View source for Astronomy:Norma (constellation)

{{Short description|Constellation in the southern celestial hemisphere}}

{{Infobox constellation|
name = Norma |
abbreviation = Nor |
genitive = Normae |
pronounce = {{IPAc-en|ˈ|n|ɔr|m|ə}},<br>genitive {{IPAc-en|ˈ|n|ɔr|m|iː}} |
symbolism = the carpenter's square |
RA = {{RA|15|12|13.6119}} to {{RA|16|36|08.3235}}<ref name="boundary"/> |
dec= {{DEC|−42.27}} to {{DEC|−60.44}}<ref name="boundary"/> |
family = La Caille |
quadrant = SQ3 |
areatotal = 165 |
arearank = 74th |
numbermainstars = 4 |
numberbfstars = 13 |
numberstarsplanets = 4 |
numberbrightstars = 0 |
numbernearbystars = 0 |
brighteststarname = [[Astronomy:Gamma2 Normae|γ<sup>2</sup> Nor]] |
starmagnitude = 4.01 |
neareststarname = HD 145417 |
stardistancely = 44.83 |
stardistancepc = 13.75 |
numbermessierobjects = 0 |
meteorshowers = [[Astronomy:Gamma Normids|Gamma Normids]] |
bordering = [[Astronomy:Ara (constellation)|Ara]]<br />[[Astronomy:Lupus (constellation)|Lupus]]<br />Circinus<br />[[Astronomy:Triangulum Australe|Triangulum Australe]]<br />[[Astronomy:Scorpius|Scorpius]] |
latmax = 30 |
latmin = [[Earth:South Pole|90]] |
month = July |
notes=}}
'''Norma''' is a small constellation in the Southern Celestial Hemisphere between [[Astronomy:Ara (constellation)|Ara]] and [[Astronomy:Lupus (constellation)|Lupus]], one of twelve drawn up in the 18th&nbsp;century by {{wipe|France}} [[Astronomy:Astronomer|astronomer]] Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name is [[Social:Latin|Latin]] for [[Engineering:T-square|normal]], referring to a right angle, and is variously considered to represent a [[Ruler|rule]], a carpenter's square, a [[Engineering:Set square|set square]] or a [[Earth:Spirit level|level]]. It remains one of the [[Astronomy:88 modern constellations|88 modern constellations]].

Four of Norma's brighter stars—Gamma, Delta, Epsilon and Eta—make up a square in the field of faint stars. [[Astronomy:Gamma2 Normae|Gamma<sup>2</sup> Normae]] is the brightest star with an [[Astronomy:Apparent magnitude|apparent magnitude]] of 4.0. [[Astronomy:Mu Normae|Mu Normae]] is one of the most [[Astronomy:Luminosity|luminous]] stars known, with a luminosity between a quarter million and one million times that of the Sun. Four star systems are known to harbour planets. The [[Astronomy:Milky Way|Milky Way]] passes through Norma, and the constellation contains eight [[Astronomy:Open cluster|open cluster]]s visible to observers with binoculars. The constellation also hosts Abell&nbsp;3627, also called the [[Astronomy:Norma Cluster|Norma Cluster]], one of the most massive [[Astronomy:Galaxy cluster|galaxy cluster]]s known.

From the perspective of an observer on Earth, the [[Astronomy:Norma Arm|Norma Arm]] of the Milky Way passes through the constellation Norma, and it's from the constellation that the arm's name is derived.

==History==
Norma was introduced in 1751–52 by Nicolas-Louis de Lacaille with the French name ''l’Équerre et la Règle'', "the Square and Rule",<ref name=ridpathlac>{{cite web | url=http://www.ianridpath.com/startales/lacaille.html | title=Lacaille's Southern Planisphere of 1756 | work= Star Tales |author=Ridpath, Ian |publisher=Self-published | access-date= 19 March 2015}}</ref><ref>{{cite journal | author=Lacaille, Nicolas-Louis |year=1756|title= Relation abrégée du Voyage fait par ordre du Roi au cap de Bonne-espérance | journal = Mémoires de l'Académie Royale des Sciences| page=519– [589]|url= http://gallica.bnf.fr/ark:/12148/bpt6k35505/f787 |language=fr}}</ref> after he had observed and catalogued 10,000 southern stars during a two-year stay at the Cape of Good Hope. He devised 14 new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe. All but one honoured instruments that symbolised the [[Philosophy:Age of Enlightenment|Age of Enlightenment]].{{sfn|Wagman|2003|pp=6–7}}{{efn|1=The exception is [[Astronomy:Mensa (constellation)|Mensa]], named for the Table Mountain.{{sfn|Wagman|2003|pp=6–7}} }} Lacaille portrayed the constellations of Norma, [[Astronomy:Circinus|Circinus]] and [[Astronomy:Triangulum Australe|Triangulum Australe]], respectively, as a set square and ruler, a compass, and a surveyor's level in a set of draughtsman instruments, in his 1756 map of the southern stars.<ref name="ridpath">{{cite web |url=http://www.ianridpath.com/startales/lacaillenormaetc.html |last=Ridpath |first=Ian |author-link=Ian Ridpath |title=Lacaille's Grouping of Norma, Circinus, and Triangulum Australe |publisher=Self-published |access-date=27 June 2012 |work=Star Tales}}</ref> The level was dangling from the apex of a triangle, leading some astronomers to conclude he was renaming  ''l’Équerre et la Règle'' to "le Niveau", "the level".{{sfn|Wagman|2003|p=215}} In any case, the constellation's name had been shortened and Latinised by Lacaille to ''Norma'' by 1763.<ref name=ridpathlac/>

==Characteristics==
Norma is bordered by [[Astronomy:Scorpius|Scorpius]] to the north, [[Astronomy:Lupus (constellation)|Lupus]] to the northwest, Circinus to the west, Triangulum Australe to the south and Ara to the east. Covering 165.3&nbsp;square degrees and 0.401% of the night sky, it ranks 74th of the 88 constellations in size.<ref name=tirionconst>{{cite web| url=http://www.ianridpath.com/constellations2.html | title=Constellations: Lacerta–Vulpecula | work= Star Tales |author=Ridpath, Ian |publisher=Self-published | access-date= 21 March 2015}}</ref> The three-letter abbreviation for the constellation, as adopted by the [[Organization:International Astronomical Union|International Astronomical Union]] in 1922, is "Nor".<ref name="pa30_469">{{cite journal | last=Russell | first=Henry Norris |author-link=Henry Norris Russell | title=The New International Symbols for the Constellations | journal=Popular Astronomy | volume=30 | page=469 | bibcode=1922PA.....30..469R | date=1922 }}</ref> The official constellation boundaries, as set by Belgian astronomer [[Biography:Eugène Joseph Delporte|Eugène Delporte]] in 1930, are defined by a polygon of ten segments. In the [[Astronomy:Equatorial coordinate system|equatorial coordinate system]], the [[Right ascension|right ascension]] coordinates of these borders lie between {{RA|15|12|13.6119}} and {{RA|16|36|08.3235}}, while the [[Declination|declination]] coordinates are between −42.27° and −60.44°.<ref name="boundary">{{Cite journal | title=Norma, Constellation Boundary | journal=The Constellations | publisher=International Astronomical Union | url=https://www.iau.org/public/themes/constellations/#nor | access-date=21 March 2015}}</ref> The whole constellation is visible to observers south of latitude 29°N.{{efn|1=While parts of the constellation technically rise above the horizon to observers between 29°N and 48°N, stars within a few degrees of the horizon are to all intents and purposes unobservable.<ref name=tirionconst/>}}

==Features==

===Stars===
Lacaille charted and designated ten stars with the [[Astronomy:Bayer designation|Bayer designation]]s Alpha through to Mu in 1756, however his Alpha Normae was transferred into Scorpius and left unnamed by Francis Baily, before being named [[Astronomy:N Scorpii|N Scorpii]] by Benjamin Apthorp Gould, who felt its brightness warranted recognition. Though Beta Normae was depicted on his star chart, it was inadvertently left out of Lacaille's 1763 catalogue, was likewise transferred to Scorpio by Baily and named [[Astronomy:H Scorpii|H Scorpii]] by Gould.{{sfn|Wagman|2003|pp=215–16}}<!-- cites previous 3 sentences --> Norma's brightest star, [[Astronomy:Gamma2 Normae|Gamma<sup>2</sup> Normae]], is only of [[Astronomy:Apparent magnitude|magnitude]] 4.0. Overall, there are 44 stars within the constellation's borders brighter than or equal to [[Astronomy:Apparent magnitude|apparent magnitude]] 6.5.{{efn|1=Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.<ref>{{cite web|url=http://www.skyandtelescope.com/resources/darksky/3304011.html?page=1&c=y|title=The Bortle Dark-Sky Scale|last=Bortle|first=John E.|date=February 2001|work=Sky & Telescope|publisher=Sky Publishing Corporation|access-date=29 November 2014}}</ref>}}<ref name=tirionconst/>
[[Image:Constellation Norma.jpg|thumb|The constellation Norma as it can be seen by the naked eye]]

The four main stars—Gamma, Delta, Epsilon and Eta—make up a square in this region of faint stars.<ref name="streicher">{{cite journal | last = Streicher  | first = Magda  | date = 2005  | title =  Deepsky Delights: Sparkling clusters in Norma | journal = Monthly Notes of the Astronomical Society of Southern Africa |volume=64 |issue=5–6  |pages = 107–09  | bibcode=2005MNSSA..64..107S}}</ref> [[Astronomy:Gamma1 Normae|Gamma<sup>1</sup>]] and Gamma<sup>2</sup> Normae are an [[Astronomy:Double star|optical double]], and not a true [[Astronomy:Binary star|binary star]] system. Located 129 ± 1 [[Astronomy:Light-year|light-year]]s away from Earth,<ref name="vanLeeuwen2007">{{cite journal | first=F. | last=van Leeuwen | title=Validation of the New Hipparcos Reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–64 | date=2007 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | arxiv=0708.1752| s2cid=18759600 }}</ref>  Gamma<sup>2</sup>&nbsp;Normae is a yellow giant of [[Astronomy:Stellar classification|spectral type]] G8III around 2 to 2.5&nbsp;[[Astronomy:Solar mass|times as massive]] as the Sun. It has swollen to a diameter 10&nbsp;times that of the Sun and shines with 45 times the Sun's luminosity. It also is half of a close optical double, with a magnitude 10 companion star related by line of sight only.<ref name=kalergamma>{{cite web| first1=James B. | last1=Kaler | title=Gamma-2 Normae  | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/gamma2nor.html | access-date=23 March 2015}}</ref> Gamma<sup>1</sup>&nbsp;Normae is a yellow-white supergiant, located much further away at around 1500 light-years from Earth.<ref name="vanLeeuwen2007"/> [[Astronomy:Epsilon Normae|Epsilon Normae]] is a [[Astronomy:Binary star#Spectroscopic binaries|spectroscopic binary]], with two blue-white main sequence stars of almost equal mass and spectral type (B3V) orbiting each other every 3.26&nbsp;days. There is a third star separated by 22&nbsp;arcseconds, which has a magnitude of 7.5 and is likely a smaller B-type main sequence star of spectral type B9V.<ref name=ncsbo>{{cite journal |author1=Pourbaix, D. |author2=Tokovinin, A.A. |author3=Batten, A.H. |author4=Fekel, F.C. |author5=Hartkopf, W.I. |author6=Levato, H. |author7=Morell, N. I. |author8=Torres, G. |author9=Udry, S. | year=2004 | title=SB9: The Ninth Catalogue of Spectroscopic Binary Orbits | journal=Astronomy and Astrophysics | volume=424 |issue=2 | bibcode=2004A&A...424..727P | doi=10.1051/0004-6361:20041213 | pages=727–32|arxiv=astro-ph/0406573 |s2cid=119387088 }}</ref> The system is 530 ± 20&nbsp;light-years distant from Earth,<ref name="vanLeeuwen2007"/> [[Astronomy:Eta Normae|Eta Normae]] is a yellow giant of spectral type G8III with an apparent magnitude of 4.65.<ref>{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Eta+Nor&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Eta Normae |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 24 March 2015}}</ref> It shines with a [[Astronomy:Luminosity|luminosity]] approximately 66 times that of the Sun.<ref name=Mcdonald>{{cite journal|author=McDonald, I.|author2=Zijlstra, A. A.|author3=Boyer, M. L.|date=2012|title=Fundamental Parameters and Infrared Excesses of Hipparcos Stars|journal=[[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society]] |volume=427 |issue=1|pages=343–57 |bibcode=2012MNRAS.427..343M |doi=10.1111/j.1365-2966.2012.21873.x|arxiv = 1208.2037 |s2cid=118665352}}</ref>

[[Astronomy:Iota1 Normae|Iota<sup>1</sup> Normae]] is a multiple star system. The AB (mag 5.2 and 5.76) pair orbit each other with a period of 26.9&nbsp;years; they are 2.77 and 2.71&nbsp;times as massive as the Sun respectively.<ref name=malkov>{{cite journal|author1=Malkov, O. Yu. |author2=Tamazian, V.S. |author3=Docobo, J.A. |author4=Chulkov, D.A. |date=2012|title=Dynamical Masses of a Selected Sample of Orbital Binaries |journal=Astronomy and Astrophysics |volume=546|id=A69 |pages=5|doi=10.1051/0004-6361/201219774 | bibcode =2012A&A...546A..69M|doi-access=free }}</ref> The pair are 128 ± 6&nbsp;light-years distant from Earth.<ref name="vanLeeuwen2007"/> A third component is a yellow main sequence star of spectral type G8V with an apparent magnitude of 8.02.<ref name=malkov/>

[[Astronomy:Mu Normae|Mu Normae]] is a remote blue supergiant of spectral type O9.7Iab,<ref name="sota 2014">{{cite journal|author1=Sota, A. |author2=Maíz Apellániz, J. |author3=Morrell, N.I. |author4=Barbá, R.H. |author5=Walborn, N.R. |author6=Gamen, R.C. |author7=Arias, J.I. |author8=Alfaro, E.J. |date=2014|title=The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars|journal=The Astrophysical Journal Supplement|volume=211|issue=1|id=10|pages=84|doi=10.1088/0067-0049/211/1/10 |bibcode=2014ApJS..211...10S|arxiv = 1312.6222 |s2cid=118847528 }}</ref> one of the most luminous stars known, but is partially obscured by distance and [[Astronomy:Cosmic dust|cosmic dust]]. Uncertainties regarding its distance leave open the possibility that Mu Normae could be between 250,000 and one million times as luminous and up to 60&nbsp;times as massive as the Sun, though it is more likely to have around 500,000 times the Sun's luminosity and 40 times its mass.<ref name=kalermu>{{cite web| first1=James B. | last1=Kaler | title=Mu Normae  | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/munor.html | date= 30 July 2010 | access-date=19 May 2015}}</ref> It is suspected of being an [[Astronomy:Alpha Cygni variable|Alpha Cygni variable]], with a magnitude range of 4.87–4.98. [[Astronomy:QU Normae|QU Normae]] is another hot blue-white star that is a variable, ranging from magnitude 5.27 to 5.41 over 4.8 days.<ref name=AAVSOQU>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=20289 |title=QU Normae |author =Otero, Sebastian Alberto|date=24 May 2012|work=The International Variable Star Index |publisher=American Association of Variable Star Observers|access-date=12 April 2015}}</ref> Lying near [[Astronomy:Eta Normae|Eta Normae]] is [[Astronomy:R Normae|R Normae]],<ref name=arnold>{{cite book|author1=Arnold, H.J.P. |author2=Doherty, Paul |author3=Moore, Patrick |title=The Photographic Atlas of the Stars|publisher=CRC Press|location=Boca Raton, Florida|date=1999|page=176 |isbn=978-0-750-30654-6|url=https://books.google.com/books?id=YjcvJUfnWBAC&q=%22Ursa+Minor%22+variable&pg=PA148}}</ref> a [[Astronomy:Mira variable|Mira variable]]. Its visual magnitude range is 6.5–13.9 and its average period is 507.5&nbsp;days. Located halfway between Eta Normae and [[Astronomy:Gamma Circini|Gamma Circini]] is [[Astronomy:T Normae|T Normae]], another Mira variable.<ref name=arnold/>  It ranges from magnitude 6.2 to 13.6, with a period of 244&nbsp;days.<ref name=AAVSOT>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19963 |title=T Normae |author =Otero, Sebastian Alberto |date=19 March 2011 |work=The International Variable Star Index |publisher=American Association of Variable Star Observers|access-date=21 March 2015}}</ref> [[Astronomy:S Normae|S Normae]] is a well-known [[Astronomy:Cepheid variable|Cepheid variable]] with a magnitude range of 6.12–6.77 and a period of 9.75411 days.<ref name=AAVSOS>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19962 |title=S Normae |author =Watson, Christopher |date=4 January 2010|work=The International Variable Star Index |publisher=American Association of Variable Star Observers|access-date=12 March 2014}}</ref> It is located at the centre of the [[Astronomy:Open cluster|open cluster]] [[Astronomy:New General Catalogue|NGC]] 6087. It is a yellow-white supergiant of spectral type F8-G0Ib that is 6.3&nbsp;times as massive as the Sun. A binary, it has a 2.4&nbsp;[[Astronomy:Solar mass|solar mass]] ({{Solar mass|link=yes}}) companion that is a blue-white main sequence star of spectral type B9.5V.<ref name="evans13">{{cite journal|author1=Evans, Nancy Remage |author2=Bond, Howard E. |author3=Schaefer, Gail H. |author4=Mason, Brian D. |author5=Karovska, Margarita |author6=Tingle, Evan |date=2013|title=Binary Cepheids: Separations and Mass Ratios in 5M ⊙ Binaries|journal=Astronomical Journal |volume=146|issue=4|pages=93, 10 pp|arxiv=1307.7123|doi=10.1088/0004-6256/146/4/93 |bibcode = 2013AJ....146...93E |s2cid=34133110 }}</ref> A binary system composed of two wolf-rayet stars, colloquially called Apep, has been identified as a possible progenitor of a long gamma-ray burst. Located around 8000 light-years distant, it would be the first such in the Milky Way.<ref>{{cite web |last1=Weule |first1=Genelle |title=Spectacular cosmic pinwheel is a 'ticking bomb' set to blast gamma rays across the Milky Way |url=https://www.abc.net.au/news/science/2018-11-20/wolf-rayet-star-may-blast-milky-way-with-gamma-ray-burst/10506316 |website=ABC News |access-date=20 November 2018 | date=20 November 2018}}</ref>

[[Astronomy:IM Normae|IM Normae]] is one of only ten [[Astronomy:Recurrent nova|recurrent nova]]e known in the [[Astronomy:Milky Way|Milky Way]]. It has erupted in 1920 and 2002, reaching magnitude 8.5 from a baseline of 18.3. It was poorly monitored after the first eruption, so it is possible that it erupted in between.<ref>{{cite journal|last=Schaefer|first=Bradley E.|date=2010|title=Comprehensive Photometric Histories of All Known Galactic Recurrent Novae|journal=The Astrophysical Journal Supplement|volume=187|issue=2|pages=275–373|doi=10.1088/0067-0049/187/2/275 |bibcode=2010ApJS..187..275S|arxiv = 0912.4426 |s2cid=119294221}}</ref> Norma hosts two faint [[Astronomy:R Coronae Borealis variable|R Coronae Borealis variable]] stars of magnitude 10—[[Astronomy:RT Normae|RT Normae]] and [[Astronomy:RZ Normae|RZ Normae]]—rare degenerate stars thought to have formed from the merger of two [[Astronomy:White dwarf|white dwarf]]s that fade by several magnitudes periodically as they eject large amounts of carbon dust.<ref name=ASAS>{{cite arXiv|eprint=1211.2475v2|author1=Tisserand|author2=Clayton|author3=Welch|author4=Pilecki|author5=Wyrzykowski|author6=Kilkenny|title=The Ongoing Pursuit of R Coronae Borealis Stars: ASAS-3 Survey Strikes Again|class=astro-ph.SR|date=2012}}</ref> A faint object of magnitude 16, [[Astronomy:QV Normae|QV Normae]] is a high mass [[Astronomy:X-ray binary|X-ray binary]] star system 15,000–20,000 light-years distant from Earth. It is composed of a [[Astronomy:Neutron star|neutron star]] orbiting a blue-white supergiant approximately 20&nbsp;times as massive as the Sun. The [[Astronomy:Stellar wind|stellar wind]] from the more massive star is drawn to the magnetic poles of the neutron star, forming an accretion column and producing X-rays.<ref name="Hemphill 2014">{{cite journal|author1=Hemphill, Paul B. |author2=Rothschild, Richard E. |author3=Markowitz, Alex |author4=Fürst, Felix |author5=Pottschmidt, Katja |author6=Wilms, Jörn |date=2014|title=A Clumpy Stellar Wind and Luminosity-dependent Cyclotron Line Revealed by the First Suzaku Observation of the High-mass X-Ray Binary 4U 1538-522|journal=The Astrophysical Journal|volume=792|issue=1|pages=15| doi=10.1088/0004-637X/792/1/14 | bibcode=2014ApJ...792...14H|arxiv = 1407.1028 |s2cid=28693293 }}</ref> Located 19,000 light-years away,<ref name="Güver 2010"/> [[Astronomy:QX Normae|QX Normae]] is an active [[Astronomy:X-ray binary#Low-mass X-ray binary|low mass X ray binary]] composed of a neutron star and its companion star that is smaller and cooler than the Sun.<ref name="Wachter 2002">{{cite journal|author1=Wachter, Stephanie |author2=Hoard, D. W. |author3=Bailyn, Charles D. |author4=Corbel, Stephane |author5=Kaaret, Philip E. |date=2002|title=A Closer Look at the Soft X-ray Transient X1608-52 : Long-term Optical\/X-ray Observations|journal=Astrophys. J.|volume=568 |issue=2 |pages=901–11|doi=10.1086/339034|arxiv = astro-ph/0112465 |bibcode = 2002ApJ...568..901W |s2cid=13345357 }}</ref> The neutron star is 1.74 ± 0.14 times as massive as the Sun, yet its radius is a mere 9.3 ± 1.0&nbsp;km.<ref name="Güver 2010">{{cite journal|author1=Güver, Tolga |author2=Özel, Feryal |author3=Cabrera-Lavers, Antonio |author4=Wroblewski, Patricia |title=The Distance, Mass, and Radius of the Neutron Star in 4U 1608-52 | journal=The Astrophysical Journal |volume=712 |issue=2 |pages=964–73|year=2010 |doi=10.1088/0004-637X/712/2/964 |bibcode=2010ApJ...712..964G|arxiv = 0811.3979 |s2cid=15659561 }}</ref> 1E161348-5055 is a neutron star found in the centre of RCW103 [[Astronomy:Supernova remnant|supernova remnant]]. A periodic [[Physics:X-ray|X-ray]] source with a period of 6.67&nbsp;hours, it is approximately 2000 years old and 10,000 light-years away from Earth. It is unusual in that it is spinning much too slowly for its young age, behaving instead like a multi-million-year-old star.<ref>{{cite journal | first = A. | last = De Luca |author2=Caraveo, P. A.|author3= Mereghetti, S.|author4= Tiengo, A.|author5= Bignami, G. F. |date=11 August 2006 | title =A Long-Period, Violently Variable X-ray Source in a Young Supernova Remnant | journal = Science | volume = 313 | issue = 5788 | pages = 814–17 | doi = 10.1126/science.1129185 | arxiv = astro-ph/0607173 | pmid = 16825535|bibcode = 2006Sci...313..814D | s2cid = 27097399 }}</ref> [[Astronomy:SGR J1550-5418|SGR J1550-5418]] is a [[Astronomy:Soft gamma repeater|soft gamma repeater]] (SGR)—a [[Astronomy:Magnetar|magnetar]] that is emitting gamma ray flares,<ref>{{cite journal | title=Time Resolved Spectroscopy of SGR J1550-5418 Bursts Detected with Fermi/Gamma-Ray Burst Monitor |author1=Younes, G. |author2=Kouveliotou, C. |author3=van der Horst, A. J. |author4=Baring, M. G. |author5=Granot, J. |author6=Watts, A. L. |author7=Bhat, P. N. |author8=Collazzi, A. |author9=Gehrels, N. |author10=Gorgone, N. |author11=Göğüş, E. |author12=Gruber, D. |author13=Grunblatt, S. |author14=Huppenkothen, D. |author15=Kaneko, Y. |author16=von Kienlin, A. |author17=van der Klis, M. |author18=Lin, L. |author19=Mcenery, J. |author20=van Putten, T. |author21=Wijers, R. A. M. J. |name-list-style=amp | journal= The Astrophysical Journal| volume=785| issue=1| id=52| pages=11 |year=2014 | doi = 10.1088/0004-637X/785/1/52 | bibcode=2014ApJ...785...52Y |arxiv = 1402.6015 |hdl=1911/75890 |s2cid=53486907 | url=https://pure.uva.nl/ws/files/2181967/156763_Time_Resolved_Spectroscopy.pdf}}</ref> located some 30,000 light-years distant from Earth. The rotation period, of approximately 2.07 seconds, is the fastest yet observed for a magnetar.<ref>{{cite web|url=http://www.spaceflightnow.com/news/n0902/10gammarays/|title=ESA News Release: Swift, Fermi probe fireworks from flaring gamma-ray star|date=10 February 2009|work=Spaceflight Now|access-date=20 May 2015}}</ref><!-- cites previous two sentences --> [[Astronomy:XTE J1550-564|XTE J1550-564]] is another X-ray binary, this time composed of a large black hole around 10 times as massive as the Sun and a cool orange donor star. The black hole is a [[Astronomy:X-ray binary#Microquasar|microquasar]], firing off [[Astronomy:Astrophysical jet|jets]] of material most likely from its accretion disk.<ref name="Steiner 2011">{{cite journal|author1=Steiner, James F. |author2=Reis, Rubens C. |author3=McClintock, Jeffrey E. |author4=Narayan, Ramesh |author5=Remillard, Ronald A. |author6=Orosz, Jerome A. |author7=Gou, Lijun |author8=Fabian, Andrew C. |author9=Torres, Manuel A. P. |date=2011|title=The spin of the black hole microquasar XTE J1550-564 via the continuum-fitting and Fe-line methods|journal=Monthly Notices of the Royal Astronomical Society|volume=416|issue=2|pages=941–58 | doi=10.1111/j.1365-2966.2011.19089.x |bibcode=2011MNRAS.416..941S|arxiv = 1010.1013 |s2cid=53399981 }}</ref>
=== Exoplanets ===
Four star systems are known to harbour planets. [[Astronomy:HD 330075|HD 330075]] is a sunlike star around 164&nbsp;light-years distant that is orbited by a [[Astronomy:Hot Jupiter|hot Jupiter]] every 3.4&nbsp;days. Announced in 2004, it was the first planet discovered by the HARPS [[Astronomy:Spectrograph|spectrograph]].<ref name="Pepe2004">{{ cite journal | url=http://www.aanda.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/aa/full/2004/31/aa0389-04/aa0389-04.html | title=The HARPS search for southern extra-solar planets I. HD 330075 b: A new 'hot Jupiter' | last1=Pepe | first1=F. | last2=Mayor | first2=M. | last3=Queloz | first3=D. | last4=Benz | first4=W. | last5=Bonfils | first5=X. | last6=Bouchy | first6=F. | last7=Lo Curto | first7=G. | last8=Lovis | first8=C. | last9=Mégevand | first9=D. | journal=Astronomy and Astrophysics | volume=423 | issue=1 | pages=385–89 | year=2004 | arxiv=astro-ph/0405252 | bibcode=2004A&A...423..385P | doi=10.1051/0004-6361:20040389 | s2cid=59157984 }}</ref> [[Astronomy:HD 148156|HD 148156]] is a star 168 ± 7 light-years distant. Slightly larger and hotter than the Sun, it was found to have a roughly Jupiter-size planet with an orbital period of 2.8 years.<ref name="Naef2010">{{cite journal |doi=10.1051/0004-6361/200913616 |title=The HARPS Search for Southern Extrasolar Planets XXIII. 8 Planetary Companions to Low-activity Solar-type Stars |last1=Naef |first1=Dominique |last2=Mayor |first2=Michel |last3=Lo Curto |first3=Gaspare |last4=Bouchy |first4=François |last5=Lovis |first5=Christophe |last6=Moutou |first6=Claire |last7=Benz |first7=Willy |last8=Pepe |first8=Francesco |last9=Queloz |first9=Didier |last10=Santos |first10=Nuno C. |last11=Ségransan |first11=Damien |last12=Udry |first12=Stéphane |last13=Bonfils |first13=Xavier |last14=Delfosse |first14=Xavier |last15=Forveille |first15=Thierry |last16=Hébrard |first16=Guillaume |last17=Mordasini |first17=Christoph |last18=Perrier |first18=Christian |last19=Boisse |first19=Isabelle |last20=Sosnowska |first20=Danuta |journal=Astronomy and Astrophysics |volume=523 |page=A15 |year=2010 |arxiv=1008.4600 |bibcode=2010A&A...523A..15N |s2cid=118845989 |url=http://www.aanda.org/articles/aa/full_html/2010/15/aa13616-09/aa13616-09.html }}</ref> [[Astronomy:HD 143361|HD 143361]] is a binary star system composed of a sunlike star and a faint red dwarf separated by 30.9&nbsp;AU. A planet roughly triple the mass of Jupiter orbits the brighter star every 1057± 20&nbsp;days.<ref name="MAGELLAN">{{cite journal | last1=Minniti | first1=Dante | last2=Butler | first2=R. Paul | last3=López-Morales | first3=Mercedes | last4=Shectman | first4=Stephen A. | last5=Adams | first5=Fred C. | last6=Arriagada | first6=Pamela | last7=Boss | first7=Alan P. | last8=Chambers | first8=John E. | title=Low-Mass Companions for Five Solar-Type Stars From the Magellan Planet Search Program | journal=[[Astronomy:The Astrophysical Journal|The Astrophysical Journal]] | date=2009 | volume=693 | issue=2 | pages=1424–30 | doi=10.1088/0004-637X/693/2/1424 | bibcode=2009ApJ...693.1424M |arxiv = 0810.5348 | s2cid=119224845 }}</ref> [[Astronomy:HD 142415|HD 142415]] is approximately 113&nbsp;light-years distant and has a Jupiter-sized planet with an orbital period of around 386 days.<ref name="Mayor2004">{{cite journal | url=http://www.aanda.org/articles/aa/full/2004/07/aa0250/aa0250.html | title=The CORALIE Survey for Southern Extra-solar Planets XII. Orbital Solutions for 16 Extra-solar Planets Discovered with CORALIE  | last1=Mayor | first1=M. | last2=Udry | first2=S. | last3=Naef | first3=D. | last4=Pepe | first4=F. | last5=Queloz | first5=D. | last6=Santos | first6=N. C. | last7=Burnet | first7=M. | journal=Astronomy and Astrophysics | volume=415 | issue=1 | pages=391–402 | year=2004 | arxiv=astro-ph/0310316 | bibcode=2004A&A...415..391M | doi=10.1051/0004-6361:20034250 | s2cid=5233877 }}</ref><!-- cites previous two sentences -->

===Deep-sky objects===
[[File:Ant Nebula.jpg|thumb|right|The Ant Nebula, Mz 3, viewed with the Hubble Space Telescope]]
Due to its location on the Milky Way, this constellation contains many [[Astronomy:Deep-sky object|deep-sky object]]s such as [[Astronomy:Star cluster|star cluster]]s,<ref name=arnold/> including eight [[Astronomy:Open cluster|open cluster]]s visible through binoculars.<ref name=mobberly>{{cite book|last=Mobberly|first=Martin|title=The Caldwell Objects and How to Observe Them|url=https://books.google.com/books?id=amPrWoOWgHcC&pg=PA186|year=2009|publisher=Springer|location=New York, New York|isbn=978-1-4419-0325-9|pages=186–87}}</ref> [[Astronomy:NGC 6087|NGC 6087]] is the brightest of the [[Astronomy:Open cluster|open cluster]]s in Norma with a magnitude of 5.4. It lies in the southeastern corner of the constellation between [[Astronomy:Alpha Centauri|Alpha Centauri]] and [[Astronomy:Zeta Arae|Zeta Arae]]. Thought to be around 100 million years old, it is about 3300 light-years away and is around 14&nbsp;light-years in diameter. Its brightest member is the [[Astronomy:Cepheid variable|Cepheid variable]] [[Astronomy:S Normae|S Normae]].<ref name=mobberly/> A rich background star field makes it less distinct, though around 36 member stars are visible though a 10&nbsp;cm telescope at 150x magnification.<ref name=bakich2010/> Located 0.4° north of [[Astronomy:Kappa Normae|Kappa Normae]] is [[Astronomy:NGC 6067|NGC 6067]], which has an integrated magnitude of 5.6 though it is indistinct as it lies in a rich star field.<ref name=bakich2010>{{cite book | first=Michael E. | last=Bakich | date=2010 | pages=190–91 | title=1001 Celestial Wonders to See Before You Die: The Best Sky Objects for Star Gazers  |url=https://books.google.com/books?id=qEhpS7d5ZdAC&pg=PA191 | series=Patrick Moore's Practical Astronomy Series | publisher=Springer |location= New York, New York | isbn=978-1-4419-1777-5}}</ref>  It is thought to be around 102 million years old, and contain 891&nbsp;solar masses.<ref name=aaa477_1_165>{{cite journal |author1=Piskunov, A. E. |author2=Schilbach, E. |author3=Kharchenko, N. V. |author4=Röser, S. |author5=Scholz, R.-D. | title=Tidal Radii and Masses of Open Clusters | journal=Astronomy and Astrophysics | volume=477 | issue=1 | date=January 1, 2008 | pages=165–172 | doi=10.1051/0004-6361:20078525 | bibcode=2008A&A...477..165P | doi-access=free }}</ref> Two Cepheid variables—QZ Normae and V340 Normae—have been identified as members of the cluster.<ref name=majaess>{{cite journal|author1=Majaess, D. |author2=Sturch, L. |author3=Moni Bidin, C. |author4=Soto, M. |author5=Gieren, W. |author6=Cohen, R. |author7=Mauro, F. |author8=Geisler, D. |author9=Bonatto, C. |author10=Borissova, J. |author11=Minniti, D. |author12=Turner, D. |author13=Lane, D. |author14=Madore, B. |author15=Carraro, G. |author16=Berdnikov, L. |title=Anchors for the Cosmic Distance Scale: the Cepheid QZ Normae in the Open Cluster NGC 6067|journal=Astrophysics and Space Science|volume=347|issue=1|pages=61–70|date=August 2013|doi=10.1007/s10509-013-1495-1 |bibcode=2013Ap&SS.347...61M|arxiv=1305.3914|s2cid=119207107 }}</ref> Fainter open clusters include [[Astronomy:NGC 6134|NGC 6134]] with a combined magnitude of 7.2 and located 4000 light-years away from Earth, the spread-out [[Astronomy:NGC 6167|NGC 6167]] of magnitude 6.7, [[Astronomy:NGC 6115|NGC 6115]] near Gamma Normae, [[Astronomy:NGC 6031|NGC 6031]] and [[Astronomy:NGC 5999|NGC 5999]].<ref name="streicher"/>

[[File:View Towards the Great Attractor.jpg|thumb|right|Galaxies of the Norma Cluster (yellow) in a 0.5° x 0.5° field]]
Located around 4900 light-years distant is [[Astronomy:Shapley 1|Shapley 1]] (or PK&nbsp;329+02.1), a [[Astronomy:Planetary nebula|planetary nebula]] better known as the ''Fine-Ring Nebula''. Appearing ring-shaped, it is thought that it actually is cylindrical and oriented directly at Earth.  Around 8700 years old,<ref name="Jones 2012">{{cite journal|author1=Jones, D. |author2=Mitchell, D. L. |author3=Lloyd, M. |author4=Pollacco, D. |author5=O'Brien, T. J. |author6=Meaburn, J. |author7=Vaytet, N. M. H. |date=2012|title=The Morphology and Kinematics of the Fine Ring Nebula, Planetary Nebula Sp 1, and the Shaping Influence of its Binary Central Star|journal=Monthly Notices of the Royal Astronomical Society|volume=420|issue=3|pages=2271–79 | doi=10.1111/j.1365-2966.2011.20192.x |bibcode=2012MNRAS.420.2271J|arxiv = 1111.2860 |s2cid=119164201 }}</ref> it lies about five degrees west-northwest of Gamma<sup>1</sup>&nbsp;Normae. Its integrated magnitude is 13.6 and its mean [[Astronomy:Surface brightness|surface brightness]] is 13.9. The central star is a [[Astronomy:White dwarf|white dwarf]] of magnitude 14.03. [[Astronomy:Mz 1|Mz 1]] is a [[Astronomy:Bipolar nebula|bipolar]] planetary nebula, thought to be an hourglass shape tilted at an angle to observers on Earth, some 3500 light-years distant.<ref>{{cite journal | last1 = Monteiro | first1 = Hektor | last2 = Schwarz | first2 = Hugo E. | last3 = Gruenwald | first3 = Ruth | last4 = Guenthner | first4 = Katherine | last5 = Heathcote | first5 = Steve R. | title = Three-Dimensional Photoionization Structure and Distances of Planetary Nebulae. II. Menzel 1 | journal = The Astrophysical Journal | date = 2005 | volume = 620 | issue = 1 | pages = 321–29 | bibcode = 2005ApJ...620..321M | doi = 10.1086/426809 |arxiv = astro-ph/0410496 | s2cid = 119442827 }}</ref> [[Astronomy:Mz 3|Mz 3]]—known as the Ant Nebula as it resembles an ant—has a complex appearance, with at least four outflow jets and two large lobes visible.<ref>{{cite journal | last1 = Santander-García | first1 = M. | last2 = Corradi | first2 = R. L. M. | last3 = Balick | first3 = B. | last4 = Mampaso | first4 = A. | title = Menzel 3: Dissecting the Ant | journal = Astronomy and Astrophysics | date = 2004 | volume = 426 | issue = 1 | pages = 185–94 | bibcode = 2004A&A...426..185S | doi = 10.1051/0004-6361:20041147|arxiv = astro-ph/0406551 | s2cid = 2203000 }}</ref>

Approximately 200 million light-years from Earth with a [[Astronomy:Redshift|redshift]] of 0.016 is Abell 3627; also called the [[Astronomy:Norma Cluster|Norma Cluster]], it is one of the most massive [[Astronomy:Galaxy cluster|galaxy cluster]]s known to exist, at ten times the average cluster mass. Abell 3627 is thus theorized to be the [[Astronomy:Great Attractor|Great Attractor]], a massive object that is pulling the [[Astronomy:Local Group|Local Group]], the [[Astronomy:Virgo Supercluster|Virgo Supercluster]], and the [[Astronomy:Hydra–Centaurus Supercluster|Hydra–Centaurus Supercluster]] towards its location at 600–1000 kilometres per second.<ref>{{cite book |title = 300 Astronomical Objects: A Visual Reference to the Universe |last1=Wilkins |first1=Jamie |last2=Dunn |first2 = Robert |publisher = Firefly Books |year = 2006 |isbn = 978-1-55407-175-3}}</ref>
{{-}}

==Meteor shower==
The relatively weak meteor shower [[Astronomy:Gamma Normids|Gamma Normids]] (GNO), which is typically active from March 7 to 23, peaking on March 15, has its [[Astronomy:Radiant (meteor shower)|radiant]] near [[Astronomy:Gamma2 Normae|Gamma<sup>2</sup> Normae]].<ref name=AMS>{{cite web |last1=Lunsford |first1=Robert |title=Meteor Activity Outlook for March 21-27, 2015 |url=http://www.amsmeteors.org/2015/03/meteor-activity-outlook-for-march-21-27-2015/ |website=American Meteor Society |access-date=28 August 2015 |archive-url=https://web.archive.org/web/20150908121834/http://www.amsmeteors.org/2015/03/meteor-activity-outlook-for-march-21-27-2015/ |archive-date=8 September 2015 |url-status=dead }}</ref>
== Galactic Arm ==
[[Image:Milky Way Arms ssc2008-10.svg|300px|right|thumb|Diagram of the Milky Way's spiral arms]]
The [[Astronomy:Norma Arm|Norma Arm]] is a minor galactic arm named after Norma for lying in its background.
{{Clear}}

==Notes==
{{notelist}}

==References==
{{Reflist}}

===Sources===
{{Commons and category|Norma|Norma (constellation)}}
{{refbegin}}
* {{cite book
  | last = Wagman
  | first = Morton
  | year = 2003
  | title = Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others
  | publisher = The McDonald & Woodward Publishing Company
  | location = Blacksburg, Virginia
  | isbn = 978-0-939923-78-6
  }}
{{refend}}

== External links ==
* [http://astrojan.nhely.hu/norma.htm The clickable Norma]

{{Stars of Norma}}
{{navconstel}}
{{ConstellationsByLacaille}}
{{Sky|16|03|00|-|52|00|36|10}}

{{DEFAULTSORT:Norma (constellation)}}
[[Category:Norma (constellation)| ]]
[[Category:Constellations]]
[[Category:Southern constellations]]
[[Category:Constellations listed by Lacaille]]

{{Sourceattribution|Norma (constellation)}}