Centaurus
Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. ...
. It is visible to the naked eye with an
apparent visual magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...
position angle
In astronomy, position angle (usually abbreviated PA) is the convention for measuring angles on the sky. The International Astronomical Union defines it as the angle measured relative to the north celestial pole (NCP), turning positive into the ...
of was detected in 2010 using interferometry, but its association with Sigma Centauri remains undetermined as of 2013. The distance to Sigma Centauri, based upon an annual parallax shift of 7.92 mas, is around 412 light years.
This is a
B-type main sequence star
A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars ...
with a stellar classification of B3 V. It is a helium-rich star, the most massive type of
chemically peculiar star
In astrophysics, chemically peculiar stars (CP stars) are stars with distinctly unusual metal abundances, at least in their surface layers.
Classification
Chemically peculiar stars are common among hot main-sequence (hydrogen-burning) stars. Thes ...
. Sigma Centauri has around 6.8 times the mass of the Sun and 4.5 times the Sun's radius. It has a relatively high rate of spin with a
projected rotational velocity
Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface.
The rotation of a star produces an equatorial bulg ...
of 169 km/s, and is around 25 million years old. The star radiates 1,101 times the
solar luminosity
The solar luminosity (), is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun.
One nominal ...