Tau⁵ Eridani, Latinized from τ⁵ Eridani, is a binary star system in the constellation Eridanus. It is visible to the naked eye with a combined

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 ...

of 4.26. The distance to this system, as estimated using the parallax technique, is around 293 light years. Tau⁵ Eridani is a double-lined spectroscopic binary system. The two stars orbit each other closely with a

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

of 6.2 days and an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.2. On average, the two stars are separated by around 0.183 AU. The primary component 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 B0 V. It is around 157 million years old and is spinning 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 55 km/s. The star has around 3.3 times the mass of the Sun and 3.2 times the Sun's radius. It radiates 188 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 ...

from an outer atmosphere at an effective temperature of 12,514 K. The secondary component has a stellar classification of B9 V. It is slightly smaller, with an estimated size equal to 2.6 times the radius of the Sun. Although τ⁵ Eridani has no bright visual companion stars, the galaxy IC 1953 is less than 10' away. It is one of the brighter members of a loose group of galaxies called the Eridanus Group scattered around the components of τ Eridani.

References

{{DEFAULTSORT:Tau5 Eridani B-type main-sequence stars Eridanus (constellation) Eridani, Tau5 Eridani, 19 022203 016611

1088 Year 1088 ( MLXXXVIII) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar. Events By place Europe * Almoravid forces (supported with fighters from local Andalusian provinces), under Sult ...

Spectroscopic binaries Durchmusterung objects