Constellations: Norma 'the Set Square' Content from the guide to life, the universe and everything

Constellations: Norma 'the Set Square'

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The shield of the Science, Mathematics and Engineering faculty of the h2g2 University.Constellations: Overview | Andromeda | Antlia | Apus | Aquarius | Aquila | Ara | Aries | Auriga | Boötes | Caelum
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Goodbye Norma Jean
Though I never knew you at all
You had the grace to hold yourself
While those around you crawled.

– 'Candle In The Wind' lyrics by Bernie Taupin, famously recorded by Sir Elton John

Name:Norma
Formerly:Norma et Regula
Genitive:Normae
Short form:Nor
Meaning:the Set Square; the Carpenter's (or Surveyor's) Level
Area:165 square degrees
Co-ordinates1:Right Ascension 16h, Declination −50°
Origin:Modern

Norma is a small southern constellation completely superimposed on an arm of the Milky Way. It shares its borders with Scorpius, Lupus, Circinus, Triangulum Australe and Ara.

History

When this star grouping was created by Nicolas Louis de Lacaille (1713 - 62), he named it L'Équerre et La Règle, which meant 'The Set Square and The Ruler'. The French astronomer is famous for his posthumous catalogue Coelum Australe Stelliferum which described 14 new constellations and 42 nebulous objects among almost 10,000 southern stars. This information was garnered on a mid-18th Century expedition to the Cape of Good Hope, effectively a blank canvas sky to map for Lacaille, who used the planet Mars as a point of reference.

During a comparatively short life, Nicolas Louis de Lacaille made more observations and calculations than all the astronomers of his time put together.
– Joseph Jérôme Lefrançais de Lalande (1732 - 1807)

L'Équerre et La Règle was Latinised to Norma et Regula  (the Level and the Square), eventually becoming just Norma, which the constellation is known as today.

Stars

A lower case Greek letter combined with the genitive of the constellation name is known as a star's 'Bayer designation', after the man who devised the system of cataloguing stars. Some stars have proper names as well, for example, alpha Canis Minoris is Procyon, but there are no named stars in Norma. Other stars, like HD 148937, are known by their catalogue number. Newly discovered variable stars like QU Normae are given upper case English letters.

Normally the Greek-lettered stars are assigned in order of brightness per constellation, eg alpha Carinae, or Canopus, is the luminary of Carina. However, when the IAU reordered the constellation boundaries in 1922, they reassigned some of Norma's stars to neighbouring constellations, therefore there is no longer an alpha or a beta Normae.

HD 148937 is a blue hypergiant star surrounded by a bipolar nebula (NGC 6164-5). This star is so hot it emits ultraviolet light which heats up the gas of the nebula, causing it to glow. The nebular gas is believed to have been ejected at high speed from the star, and has already expanded to a distance of four light years2. Now at the end of its stellar lifetime, HD 148937 is expected to go supernova at some point in the future, but we don't know when. Until then, thanks to X-ray observatories, we have a ringside seat to enjoy the final spectacular performance of this supermassive star.

Mu Normae is a blue-white supergiant and part of a group of stars which together form NGC 6169, more commonly known as the Mu Normae Cluster.

S Normae is a Cepheid variable-type which has the spectral classification F8-G0Ib and is a member of the open cluster designated NGC 6087.

Star Table

StarDesignationBrightness
(magnitude)
Distance
(light years)
Spectral classification
and/or comments
γ2gamma2 Nor+4.02130Yellow giant
εepsilon Nor+4.5 and +6.6400Binary system
ιiota Nor+4.6 var140 avMultiple
ηeta Nor+4.65200Yellow giant
δdelta Nor+4.72123White dwarf
κkappa Nor+4.94440Yellow giant
γ1gamma1 Nor+4.99400White giant
QUQU Nor+5.35 var B1.5Iape
μmu Nor+5.53,500Member of NGC 6169
λlambda Nor+5.45450White subgiant
SS Nor+6.1/+6.7 var F8-G0Ib
HD 148937 +6.774,200Creates NGC 6164-5
HD 142415 +7.34 var111Yellow dwarf/
has a planet

Deep-sky

The New General Catalogue (NGC) was compiled by John Louis Emil Dreyer (the director of the Armagh Observatory from 1882 to 1916). Other notable features of Norma are listed in other catalogues, like the Menzel.

NGC 6164-5 is a bipolar emission nebula. The massive star HD 148937 has thrown off gas and then illuminates it, which we can see thanks to the image taken by the Gemini Observatory and supplied to Astronomy Picture of the Day.

NGC 5946 is a globular cluster discovered by John Herschel in July 1834.

The Norma Cluster aka ACO 3627 is a cluster of galaxies up to 250 million light years away.

Menzel 3 is the absolutely breathtaking bipolar nebula commonly called the Ant Nebula. The speed that the gas is travelling has been measured at a mind-boggling 3.5 million km/hr; this is the fastest that has been recorded for this type of nebula.

Discovered in 1936, the doughnut-shaped planetary nebula Shapley 1 is better known as Shapley's Ring and the Fine Ring Nebula, which are easier to remember than its official designation of PK 329+2.1.

James Dunlop

NGC 6067, NGC 6087, NGC 5999 (Dun 343), NGC 6031 (Dun 359), NGC 6134 (Dun 412) and NGC 5925 (Dun 357) are all open star clusters which were discovered by Scottish astronomer James Dunlop (1793 - 1848) when he was working at Parramatta Observatory, New South Wales, Australia.

Deep-sky Table

CatalogueTypeBrightness (m)Distance
(light years)
Remarks
Menzel 3Bipolar nebula+13.83,000Ant Nebula
NGC 6164-5Bipolar emission nebula+6.74,200Pre-supernova
Shapley 1Planetary nebula+134,700Fine Ring Nebula
NGC 5946Globular cluster+9.634,600h 3607
NGC 6087Open cluster+5.42,91040+ stars
NGC 6067Open cluster+5.64,620100+ stars
NGC 6169Open cluster+7.03,590Mu Normae Cluster
ACO 3627Galaxy clusterVar250mThe Norma Cluster

Meteor Showers

The meteor shower connected with this constellation is called the Gamma Normids. The display happens between 11 and 21 March with the maximum occuring around 16 March. As the Zenithal Hourly Rate (ZHR) is an average seven, it is considered a minor shower.

Extrasolar Planets in Norma

Four extrasolar planets found in this constellation up to 2009 are HD 142415 b, HD 330075 b, HD 143361 b and HD 148156 b. The orbital period given in the table below is the time the planet takes to orbit its parent star, which we know of as a year. The mass of the extrasolar planet is compared with that of Jupiter, our Solar System's largest planet, known by astronomers as the 'Jovian scale'.

HD 142415 is a yellow dwarf star of the same class and age as our own Sun. It has a planet HD 142415 b which orbits in the system's habitable zone. As a gas giant, however, it's not a candidate for the search for extra-terrestrial life.

HD 330075 b orbits its star so tightly that it is tidally locked. Effectively two of its years occur in the space of one Earth week. Being bombarded with solar radiation from such close proximity and with an estimated mean temperature of 570°C, there's no possible chance of life as we know it on this world.

HD 143361 b is a superjovian world orbiting its yellow dwarf star at a stately 2AU distance.

HD 148156 is a yellow dwarf star of the same class as our own Sun, although it has about a fifth greater mass. Its planet, HD 148156 b, is a gas giant orbiting the star in about three (Earth) years.

Extrasolar Planets Table

Star name or
catalogue number
Planet
catalogue number
Planet mass
(Jovian scale)
Orbital period
(Earth days)
Year of discoveryComments
HD 142415HD 142415 b1.623862003Gas giant; habitable zone
HD 330075HD 330075 b0.763.372004Hot Jupiter
HD 143361HD 143361 b3.121,0572008Superjovian
HD 148156HD 148156 b0.911,0102009Gas giant

Norma in Modern Culture

Norma is a girl's Christian name, the feminine of Norman. Well known Normas include Norma Jean Baker, also known as Marilyn Monroe, and Norma Major, the wife of former British Prime Minister Sir John Major.

Norma the Medical Term

'Norma lateralis' is a view of the skull from the side. If the position of viewpoint is from above and looking down, it would be called 'norma verticalis'. This is a medical term which is quite useful to know in case you ever want to impress your friends.

Norma the Opera

There is a famous opera called Norma, by Vincenzo Bellini (1801 - 1835). It was one of Maria Callas' signature roles, and is probably most famous for the aria 'Casta Diva'. The opera takes place in Gaul, in Roman times. Norma is a Druid priestess, the daughter of an arch-Druid. The theme of the opera is Norma's conflict between love and duty and inevitably ends in her death. Before the time of the opera begins, Norma has been in love with the Roman pro-consul in Gaul, and has borne him two sons, breaking her vow of chastity in doing so, although nobody suspects this. As the opera begins, our Roman has fallen for 'the younger woman' in the form of one of the virgin acolytes. The acolyte confides to Norma that she (the acolyte) has broken her vow and loves – of all things – a Roman. Norma does not yet know who the Roman is. She soon does and is hell-bent on revenge. Norma considers killing her children, but her motherly instinct prevails; she does however declare war on the Romans. Just at that moment, the pro-consul is brought in, having been captured breaking into the sacred temple. The sentence for this violation is death, but still with something in her heart for him, she offers the crowd an alternative victim – a virgin of the order who has broken her vow. She then announces to the crowd that she herself is the wrong-doer. A pyre is erected and Norma climbs up onto it. The Roman pro-consul turns face-about again and jumps onto the pyre to join her.

1Current IAU guidelines use a plus sign (+) for northern constellations and a minus sign (−) for southern ones.2A light year is the distance light travels in one year, roughly 5.88 trillion miles or 9.46 trillion km.

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