ε Fornacis (Latinised as Epsilon Fornacis) is the

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

for a high

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 ...

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 ...

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 Fornax. It is faintly visible to the naked eye with an apparent visual magnitude of 5.89. Based upon an annual parallax shift of 31.06

mas Mas, Más or MAS may refer to: Film and TV * Más y Menos, fictional superhero characters, from the Teen Titans animated television series * Más (Breaking Bad), "Más" (''Breaking Bad''), a season three episode of ''Breaking Bad'' Songs * Más ( ...

, the system is located roughly 105

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 from the Sun. At that distance, its visual magnitude is reduced by an interstellar absorption factor of 0.09 due to dust. This is an

astrometric binary 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 ...

star system. The best fit to the radial velocity data yields an orbital period of roughly 13,770 days (37.7 years) with an eccentricity of around 0.28. The semimajor axis of their computed orbit is about 13 au, or 13 times the distance of the Earth from the Sun. The primary, component A, is an evolved K-type subgiant star with a

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 , where the suffix notation indicates the

absorption line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...

s of iron and the carbon-hydrogen bond are abnormally weak. However, classifications earlier than Gray et al. (2006) consistently showed it as type G5 IV, matching the subgiant categorization. The primary has an estimated 91% of the Sun's mass, but has expanded to 253% times the Sun's radius. It has a quiet ( inactive)

chromosphere A chromosphere ("sphere of color") is the second layer of a star's atmosphere, located above the photosphere and below the solar transition region and corona. The term usually refers to the Sun's chromosphere, but not exclusively. In the Su ...

and is most likely an old star with an age over 12 billion years. The star is spinning slowly 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 bulge ...

of 1.1 km/s. Since leaving 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 ...

, it has increased in luminosity to 4.5 times that of the Sun, which is being radiated from its outer atmosphere at an

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 5,068 K. Based upon its estimated orbit, the secondary, component B, has at least times of the Sun's mass.

References

{{DEFAULTSORT:Epsilon Fornacis K-type subgiants Fornax Fornacis, Epsilon CD-32 1430 023227 14086

1134 . Year 1134 ( MCXXXIV) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. Events By place Asia * Count Hugh II (du Puiset), in alliance with the Egyptian city of Ashkelon, revolts against ...

Astrometric binaries