The Lupus Constellation

Lupus is a constellation located in the deep Southern Sky. Its name is Latin for wolf. Lupus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations, although it was previously an asterism associated with the neighbouring constellation Centaurus. Lupus is bordered by six different constellations, although one of them (Hydra) merely touches at the corner. The other five are Scorpius (the scorpion), Norma (the right angle), Circinus (the compass), Libra (the balance scale), and Centaurus (the centaur). Covering 333.7 square degrees and 0.809% of the night sky, it ranks 46th of the 88 modern constellations. The official constellation boundaries are defined by a twelve-sided polygon. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 14h 17m 48.0635s and 16h 08m 36.6735s, while the declination coordinates are between −29.83° and −55.58°. The whole constellation is visible to observers south of latitude 34°N.

Overall, there are 127 stars within the constellation’s borders brighter than or equal to apparent magnitude 6.5. In his book Star Names and Their Meanings, R.H. Allen gave the names Yang Mun for Alpha Lupi, the brightest star in Lupus, and KeKwan for the blue giant Beta Lupi, both from Chinese. However, the first name is in error; both stars were part of a large Chinese constellation known in modern transliteration as Qíguān, the Imperial Guards. Most of the brightest stars in Lupus are massive members of the nearest OB association, Scorpius-Centaurus. Alpha Lupi is an ageing blue giant star of spectral type B1.5 III that is 460 ± 10 light-years distant from Earth. It is a Beta Cephei variable, pulsating in brightness by 0.03 of a magnitude every 7 hours and 6 minutes.

Towards the north of the constellation are globular clusters NGC 5824 and NGC 5986 and close by the dark nebula B 228. To the south are two open clusters, NGC 5822 and NGC 5749, as well as globular cluster NGC 5927 on the eastern border with Norma. On the western border are two spiral galaxies and the Wolf-Rayet planetary nebula IC 4406, containing some of the hottest stars in existence. IC 4406, also called the Retina Nebula, is a cylindrical nebula at a distance of 5,000 light-years. It has dust lanes throughout its centre. Another planetary nebula, NGC 5882, is towards the centre of the constellation. The transiting exoplanet Lupus-TR-3b lies in this constellation. The historic supernova SN 1006 is described by various sources as appearing on April 30 to May 1, 1006, in the constellation of Lupus. ESO 274-1 is a spiral galaxy seen from edge-on using Lambda Lupi and Mu Lupi as markers. NGC 5986 is a globular cluster in the constellation. It is 33,900 light years distant from Earth. The cluster is notable because it contains two very bright A-F class stars which are likely in their last stage of evolution of the asymptotic giant branch. The cluster has an apparent magnitude of 7.52. It can be found 2.5 degrees to the west-northwest of the star Eta Lupi. Credit: Wikipedia.