Norma (constellation)

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Norma
Constellation
Norma
Abbreviation Nor
Genitive Normae
Pronunciation /ˈnɔrmə/,
genitive /ˈnɔrm/
Symbolism the carpenter's square
Right ascension 16.05
Declination −52.01
Family La Caille
Quadrant SQ3
Area 165 sq. deg. (74th)
Main stars 2
Bayer/Flamsteed
stars
13
Stars with planets 4
Stars brighter than 3.00m 0
Stars within 10.00 pc (32.62 ly) 0
Brightest star γ2 Nor (4.01m)
Nearest star HD 145417
(44.83 ly, 13.75 pc)
Messier objects 0
Meteor showers Gamma Normids
Bordering
constellations
Scorpius
Lupus
Circinus
Triangulum Australe
Ara
Visible at latitudes between +30° and −90°.
Best visible at 21:00 (9 p.m.) during the month of July.

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.

History[edit]

Norma, originally named l’Equerre et la Regle in French, was one of the constellations invented by Abbé de Lacaille in the middle of the 1750s, when he was measuring about 10,000 stars at the Cape of Good Hope.[1] Norma represents a carpenter's square, used in the Age of Exploration by carpenters on exploratory vessels.[2]

Notable features[edit]

The constellation Norma as it can be seen by the naked eye.

Stars[edit]

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:

  • 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).
  • 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.
  • R Normae is a Mira variable. Its visual range is 6.5–13.9 and its average period is 507.5 days.

Deep-sky objects[edit]

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.
  • Sp 1 (or PK 329+02.1) is a planetary nebula better known as the Fine-Ring Nebula. It lies about five degrees west-northwest of γ1 Nor, though its actual distance has been variously estimated at 1000–4700 ly. Its integrated magnitude is 13.6 and its mean surface brightness is 13.9. The central star is a white dwarf of mag 14.03.

References[edit]

Citations
  1. ^ Ridpath, Ian. "Norma". Star Tales. Retrieved 9 July 2012. 
  2. ^ Staal 1988, p. 254.
  3. ^ Watson, Christopher (4 January 2010). "S Normae". AAVSO Website. American Association of Variable Star Observers. Retrieved 12 March 2014. 
  4. ^ Wilkins & Dunn 2006.
References
  • Burnham, Robert Jr. (1978), Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System (2nd ed.), General Publishing Company, Ltd., ISBN 0-486-23568-8 
  • Ridpath, Ian; Tirion, Wil (2007), Stars and Planets Guide, Princeton University Press, ISBN 978-0-691-13556-4 
  • Staal, Julius D.W. (1988), The New Patterns in the Sky: Myths and Legends of the Stars, The McDonald and Woodward Publishing Company, ISBN 0-939923-04-1 
  • Wilkins, Jamie; Dunn, Robert (2006), 300 Astronomical Objects: A Visual Reference to the Universe, Firefly Books, ISBN 978-1-55407-175-3 

External links[edit]

Coordinates: Sky map 16h 03m 00s, −52° 00′ 36″