Mu Centauri, Latinized from μ Centauri, is a third-magnitude

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

in the southern

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 ...

of Centaurus. With the stars ν and φ Centauri, it marks what has been traditionally portrayed as "''dextro Latere''" (the right side) of the Centau

The apparent visual magnitude of this star is 3.42, making it one of the brighter members of the constellation. The distance to this star can be estimated directly using

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

measurements, which yield a value of roughly 510

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s (155 parsecs) from Earth. MuCenLightCurve

The spectrum of Mu Centauri is considered to be a standard for a B2 Be star with the

stellar classification In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...

of B2V:e. The 'e' suffix is used to mark the presence of emission lines, caused by a circumstellar disk of hot gas that was formed from material ejected from the star. Mu Centauri is a pulsating variable star that has multiple non-radial cycles with a primary period of 0.503 days. Three other pulsation cycles have a similar period, while two have a shorter interval of about 0.28 days. It undergoes outburst events that result in the transfer of additional material to the surrounding disk. During these outbursts, the star can experience transient periodicities. Mu Centauri is classified as a Gamma Cassiopeiae type variable star and its brightness varies from magnitude +2.92 to +3.49. This star is spinning rapidly, with a projected rotational velocity of 194, km s⁻¹ and is completing a full rotation in about 11.615 hours. The equatorial azimuthal velocity is around 85% of the critical velocity where the star would start to break up, resulting a pronounced equatorial bulge that is about 26% wider than the radius at the poles. Because of the

oblate spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters. A spheroid has circ ...

al shape of this star, the polar region is at a higher temperature than the equator—23,000 K versus 17,600 K respectively. Likewise, the gravitational force at the poles is greater than along the equator. The axis of rotation of the star is tilted by an angle of about (19 ± 3)° to the line of sight from the Earth. At an estimated age of nearly 20 million years, this star is around 55–65% of the way through its evolutionary period on the

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 ...

of core hydrogen burning stars. It has around nine times the mass of the Sun and four times the Sun's radius, but emits over 2,000 times as much energy as the Sun. The outer atmosphere has a mean

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of 22,410 K, giving the star a blue-white hue. This star is a

proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...

member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus

OB association In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar velocities in the Milky Way and its satellites as well as t ...

, the nearest such co-moving association of massive stars to the Sun.

References

{{DEFAULTSORT:Mu Centauri B-type main-sequence stars Gamma Cassiopeiae variable stars Upper Centaurus Lupus Centaurus Centauri, Mu Durchmusterung objects 120324 067472 5193