Tau⁷ Eridani is a solitary

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

in the constellation Eridanus. 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 ...

of 5.235. Using the parallax method, the distance to this star can be estimated as around 251

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. This is an A-type main sequence star with a

stellar classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...

of A3 Vs, where the 's' indicates it has narrow

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 ident ...

s. It may be a

chemically peculiar 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 ...

Am star An Am star or metallic-line star is a type of chemically peculiar star of spectral type A whose spectrum has strong and often variable absorption lines of metals such as zinc, strontium, zirconium, and barium, and deficiencies of others, such as c ...

, which means it displays unusual abundances of certain elements in its surface layers. Tau⁷ Eridani appears to be a low

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of a ...

variable that displays slight fluctuations in luminosity over a period of 7.17 days. It is slowly rotating 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 18 km/s, and is around 387 million years old.

References

{{DEFAULTSORT:Tau7 Eridani A-type main-sequence stars Eridanus (constellation) Eridani, Tau7 Eridani, 28 023878 017717

1181 Year 1181 ( MCLXXXI) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. Events By place Europe * King Philip II (Augustus) annuls all loans made by Jews to Christians, and takes a p ...

Durchmusterung objects