Musca#History

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

{{about|the southern constellation|the fly genus|Musca (fly)|other uses}}

{{Infobox constellation

| name = Musca

| abbreviation = Mus

| genitive = Muscae

| pronounce =

{{plainlist |

{{IPAc-en|ˈ|m|ʌ|s|k|ə}}
genitive {{IPAc-en|ˈ|m|ʌ|s|iː}}

}}

| symbolism = the Fly

| RA = {{RA|11|19.3}} to {{RA|13|51.1}}

| dec = −64.64° to −75.68°

| family = Bayer

| quadrant = SQ3

| areatotal = 138

| arearank = 77th

| numbermainstars = 6

| numberbfstars = 13

| numberstarsplanets = 3

| numberbrightstars = 1

| numbernearbystars = 1

| brighteststarname = α Mus

| starmagnitude = 2.69

| neareststarname = LP 145-141

| stardistancely = 15.07

| stardistancepc = 4.62

| numbermessierobjects = 0

| meteorshowers =

| bordering =

{{plainlist |

}}

| latmax = 10

| latmin = 90

| month = May

| notes =

}}

{{Language with name/for|la|Musca|the fly}} is a small constellation in the deep southern sky. It was one of 12 constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman, and it first appeared on a celestial globe {{Convert|35|cm|in|abbr=on}} in diameter published in 1597 (or 1598) in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. It was also known as {{Language with name/for|la|Apis|the bee|links=no}} for 200 years. Musca remains below the horizon for most Northern Hemisphere observers.

Many of the constellation's brighter stars are members of the Scorpius–Centaurus association, a loose group of hot blue-white stars that appears to share a common origin and motion across the Milky Way. These include Alpha, Beta, Gamma, Zeta² and (probably) Eta Muscae, as well as HD 100546, a blue-white Herbig Ae/Be star that is surrounded by a complex debris disk containing a large planet or brown dwarf and possible protoplanet. Two further star systems have been found to have planets. The constellation also contains two cepheid variables visible to the naked eye. Theta Muscae is a triple star system, the brightest member of which is a Wolf–Rayet star.

History

File:BayerMusca.jpg of 1603]]

Musca was one of the 12 constellations established by the astronomer Petrus Plancius from the observations of the southern sky by the Dutch explorers Pieter Dirkszoon Keyser and Frederick de Houtman, who had sailed on the first Dutch trading expedition, known as the Eerste Schipvaart, to the East Indies. De Houtman included it in his southern star catalogue in 1598 under the Dutch name De Vlieghe, "The Fly".{{cite web| url=http://www.ianridpath.com/startales/startales1c.html#houtman | title=Frederick de Houtman's Catalogue|last1=Ridpath|first1=Ian|publisher=self-published |work=Star Tales | access-date= 20 December 2013}} They assigned four stars to the constellation, with a star that would be later designated as Beta Muscae marking the head, Gamma the body, and Alpha and Delta the left and right wings, respectively.{{cite journal | title = On Frederick de Houtman's Catalogue of Southern Stars, and the Origin of the Southern Constellations | author= Knobel, Edward B. | author-link= Edward Knobel |journal = Monthly Notices of the Royal Astronomical Society | volume= 77| issue= 5 | pages=414–32 [426] | bibcode = 1917MNRAS..77..414K |date=1917 | doi=10.1093/mnras/77.5.414| doi-access= free }} It first appeared on a 35-cm-diameter (14-in) celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius, though was unnamed. The first depiction of this constellation in a celestial atlas was in the German cartographer Johann Bayer's Uranometria of 1603,{{cite web| url=http://www.ianridpath.com/startales/bayer-southern.html | title=Johann Bayer's Southern Star Chart|last1=Ridpath|first1=Ian|author-link=Ian Ridpath|publisher=self-published |work=Star Tales | access-date= 20 December 2013}} though Bayer termed it Apis— "the Bee", a name by which it was known for the next two centuries. A 1603 celestial globe by Willem Blaeu depicts it as providing nourishment for the nearby constellation Chamaeleon—its tongue trying to catch the insect.{{cite web| url=http://www.ianridpath.com/startales/musca.html | title=Musca |last1=Ridpath|first1=Ian|publisher=self-published |work=Star Tales | access-date= 20 December 2013}}

The French explorer and astronomer Nicolas Louis de Lacaille called it la Mouche on the 1756 version of his planisphere of the southern skies. Jean Fortin retained the French name in 1776 for his Atlas Céleste, while Lacaille latinised the name for his revised Coelum Australe Stelliferum in 1763.{{cite web| url=http://www.ianridpath.com/startales/lacaille.html | title=Lacaille's Southern Planisphere of 1756|last1=Ridpath|first1=Ian|author-link=Ian Ridpath|publisher=self-published |work=Star Tales | access-date= 20 December 2013}} Lacaille renamed it to Musca Australis, the Southern Fly—Australis, since it counterparted the now discarded constellation of Musca Borealis composed of a few stars in Aries, and to avoid confusion with Apus. Today, the name is simply Musca. It is the only official constellation depicting an insect.{{cite web | last = Streicher | first = Magda | date = April 2006 | title = Musca—The Heavenly Fly | publisher = The Astronomical Society of Southern Africa | work = Deepsky Delights | url =http://www.mnassa.org.za/html/Apr2006/2006MNASSA..65..Apr..56.pdf |pages = 56–59 | access-date = 21 November 2013}}

The Kalapalo people of Mato Grosso state in Brazil called Alpha and Beta Muscae (along with Beta and Kappa Crucis) Kutsu anangagï "Ornate Hawk-Eagle's double flutes".{{cite book|last=Basso|first=Ellen B. |title=In Favor of Deceit: A Study of Tricksters in an Amazonian Society|publisher=University of Arizona Press|location=Tucson, Arizona|date=1987|page=[https://archive.org/details/infavorofdeceits0000bass/page/360 360]|isbn=0-8165-1022-9|url=https://archive.org/details/infavorofdeceits0000bass|url-access=registration}} The Wardaman people of the Northern Territory in Australia perceived the main stars of Musca as a ceremonial boomerang, part of the Central Arena—a sacred area surrounding the constellation Crux that depicts the lightning creation beings and where they teach Wardaman customs; Alpha and Beta also signified a ceremonial headband, while Gamma and Delta represented two armbands.{{cite book | last1 = Harney | first1 = Bill Yidumduma | last2 = Cairns | first2 = Hugh C. | title = Dark Sparklers | publisher = Hugh C. Cairns | location = Merimbula, New South Wales | date = 2004 | orig-year = 2003 | edition = Revised | isbn = 0-9750908-0-1 |pages=202, 208}} In central Australia, the Arrernte and Luritja peoples living in on a mission in Hermannsburg viewed the sky as divided between them, east of the Milky Way representing Arrernte camps and west denoting Luritja camps. The stars of Musca, along with Fomalhaut, Alpha Pavonis, and Alpha and Beta Gruis, were all claimed by the Arrernte.{{cite book|last=Johnson|first=Diane|title=Night skies of aboriginal Australia: a noctuary|publisher=University of Sydney|location=Darlington, New South Wales|date=1998|pages=[https://archive.org/details/nightskiesofabor0000john/page/70 70–72]|isbn=1-86451-356-X|url-access=registration|url=https://archive.org/details/nightskiesofabor0000john/page/70}}

Characteristics

Musca is bordered by Crux to the north, Carina to the west, Chamaeleon to the south, Apus and Circinus to the east, and Centaurus to the northeast. Covering 138 square degrees and 0.335% of the night sky, it ranks 77th of the 88 constellations in size.{{cite book |last=Bagnall |first=Philip M. |title=The Star Atlas Companion: What You Need to Know about the Constellations |publisher=Springer |location=New York, New York |date=2012 |isbn=978-1-4614-0830-7 |pages=303–07|url=https://books.google.com/books?id=KcIg02TKW6QC&pg=PA303}} The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Mus".{{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 }} The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of six segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between {{RA|11|19.3}} and {{RA|13|51.1}}, while the declination coordinates are between −64.64° and −75.68°.{{Cite journal | title=Musca, Constellation Boundary | journal=The Constellations | publisher=International Astronomical Union | url=http://www.iau.org/public/constellations/#mus | access-date=19 December 2013 }} The whole constellation is visible to observers south of latitude 14°N.{{cite web| url=http://www.ianridpath.com/constellations2.html | title=Constellations: Lacerta–Vulpecula | work= Star Tales |author=Ian Ridpath |author-link=Ian Ridpath|publisher=self-published | access-date= 24 June 2014}}{{efn|1=While parts of the constellation technically rise above the horizon to observers between 14°N and 25°N, stars within a few degrees of the horizon are essentially unobservable.}}

Features

=Stars=

Image:Constellation Musca.jpg

Lacaille charted and designated 10 stars with the Bayer designations Alpha to Kappa in 1756. He catalogued stars that became Lambda and Mu, but did not designate them as he considered them informes as they lay outside the asterism proper. Francis Baily considered them part of Musca, and Gould gave them their Bayer designations. Baily also dropped Kappa, which he felt was too faint to warrant a name, and designated two adjacent stars as Zeta¹ and Zeta². These last two stars are 1° apart, quite far to be sharing a Bayer designation. Lacaille had originally labelled the fainter one as Zeta, while Baily presupposed he had meant to label the brighter one. Reluctant to remove Lacaille's designation, he gave them both the Zeta designation.{{cite book | last = Wagman | first = Morton | date = 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 |pages=213–14}} Altogether there are 62 stars brighter than magnitude 6.5 in the constellation.

The pattern of the brightest stars resembles that of Ursa Minor, in that the stars form a pattern reminiscent of a bowl with a handle. Lying south-southeast of Acrux in neighbouring Crux is Alpha Muscae.{{cite book|last=Motz|first=Lloyd|author2=Nathanson, Carol|title=The Constellations: An Enthusiast's Guide to the Night Sky|publisher=Aurum Press|location=London, United Kingdom|date=1991|pages=385–86|isbn=978-1-85410-088-7}} It is the brightest star in the constellation with an apparent magnitude of 2.7. Lying around 310 light-years away, it is a blue-white star of spectral type B2IV-V that is around 4520 times as luminous and 8 times as massive as the Sun. The star is a Beta Cephei variable with about 4.7 times the Sun's diameter, and pulsates every 2.2 hours, varying by 1% in brightness. A nearby star of magnitude 13 may or may not be a companion star.{{cite web|url=http://stars.astro.illinois.edu/sow/alphamus.html |title=Alpha Muscae |last=Kaler|first=Jim|author-link= James B. Kaler |work=Stars|publisher=University of Illinois|access-date=21 December 2013}} Marking the fly's tail is Gamma Muscae, a blue-white star of spectral type B5V that varies between magnitudes 3.84 and 3.86 over a period of 2.7 days. It is a variable of a different type, classed as a slowly pulsating B star, a type of variable.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19956 |title=Gamma Muscae |author=Otero, Sebastian Alberto |date=5 March 2012|work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=21 December 2013}} It is around five times as massive as the Sun.{{cite journal|author =Molenda-Zakowicz, J. |author2 =Połubek, G.|date=2004|title=Empirical Absolute Magnitudes, Luminosities and Effective Temperatures of SPB Variables and the Problem of Variability Classification of Monoperiodic Stars|journal=Acta Astronomica|volume=54|pages=281–97 [283]|url=http://acta.astrouw.edu.pl/Vol54/n3/pap_54_3_4.pdf|bibcode = 2004AcA....54..281M }}

Beta Muscae is a binary star system around 341 light-years distant that is composed of two blue-white main-sequence stars of spectral types B2V and B3V that orbit each other every 194 years. They are eight and six times as massive as the Sun, respectively, and have about 3.5 times its diameter.{{cite web|url=http://stars.astro.illinois.edu/sow/betamus.html |title=Beta Muscae |last=Kaler|first=Jim|author-link= James B. Kaler |work=Stars|publisher=University of Illinois|date=22 June 2010| access-date=23 December 2013}} Zeta² Muscae is a white main sequence star of spectral type A5V around 330 light-years distant from Earth.{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=zeta2+mus&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = HR 4703 – Star in Double System |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 25 December 2013}} It is part of a triple star system with faint companions at 0.5 and 32.4 arc seconds distance.{{cite journal|author=Chen, Christine H. |display-authors=4 |author2=Pecaut, Mark |author3=Mamajek, Eric E. |author4=Su, Kate Y. L. |author5=Bitner, Martin |date=2012|title=A Spitzer MIPS Study of {{Solar mass|2.5–2.0}} Stars in Scorpius-Centaurus|journal=The Astrophysical Journal|volume=756|issue=2|pages=133–57|arxiv=1207.3415|doi=10.1088/0004-637x/756/2/133|bibcode = 2012ApJ...756..133C |s2cid=119278056 }} Eta Muscae is a multiple star system, the two main components forming an eclipsing binary that has a combined spectral type of B8V and magnitude of 4.77 that dips by 0.05 magnitude every 2.39 days.{{cite journal|author=Zasche, P. |display-authors=4 |author2=Wolf, M. |author3=Hartkopf, W. I. |author4=Svoboda, P. |author5=Uhlař, R. |author6=Liakos, A. |author7=Gazeas, K.|date=2009|title=A Catalog of Visual Double and Multiple Stars with Eclipsing Components|journal=The Astronomical Journal|volume=138|issue=2|pages=664–79|doi=10.1088/0004-6256/138/2/664|arxiv = 0907.5172 |bibcode = 2009AJ....138..664Z |s2cid=17089387 }} Alpha, Beta, Gamma, HD 103079, Zeta² and (likely) Eta are all members of the Lower Centaurus Crux subgroup of the Scorpius–Centaurus association, a group of predominantly hot blue-white stars that share a common origin and proper motion across the galaxy.{{cite journal|title=A Hipparcos Census of Nearby OB Associations|author=de Zeeuw, P.T. |display-authors=4 |author2=Hoogerwerf, R. |author3=de Bruijne, J.H.J. |author4=Brown, A.G.A. |author5=Blaauw, A.|date=1999|journal=Astronomical Journal|volume=117|issue=1|pages=354–99|bibcode=1999AJ....117..354D|doi=10.1086/300682|arxiv = astro-ph/9809227 |s2cid=16098861 }}{{citation | last1=de Geus | first1=E. J. | last2=de Zeeuw | first2=P. T. | last3=Lub | first3=J. | title=Physical Parameters of Stars in the Scorpio-Centaurus OB Association | journal=Astronomy and Astrophysics | volume=216 | issue=1–2 | pages=44–61 |date=June 1989 | bibcode=1989A&A...216...44D }}

Delta and Epsilon mark the fly's left wing and right wing, respectively. With an apparent magnitude of 3.62, Delta is an orange giant of spectral type K2III located around 91 light-years away.{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=del+Mus |title = Delta Muscae |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 25 December 2013}} Epsilon Muscae is a red giant of spectral type M5III and semiregular variable that ranges between magnitudes 3.99 and 4.31 over approximately 40 days.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19957 |title=Epsilon Muscae |author=Watson, Christopher |date=25 August 2009|work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=21 December 2013}} It has expanded to 130 times the Sun's diameter and 1800 to 2300 its luminosity. It was a star originally 1.5 to 2 times as massive as the Sun. Although of a similar distance—around 302 light-years—to the stars of the Lower Centaurus Crux subgroup, it is moving much faster at around 100 km/s and does not share a common origin.{{cite web|url=http://stars.astro.illinois.edu/sow/epsmus.html |title=Epsilon Muscae |last=Kaler|first=Jim|author-link= James B. Kaler |work=Stars|publisher=University of Illinois|access-date=21 December 2013}} To the northwest lies Mu Muscae, an orange giant of spectral type K4III that varies between apparent magnitude 4.71 and 4.76, and has been classified as a slow, irregular variable.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19960 |title=Mu Muscae |author=Otero, Sebastian Alberto |date=31 October 2011|work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=21 January 2014}} Near Mu is Lambda Muscae, the third-brightest star in the constellation and a white main-sequence star of spectral type A7V around 128 light-years distant from Earth.{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?submit=display&bibdisplay=refsum&bibyear1=2009&bibyear2=2014&Ident=%403269938&Name=*+lam+Mus#lab_bib |title = Lambda Muscae – Star in Double System |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 25 December 2013}}

Located near Alpha is R Muscae, a classical Cepheid variable ranging from apparent magnitude 5.93 to 6.73 over 7.5 days. It is a yellow-white supergiant ranging between spectral types F7Ib and G2Ib,{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19677 |title=R Muscae |author=Watson, Christopher |date=4 January 2010|work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=21 December 2013}} located around 2037 light-years away.{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=R+Muscae&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = R Muscae – Classical Cepheid (delta Cephei type) |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 21 December 2013}} S Muscae is likewise a classical Cepheid, a yellow-white supergiant ranging between spectral types F6Ib and G0Ib and magnitudes 5.89 to 6.49 over a period of 9.66 days.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19678 |title=S Muscae | author=Watson, Christopher |date=4 January 2010|work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=21 December 2013}} A luminous star around 5.9 times as massive as the Sun, it is a binary star with a blue-white main-sequence star companion likely to be of spectral type B3V to B5V with a mass of just over 5 solar masses,{{cite journal|author=Böhm-Vitense, Erika |display-authors=4 |author2=Evans, Nancy Remage |author3=Carpenter, Kenneth |author4=Beck-Winchatz, Bernhard |author5=Robinson, Richard|date=1997|title=The Mass of the Classical Cepheid S Muscae|journal=The Astrophysical Journal|volume=477|issue=2 |pages=916–25|bibcode = 1997ApJ...477..916B|doi=10.1086/303725|doi-access=free}} one of the hottest and brightest companions of a cepheid known. The two stars orbit each other every 505 days.{{cite journal|last=Evans|first=Nancy Remage|date=1990|title=The orbit and colors of the Cepheid S Muscae|journal= Publications of the Astronomical Society of the Pacific |volume=102|pages= 551–57|bibcode=1990PASP..102..551E|doi=10.1086/132668|doi-access=free}}

Theta Muscae is a triple star system thought to be around 7,500 light-years distant.{{cite web|url=http://stars.astro.illinois.edu/sow/thetamus.html |title=Theta Muscae |last=Kaler|first=Jim|author-link= James B. Kaler |work=Stars|publisher=University of Illinois|access-date=21 November 2013}} It consists of a spectroscopic binary system composed of the Wolf–Rayet star (spectral type: WC5 or 6) and an O-type main-sequence star (spectral type: O6 or O7) that orbit each other every 19 days and a blue supergiant (spectral type: O9.5/B0Iab) set about 46 milliarcseconds apart from them. If the system's estimated distance from Earth is accurate, the binary stars are about 0.5 astronomical units (AU) apart and the supergiant about 100 AU apart from them.{{cite journal|author=Sugawara, Y. |author2=Tsuboi, Y. |author3=Maeda, Y.|date=2008|title=Redshifted Emission Lines and Radiative Recombination Continuum from the Wolf–Rayet Binary θ Muscae: Evidence for a Triplet System?|journal=Astronomy & Astrophysics|volume=490|issue=1 |pages=259–64|url=http://www.aanda.org/articles/aa/pdf/2008/40/aa9302-07.pdf|doi=10.1051/0004-6361:20079302|arxiv = 0810.1208 |bibcode = 2008A&A...490..259S |s2cid=118447784 }} All three are highly luminous; combined, they are likely to be over a million times as luminous as the Sun. TU Muscae is a binary star system located around 15,500 light-years away made up of two hot, luminous, blue main-sequence stars of spectral types O7.5V and O9.5V,{{cite web |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=TU+Muscae&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title=TU Muscae – Eclipsing Binary of Beta Lyrae type (semi-detached) |work=SIMBAD Astronomical Database |publisher=Centre de Données astronomiques de Strasbourg |access-date=28 December 2013}} with masses 23 and 15 times that of the Sun. The stars are so close that they are in contact with each other (overcontact binary) and are classed as a Beta Lyrae variable as their light varies from Earth as they eclipse each other.{{cite journal|last=Terrell|first=Dirk|author2=Munari, Ulisse |author3=Zwitter , Tomaˇz |author4= Nelson, Robert H. |date=2003|title=Observational Studies of Early-type Overcontact Binaries: TU Muscae|journal=The Astronomical Journal|volume=126|issue=6|pages=2988–96|arxiv=astro-ph/0309366|bibcode = 2003AJ....126.2988T |doi = 10.1086/379678 |s2cid=6445980}} The system ranges from apparent magnitude 8.17 to 8.75 over around 1.4 days.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19704 |title=TU Muscae |author=Watson, Christopher |date=4 January 2010|work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=28 December 2013}}

Also known as Nova Muscae 1983, GQ Muscae is a binary system consisting of a white dwarf and small star that is about 10% as massive as the Sun. The two orbit each other every 1.4 hours. The white dwarf accumulates material from its companion star via its accretion disc. After a certain amount has accumulated, the star erupts, as it did in 1983, reaching a magnitude of 7.2.{{cite journal|author=Hachisu, Izumi |author2=Kato, Mariko |author3=Cassatella, Angelo |date=2008|title=A Universal Decline Law of Classical Novae. III. GQ Muscae 1983|journal=The Astrophysical Journal|volume=687|issue=2 |pages=1236–52|bibcode=2008ApJ...687.1236H|doi=10.1086/591415|arxiv = 0806.4253 |s2cid=50476380 }} Discovered with a magnitude of 7.1 on 18 January 1983,{{cite book|last=Liller|first=William|title=Cambridge Astronomy Guide|publisher=CUP Archive|location=Cambridge, United Kingdom|date=1990|page=105|isbn=0-521-39915-7|url=https://books.google.com/books?id=yl04AAAAIAAJ&pg=PA105}} it was the first nova from which X-rays were detected.{{cite journal|last=Duerbeck|first=H.W.|date=2009|title=New Stars and Telescopes: Nova Research in the Last Four Centuries|journal=Astronomische Nachrichten|volume=330|issue=6|pages=568–73|url=http://www.physics.usyd.edu.au/~laszlo/kepek/400ev_novai.pdf|doi=10.1002/asna.200911218|bibcode=2009AN....330..568D|url-status=dead|archive-url=https://web.archive.org/web/20150924073139/http://www.physics.usyd.edu.au/~laszlo/kepek/400ev_novai.pdf|archive-date=2015-09-24}} The soft X-ray transient GRS 1124-683 (also known as Nova Muscae 1991) is a binary object consisting of an orange main-sequence star (GU Muscae) of spectral type K3V–K4V and a black hole of around six solar masses.{{cite journal|last=Kreidberg|first=Laura|author2=Bailyn, Charles D. |author3=Farr, Will M. |author4= Kalogera, Vicky |date=2012|title=Mass Measurements of Black Holes in X-ray Transients: is There a Mass Gap? |journal=The Astrophysical Journal|volume=757|issue=36|pages=17|bibcode=2012ApJ...757...36K|doi=10.1088/0004-637x/757/1/36|arxiv = 1205.1805 |s2cid=118452794}} During the 1991 outburst which led to its discovery, radiation was produced through a process of positron annihilation.{{cite journal |date=1992 |author=Sunyaev, R. |display-authors=4 |author2=Churazov, E. |author3=Gilfanov, M. |author4=Dyachkov, A. |author5=Khavenson, N. |author6=Grebenev, S. |author7=Kremnev, R. |author8=Sukhanov, K. |author9=Goldwurm, A. |author10=Ballet, J. |author11=Cordier, B. |author12=Paul, J. |author13=Denis, M. |author14=Vedrenne, G. |author15=Niel, M. |author16=Jourdain, E. |title=X-ray Nova in Musca (GRS 1124+68): Hard X-ray Source with Narrow Annihilation Line |journal=Astrophysical Journal Letters |volume=389 |issue=2 |pages=L75-78 |bibcode=1992ApJ...389L..75S |doi=10.1086/186352 |doi-access=free }} GR Muscae is an X-ray source composed of a neutron star of between 1.2 and 1.8 times the mass of the Sun and a low-mass star likely to be around the mass of the Sun in close orbit.{{cite journal|author=Cornelisse, R. |display-authors=4 |author2=Kotze, M.M. |author3=Casares, J. |author4=Charles, P.A. |author5=Hakala, P.J.|date=2013|title=The Origin of the Tilted Disc in the Low-mass X-ray Binary GR Mus (XB 1254-690)|journal=Monthly Notices of the Royal Astronomical Society|volume=436|issue=1|pages=910–20|arxiv=1309.4972|doi=10.1093/mnras/stt1654|doi-access=free |bibcode = 2013MNRAS.436..910C |s2cid=119242800 }} Finally, SY Muscae is a symbiotic star system composed of a red giant and white dwarf, where although the larger star is transferring mass to the smaller, no periodic eruption occurs nor does an accretion disc form.{{cite journal |title = High resolution spectroscopy of symbiotic stars I. SY Muscae: orbital elements, M giant radius, distance |author = Schmutz, W. |author2 =Schild, H. |author3 =Muerset, U. |author4 =Schmid, H.M. |journal = Astronomy and Astrophysics |volume=288 |pages = 819–28 |date=1994 |bibcode = 1994A&A...288..819S }} The star system varies in magnitude from 10.2 to 12.7 over a period of 624.5 days.{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=19701 |title=SY Muscae |author=Otero, Sebastian Alberto|date=13 March 2013|work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=11 March 2014}} V415 Muscae is a nova that had an outburst in 8 June 2022 with an apparent magnitude of +8.7.{{Cite web |title=ATel #15435: Spectroscopic monitoring of bright Galactic nova ASASSN-22hw |url=https://www.astronomerstelegram.org/?read=15435 |access-date=2022-06-30 |website=ATel}}

File:Coalsack and Dark Doodad Dark Nebulae.jpg can be seen as the large, dark region near the top of the photo. It extends into the northeast of Musca. The vertical dark column in the lower right of the image is the Dark Doodad Nebula.]]

Three star systems have been discovered to have exoplanets. HD 111232 is a yellow main-sequence star around 78% as massive as the Sun around 95 light-years distant. It has a planet (HD 111232 b) around 6.8 times the mass of Jupiter that has an orbital period around 1143 days.{{cite journal | title=The CORALIE Survey for Southern Extra-solar Planets XII. Orbital Solutions for 16 Extra-solar Planets Discovered with CORALIE | display-authors=4 | 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 & Astrophysics | volume=415 | issue=1 | pages=391–402 | date=2004 | arxiv=astro-ph/0310316 | bibcode=2004A&A...415..391M | doi=10.1051/0004-6361:20034250 | s2cid=5233877 }} HD 112410 is a yellow giant of spectral type G8III located around 439 light-years distant.{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD+112410&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = HD 112410 – Red Giant Branch star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 26 December 2013}} With around 1.54 times the mass of the Sun, it is cooling and expanding along the red-giant branch, having left the main sequence after exhausting its core supply of hydrogen fuel. It has a substellar companion calculated to have a mass 9.2 times that of Jupiter and an orbital period of 124.6 days at a distance around 0.57 AU.{{cite journal|author=Jones, M.I. |display-authors=4 |author2=Jenkins, J.S. |author3=Rojo, P. |author4=Melo, C. H. F. |author5=Bluhm, Paz |date=2013|title=Study of the Impact of the Post-MS evolution of the Host Star on the Orbits of Close-in Planets. II. A Giant Planet in a Close-in Orbit around the RGB Star HIP 63242|journal=Astronomy & Astrophysics|volume=556|issue=A78|pages=5|doi=10.1051/0004-6361/201321660|arxiv = 1306.3939 |bibcode = 2013A&A...556A..78J |s2cid=118618692 }} Yet another member of the Lower Centaurus Crux subgroup, HD 100546 is a young, blue-white Herbig Ae/Be star of spectral type B9V that has yet to settle on the main sequence—the closest of these stars to Earth around 320 light-years distant.{{Cite journal | title=The Disk and Environment of the Herbig Be Star HD 100546 | display-authors=4 | last1=Grady | first1=C. A.| last2=Polomski | first2=E. F. | last3=Henning | first3=Th. | last4=Stecklum | first4=B. | last5=Woodgate | first5=B. E. | last6=Telesco | first6=C. M. | last7=Piña | first7=R. K. | last8=Gull | first8=T. R. | last9=Boggess | first9=A. | last10=Bowers | first10=C. W. | last11=Bruhweiler | first11=F. C. | last12=Clampin | first12=M. | last13=Danks | first13=A. C. | last14=Green | first14=R. F. | last15=Heap | first15=S. R. | last16=Hutchings | first16=J. B. | last17=Jenkins | first17=E. B. | last18=Joseph | first18=C. | last19=Kaiser | first19=M. E. | last20=Kimble | first20=R. A. | last21=Kraemer | first21=S. | last22=Lindler | first22=D. | last23=Linsky | first23=J. L. | last24=Maran | first24=S. P. | last25=Moos | first25=H. W. | last26=Plait | first26=P. | last27=Roesler | first27=F. | last28=Timothy | first28=J. G. | last29=Weistrop | first29=D.|date=2001 | journal=The Astronomical Journal | volume=122 | issue=6 | pages=3396–3406 | bibcode=2001AJ....122.3396G | doi=10.1086/324447 | doi-access=free }} It is surrounded by a circumstellar debris disk from a distance of 0.2 to 4 AU, and again from 13 AU out to a few hundred AU, with evidence for a protoplanet forming at a distance around 47 AU.{{cite journal|author=Quanz, Sasch P. |display-authors=4 |author2=Amara, Adam |author3=Meyer, Michael P. |author4=Kenworthy, Matthew P. |author5=Kasper, Markus |author6=Girard, Julien H.|date=2013|title=A Young Protoplanet Candidate Embedded in the Circumstellar Disk of HD 100546|journal= Astrophysical Journal|volume=766|issue=1 |pages=L1–L6|doi=10.1088/2041-8205/766/1/l1|arxiv = 1302.7122 |bibcode = 2013ApJ...766L...1Q |s2cid=56140977 }} A gap exists between 4 and 13 AU, which appears to contain a large planet around 20 times the mass of Jupiter,{{Cite journal | title = Resolving the Disk Rotation of HD 97048 and HD 100546 in the [O I] 6300A Line: Evidence for a Giant Planet Orbiting HD 100546 | last1 = Acke | first1 = B. | last2 = van der Ancker | first2 = M. | journal = Astronomy & Astrophysics | date = 2005 | volume = 449 | issue = 267 | arxiv = astro-ph/0512562|doi = 10.1051/0004-6361:20054330 | bibcode=2006A&A...449..267A | pages = 267| s2cid = 10148216 }} although further examination of the disk profile indicates it might be a more massive object such as a brown dwarf or more than one planet.{{cite journal|author=Mulders, Gijs D. |display-authors=4 |author2=Paardekooper, Sijme-Jan |author3=Pani'c, Olja |author4=Dominik, Carsten |author5=van Boekel, Roy |author6=Ratzka, Thorsten|date=2013|title=Planet or Brown Dwarf? Inferring the Companion Mass in HD 100546 from the Wall Shape using Mid-Infrared Interferometry|journal=Astronomy & Astrophysics|volume=557A|bibcode=2013A&A...557A..68M|arxiv=1306.4264|pages=10|issue=A68|doi = 10.1051/0004-6361/201220930 |s2cid=9014058 }} LP 145-141 is a white dwarf located 15 light-years distant—the fourth-closest to the Solar System.{{cite journal|title= The White Dwarfs Within 20 Parsecs of the Sun: Kinematics and Statistics | author=Sion, Edward M. |display-authors=4 | author2=Holberg, Jay B. | author3=Oswalt, T.D. | author4=McCook, G.P. | author5=Wasatonic, R.| journal= The Astronomical Journal | volume=138 |issue=6 |date=2009| pages=1681–89 [Table 1] | doi=10.1088/0004-6256/138/6/1681| bibcode=2009AJ....138.1681S |arxiv = 0910.1288 | s2cid=119284418 }} It is considered a good candidate to look for Jupiter-like planets, on account if its proximity and mass.{{cite journal|author=Burleigh, Matthew R. |author2=Clarke, F.J. |author3=Hodgkin, S.T. |date=2002|title=Imaging Planets around Nearby White Dwarfs|journal=Monthly Notices of the Royal Astronomical Society|volume=331|issue=4|pages=L41–L45|bibcode=2002MNRAS.331L..41B|doi=10.1046/j.1365-8711.2002.05417.x|doi-access=free |arxiv = astro-ph/0202194 |s2cid=18383063 }}

=Deep-sky objects=

Located on the border with Circinus is the unusual planetary nebula NGC 5189, estimated to be around 1750 light-years away from Earth.{{cite web |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=NGC+5189&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title=NGC 5189 – Planetary Nebula |work=SIMBAD Astronomical Database |publisher=Centre de Données astronomiques de Strasbourg |access-date=29 December 2013}} Its complex structure is due to multiple ejections of material from the ageing central star, which are distorted by the presence of a likely binary companion.{{cite web|url=http://www.nasa.gov/mission_pages/hubble/science/ngc5189.html|title=A Cosmic Holiday Ornament, Hubble-Style|last=Villard|first=Ray |date=18 December 2012|work=Hubble Space Telescope|publisher=NASA|access-date=31 December 2013}} Located 2.4° east of Eta Muscae is the magnitude-12.9 Engraved Hourglass Nebula (MyCn 18),{{cite book |title=1001 Celestial Wonders to See Before You Die: The Best Sky Objects for Star Gazers |first=Michael E. |last=Bakich |publisher=Springer |location=New York, New York |date=2010 |isbn=978-1-4419-1777-5 |page=159 |url=https://books.google.com/books?id=qEhpS7d5ZdAC&pg=PA159}} which lies about 8000 light-years distant from Earth.{{cite journal|author=Sahai, Raghvendra |display-authors=4 |author2=Dayal, Aditya |author3=Watson, Alan M. |author4=Trauger, John T. |author5=Stapelfeldt, Karl R. |author6=Burrows, Christopher J. |author7=Gallagher, John S. III |author8=Scowen, Paul A. |author9=Hester, J. Jeff |author10=Evans, Robin W. |author11=Ballester, Gilda E. |author12=Clarke, John T. |author13=Crisp, David |author14=Griffiths, Richard E. |author15=Hoessel, John G. |author16=Holtzman, Jon A. |author17=Krist, John |author18=Mould, Jeremy R.|date=1999|title=The Etched Hourglass Nebula MYCN 18. I. Hubble Space Telescope Observations |bibcode-access=free |journal=The Astronomical Journal|volume=118|issue=1 |pages=468–76|doi=10.1086/300939|bibcode = 1999AJ....118..468S |doi-access=free }} To Eta's west lies IC 4191, a compact bluish planetary nebula of magnitude 10.6,{{cite book|last=Griffiths|first=Martin|date=2012|title=Planetary Nebulae and How to Observe Them |pages=198–200| isbn=978-1-4614-1782-8 |publisher=Springer |location=New York, New York |url=https://books.google.com/books?id=gsI1S_KVDxoC&q=musca+nebula&pg=PA198}} thought to lie around 10,750 light-years away from Earth.{{cite journal|last=Zhang|first=C.Y.|date=1993|title=On the Distance to Galactic Planetary Nebulae|journal=Astrophysical Journal, Part 1|volume=410|issue=1|pages=239–50|bibcode=1993ApJ...410..239Z|doi=10.1086/172740}} West of Epsilon Muscae is NGC 4071, a large, diffuse planetary nebula of magnitude 12.7 with a magnitude 12 central star, thought to lie around 4000 light-years away from Earth. The Coalsack Nebula is a dark nebula located mainly in neighbouring Crux that intrudes into Musca.{{cite book|last=Darling|first=David J. |title=The Universal Book of Astronomy: from the Andromeda Galaxy to the Zone of Avoidance|publisher=Wiley|location=Hoboken, New Jersey|date=2004|page=351|isbn=0-471-26569-1}} NGC 4463 is an open cluster located on its southwestern border.{{cite book|last=Inglis|first=Mike|title=Astronomy of the Milky Way: Observer's Guide to the Southern Sky|publisher=Springer |location=New York, New York|date=2004|page=83|isbn=1-85233-742-7|url=https://books.google.com/books?id=1r0qvMjSCGAC&pg=SA3-PA12}} Around five light-years across, it is located around 3400 light-years away.

The comparatively old globular cluster NGC 4833 near Delta Muscae was catalogued by Lacaille in 1755. It is 21,200 light-years distant and somewhat obscured by dust clouds near the galactic plane. The globular cluster NGC 4372 near Gamma Muscae is fainter and likewise partially obscured by dust, but spans more arc minutes.{{cite book|last=Consolmagno|first=Guy |title=Turn Left at Orion: Hundreds of Night Sky Objects to See in a Home Telescope – and How to Find Them|publisher=Cambridge University Press|location=Cambridge, United Kingdom|date=2011|page=235 |isbn=978-1-139-50373-0|url=https://books.google.com/books?id=h3712RgWkOYC&pg=PA235}} It is 18,900 light-years away from Earth and 23,000 light-years distant from the centre of the Milky Way. Its extremely low metallicity indicates it is very old—one of the oldest clusters in the Milky Way.{{cite book |title=Deep-Sky Companions: Southern Gems |first=Stephen James |last=O'Meara |publisher=Cambridge University Press|location=Cambridge, United Kingdom |date=2013 |pages=218–21 |isbn=978-1-107-01501-2|url=https://books.google.com/books?id=S5QIEKns33sC&pg=PA220}} Extending south from it is the Dark Doodad Nebula, resembling a dark L-shaped river through a bright field of stars.{{cite book |url=https://books.google.com/books?id=roXyxpcc9MsC&pg=PA95 |title=Nebulae and How to Observe Them |publisher=Springer |location=New York, New York |first=Steven R. |last=Coe |page=95 |date=2007 |isbn=978-1-84628-482-3}} Another dark nebula in the constellation is BHR 71.

Notes

References

{{reflist| refs =

{{cite web| last = Horvatin| first = Shane| title = Obsolete Constellations: Apis| publisher = Michigan State University| location = East Lansing, Michigan| access-date = 14 August 2023| url = https://web.pa.msu.edu/people/horvatin/Astronomy_Facts/obsolete_pages/apis.htm}}

}}

External links

[http://www.allthesky.com/constellations/chamaeleon/ The Deep Photographic Guide to the Constellations: Musca]
[http://astrojan.nhely.hu/musca.htm The clickable Musca]
[http://www.starrynightphotos.com/constellations/musca.htm Starry Night Photography: Musca]

Category:Southern constellations

Category:Constellations listed by Petrus Plancius