Mu² Octantis (μ² Oct) 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 of two

G-type main-sequence star A G-type main-sequence star (Spectral type: G-V), also often, and imprecisely called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temp ...

s. It shares the designation μ with μ¹ Octantis, from which it is separated by 50 arcminutes. Mu² Octantis has a 29% higher mass than the sun, and is slightly hotter. Its radius is 73% more than the Sun's and it is nearly four times as luminous. This star is a member of a wider binary star system. The two components are gravitationally bound and separated at in our sky, corresponding to 740

astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits t ...

s (AU). The semimajor axis of the stars' orbit is 932 AU. The companion star is HD 196068, another G-type

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 Hert ...

star with an

apparent 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 li ...

of 7.18.

Planetary system

From 1998 to 2012, the system was observed using the

CORALIE Coralie is a French feminine name meaning "coral", derived from the Latin word ''coralium''.Also spelt ''corallum'', ''corallium'' or ''curalium'', cf.br>Whitaker's Words/ref> It was the eighth most popular name for baby girls in Quebec in 2007. N ...

instrument, at the

ESO The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental research organisation made up of 16 member states for ground-based ast ...

La Silla Observatory La Silla Observatory is an astronomy, astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory (ESO). Several other telescopes are located at the site and are partly maintained by ESO. The obse ...

. In November 2012, a long-period, wide-orbiting

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

was deduced by

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 ...

around HD 196067. The planet has been pulled to an eccentric orbit by the B star HD 196068. The planet's true mass, as measured by

astrometry Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. His ...

, is , placing it right on the boundary between planets and

brown dwarf Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...

References

{{DEFAULTSORT:Mu2 Octantis Planetary systems with one confirmed planet Binary stars Octans Durchmusterung objects 7864 196067 102125 Octantis, Mu G-type main-sequence stars J20414409-7521029