|Right ascension||12.456 h|
|Area||138 sq. deg. (77th)|
|Stars with planets||3|
|Stars brighter than 3.00m||1|
|Stars within 10.00 pc (32.62 ly)||1|
|Brightest star||α Mus (2.69m)|
|Nearest star||Gliese 440
(15.07 ly, 4.62 pc)
|Visible at latitudes between +10° and −90°.
Best visible at 21:00 (9 p.m.) during the month of May.
Musca (Latin: fly) is one of the minor southern constellations. The constellation was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman and it first appeared on a 35-cm diameter celestial globe published in 1597 (or 1598) in Amsterdam by Petrus Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603.
Musca, under its original name Apis – the Bee, was introduced in the late 16th century by Isaac Bautista to fill the previously uncharted area around the southern pole and to provide nourishment for the nearby constellation Chamaeleon (17th-century celestial maps clearly show the chameleon's tongue trying to catch the insect). In 1752 Nicolas Louis de 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 extant constellation depicting an insect.
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. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'Mus'. The official constellation boundaries, as set by 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 11h 19.3m and 13h 51.1m, while the declination coordinates are between −64.64° and −75.68°. As one of the deep southern constellations, it remains below the horizon at latitudes north of the 30th parallel in the Northern Hemisphere, and is circumpolar at latitudes south of the 50th parallel in the Southern Hemisphere.
Lacaille charted and designated 10 stars with the Bayer designations Alpha through 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. 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.
The pattern of the brightest stars resembles that of Ursa Minor. Lying southsoutheast of Acrux in neighbouring Crux, is Alpha Muscae. It is the brightest star in the constellation with an apparent magnitude of 2.7. A blue-white star of spectral type B2IV-V, it is a pulsating star known as a Beta Cephei variable. Beta Muscae is a binary star system composed of two blue-white main sequence stars of spectral types B2V and B3V shining with a combined magnitude of 3.05. Marking the fly's tail is Gamma Muscae, a blue-white star of spectral type B5V and magnitude 3.84. Alpha, Beta and Gamma are all members of the Scorpius–Centaurus Association, a group of not blue-white stars that share a common origin and proper motion across the galaxy.
Lambda Muscae is the third brightest star in the constellation, and is a white star of spectral type A7III.
Delta and Epsilon mark the fly's left wing and right wing respectively. Epsilon Muscae is a red giant of apparent magnitude 4.11 and spectral type M5III. Located near Alpha is R Muscae, a Cepheid variable ranging from apparent magnitude 6.4 to 7.3 over 7.5 days.
The soft X-ray transient 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 6 solar masses. During the 1991 outburst which led to its discovery, radiation was produced through a process of positron annihilation. Musca also contains the unusual planetary nebula NGC 5189, located about 3,000 light years from earth. Its uniquely complex structure resembles a miniature crab nebula. Also within the constellation is the Hourglass Nebula (MyCn 18) at a distance of about 8,000 light years. The comparatively old globular cluster NGC 4833 near Delta Muscae 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.
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- Wagman, Morton (2003). Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others. Blacksburg, VA: The McDonald & Woodward Publishing Company. pp. 213–14. ISBN 978-0-939923-78-6.
- "Alpha Muscae - Variable Star of beta Cephei type". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 11 December 2013.
- Kreidberg, Laura; Bailyn, Charles D.; Farr, Will M.; Kalogera, Vicky (2012). "Mass Measurements of Black Holes in X-ray Transients: is There a Mass Gap?". The Astrophysical Journal 757 (36): 17pp. Bibcode:2012ApJ...757...36K.
- Hamilton, Thomas W. (1968), Useful Star Names, Viewlex
- The Deep Photographic Guide to the Constellations: Musca
- Starry Night Photography: Musca
- Star Tales – Musca
- Musca Constellation at Constellation Guide
Media related to Musca at Wikimedia Commons