S Muscae is a classical (δ) Cepheid

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Musca Musca () 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 in dia ...

about 2,600 light years away. SMusLightCurve

S Muscae is a

yellow supergiant A yellow supergiant (YSG) is a star, generally of spectral type F or G, having a supergiant luminosity class (e.g. Ia or Ib). They are stars that have evolved away from the main sequence, expanding and becoming more luminous. Yellow supergiants ...

ranging between spectral types F6Ib and G0Ib and magnitudes 5.89 to 6.49 over a period of 9.66 days. It is a luminous star around six times as massive as the Sun and 65.1 times the radius of the Sun. It is a

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

with a blue-white

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

star companion likely to be of spectral type B3V to B5V with a mass of just over five solar masses, one of the hottest and brightest companions of a Cepheid known. The two stars orbit each other every 505 days. S Muscae has been found to lie within the faint star cluster ASCC 69.

References

{{DEFAULTSORT:S Muscae Musca Classical Cepheid variables Muscae, S 4645 106111 059551 CD-69 00977 Binary stars