Psi Centauri, which is Latinized from ψ Centauri, 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 ...

system 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. It is visible to the naked eye with a baseline apparent visual magnitude of +4.05. The distance to this system is approximately 259

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 based on

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 ...

. The

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

is poorly constrained, but it appears to be slowly drifting away from the Sun at the rate of +2 km/s. PsiCenLightCurve

This is a detached eclipsing binary system with the secondary eclipse being total. The pair are orbiting each other with a period of 38.81 days and an eccentricity of 0.55. The brightness of the system dips by 0.28 and 0.16 magnitude during the two eclipses per orbit. The system displays an infrared excess at a wavelength of 60

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

, indicating the presence of a circumstellar debris disk with a temperature of 120 K, orbiting at a distance of 64 AU. The pair have a combined

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 A0 IV, matching a white-hued A-type subgiant. The two components appear to be at different evolutionary stages. Both have high rotation rates, with

projected rotational velocities 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 bulge ...

over 120 km/s. The primary has 3.6 times the Sun's radius while the secondary is 1.8 times. The primary showed evidence of pulsational behavior with 1.996 and 5.127 cycles per day, which suggests it is a

slowly pulsating B star A slowly pulsating B-type star (SPB), formerly known as a 53 Persei variable, is a type of pulsating variable star. They may also be termed a long-period pulsating B star (LPB). As the name implies, they are main-sequence stars of spectral type B2 ...

. But this remains unconfirmed as of 2017, and the finding may instead be the result of instrumental error.

References

{{DEFAULTSORT:Psi Centauri A-type subgiants Eclipsing binaries Centaurus Centauri, Psi Durchmusterung objects 070090 125473 5367