of the Milky Way. Scorpius is the 33rd constellation in size, occupying an area of 497 square degrees. It lies in the third quadrant of the southern hemisphere and can be seen at latitudes between +40° and -90°. The neighbouring constellations are Ara, Corona Australis, Libra,  Lupus, Norma, Ophiuchus and Sagittarius. Scorpius belongs to the Zodiac family of constellations, along with Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Sagittarius, Capricornus, Aquarius and Pisces.

Scorpius contains many bright stars, including Antares (α Sco), ” rival of Mars, ” so named because of its distinct reddish hue. Antares is a red supergiant star with a visual magnitude of 0.96, approximately 550 light-years distant   from the Sun. It is the brightest star in the Scorpius constellation and the 16th brightest star in the night sky. The star belongs to the spectral class M1.5lab-b and has the radius about 883 times solar. It is approximately 10,000 times more luminous than the Sun, and has between 15 and 18 solar masses. The star’s estimated age is about 12 million years. Antares is classified as a type LC slow irregular variable star. The star’s magnitude slowly varies from 0.88 to 1.16. It has a companion star, Antares B, about 529 astronomical units away. Antares B has the stellar classification B2.5 and an apparent magnitude of 5.5. It is 170 more luminous than the Sun and has an orbital period estimated at 878 years. Shaula is the second brightest star in Scorpius and the 25th brightest star in the sky. It is approximately 700 light-years distant   from the solar system. Lambda Scorpii is a multiple star system with three visible components, Lambda Scorpii A, Lambda Scorpii B, and Lambda Scorpii C. Lambda Scorpii A is a triple star system composed of two-class  B stars and a pre-main sequence star.   Lambda Scorpii B lies 42 arc seconds away from the first component, and Lambda Scorpii C is a 12th-magnitude  star 95 arc seconds away from component A. The primary star in the Lambda Scorpii A system is a Beta Cephei type variable. The estimated age of the star system is about 10-13 million years. Lambda Scorpii’s traditional name, Shaula, comes from the Arabic al-šawlā´, which means “the raised (tail).” Theta Scorpii is an evolved bright yellow giant star belonging to the spectral class F0 II. It has an apparent magnitude of 1.87 and is approximately 300 light-years distant   from the solar system. The star has 5.7 solar masses, 26 times the solar radius, and is 1,834 times more luminous than the Sun. It has a companion with an apparent magnitude of 5.36 located 6.470 arc seconds away from the primary star. The star’s traditional name, Sargas, is of Sumerian origin. The meaning of the name is unknown.

Due to its location straddling the Milky Way, this constellation contains many deep-sky objects. Messier 4 is a globular cluster in Scorpius, with an apparent magnitude of 5.9 and are approximately 7,200 light-years distant from the solar system. It was the first globular cluster discovered in which individual stars could be resolved. The brightest stars in M4 have an apparent magnitude of 10.8. The estimated age of the cluster is around 12.2 billion years. M4 is about 75 light-years across.   It was discovered by the Swiss astronomer Philippe Loys de Chéseaux in 1746 and included in Messier’s catalogue in 1764. Along with NGC 6397 in the constellation Ara, which is also 7,200 light-years away,   Messier 4 is the closest globular cluster to our solar system. Messier 6 is an open cluster also known as the Butterfly Cluster because its stars form a shape similar to that of a butterfly. The cluster was first discovered by the Italian astronomer Giovanni Batista Hodierna in 1654, and Charles Messier included it in his catalogue in 1764. The bright stars in M4 are mostly hot, blue, class B stars, but the brightest one is a class K orange giant, BM Scorpii. The Butterfly Cluster has an apparent magnitude of 4.2 and are approximately 1,600 light-years distant from the Sun. Messier 7 is another open star cluster in Scorpius, located near the scorpion’s stinger. It has an apparent magnitude of 3.3. It is also known as the Ptolemy Cluster because it was the Greek astronomer Ptolemy, who first recorded it in 130 AD. The Ptolemy Cluster contains about 80 stars, the brightest of which has a visual magnitude of 5.6. M7 is approximately 980 light-years distant from the solar system. It is roughly 25 light-years in diameter. The age of the cluster is estimated to be around 200 million years. Messier 80 is a globular cluster discovered by Charles Messier in 1781. It has an apparent magnitude of 7.87 and are approximately 32,600 light-years distant from the Sun. M80 is about 95 light-years in diameter and contains hundreds of thousands of stars. It is one of the most densely populated clusters in our galaxy. It is home to a significant number of blue main-sequence stars that appear to be much younger and more luminous than stars at the main-sequence turn-off point for the cluster. The Cat’s Paw Nebula is an emission nebula in Scorpius. It is a vast star-forming region and one of the most active stellar nurseries containing some of the most massive stars known in the Milky Way. It is believed to contain tens of thousands of stars. The nebula was discovered by the English astronomer John Herschel in 1837. The Butterfly Nebula is a bipolar planetary nebula in Scorpius. It has an apparent magnitude of 7.1. It is one of the most structurally complex nebulae known. The central star, a white dwarf, has a surface temperature in excess of 200,000 K, which makes it one of the hottest stars in the galaxy. It has about 0.64 solar masses and is enveloped in a very dense equatorial disc of dust and gas. NGC 6357 is a diffuse nebula in Scorpius. It contains many proto-stars and young stars. It got the name War and Peace Nebula because, when observed in infrared, the nebula’s western part resembles a dove, while the eastern part resembles a skull. The nebula contains Pismis 24, an open star cluster that includes several very massive stars. One of the stars, designated Pismis 24-1, has almost 300 solar masses, and it was thought to be the most massive star known until it was discovered to be a binary or multiple star system. Pismis 24-1 is one of the most luminous stars known. Credits: Constellation Guide, Wikipedia.