Norma

Norma is a small and inconspicuous constellation in the southern hemisphere between Scorpius and Centaurus. Its name is Latin for normal, referring to a right angle, and is variously considered to represent a rule, a carpenter's square, a set square or a level. Stars. The Milky Way passes through Norma. Norma has no α or β star. These are now officially part of Scorpius - N Sco and H Sco respectively. Norma's brightest star, γ2 Normae, is only of magnitude 4.0. Among the constellation's principal stars are the following: (1) γ1 Nor and γ2 Nor comprise an easy optical double. γ2 Nor is itself a close optical double (HJ 4841). (2) ε Nor: a relatively fixed binary star (HJ 4853). The two components are of magnitude 4.54 and 6.68; the separation is 22" in PA 335°. The fainter component is itself a spectroscopic binary (mag 6.68 and 7.12). (3) ι1 Nor: a multiple star. The AB (mag 5.6 and 5.8) pair comprise a rapid binary with a period of 26.9 years; in 2000 the separation was 0.5" in PA 285°. Component C, of magnitude 8.75, is 11" away in PA 242°; it is not a physical member of the system, being only 55 light-years away, while the AB pair lie at a distance of more than 140 ly. (4) μ Nor is suspected of being an Alpha Cygni variable, with a range of 4.87–4.98. It is of spectral type O9.7 Iab. (5) R Normae is a Mira variable. Its visual range is 6.5–13.9 and its average period is 507.5 days. (6) S Normae is a well-known Cepheid variable with a range of 6.12–6.77 and a period of 9.75411 days. It is located at the centre of the open cluster NGC 6087. Deep-sky objects. Due to its location on the Milky Way, this constellation contains many deep-sky objects, the most notable of which is NGC 6087. NGC 6087 is the brightest of the open clusters in Norma; it lies in the southeastern corner of the constellation between α Centauri and ζ Arae. It is about 3500 light-years away and contains about 40 stars of the seventh to the eleventh magnitude. Its brightest member is the Cepheid variable S Normae. It is of magnitude +5.4. [Norma (constellation). Wikipedia]