V471 Tauri (short V471 Tau) is an eclipsing variable star in the constellation of

Taurus Taurus is Latin for 'bull' and may refer to: * Taurus (astrology), the astrological sign ** Vṛṣabha, in vedic astrology * Taurus (constellation), one of the constellations of the zodiac * Taurus (mythology), one of two Greek mythological ch ...

. The star has a visual magnitude of 9 which makes it impossible to see with the naked eye. It is around 155 light-years away from the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

, in the Hyades star cluster.

Physical properties

The V471 Tauri system has at least two members: a

white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

star of spectral type D2; and a

K-type main sequence star A K-type main-sequence star, also referred to as a K-type dwarf, or orange dwarf, is a main-sequence (hydrogen-burning) star of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars ("r ...

(K2 V), together a post-common envelope binary. There are variations in the timing of the eclipses that were once thought to be due to a third member of the system, proposed to be a

brown dwarf Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big en ...

, but a direct imaging search for this object with

SPHERE A sphere (from Ancient Greek, Greek , ) is a surface (mathematics), surface analogous to the circle, a curve. In solid geometry, a sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...

resulted in a non-detection. The eclipse variations may be caused by the Applegate mechanism, or the third body may be a pair of smaller brown dwarfs, which would be too faint to have been detected. Later studies have found that the timing variations cannot be explained solely by additional components of the system; even if one or more brown dwarfs are present, the Applegate mechanism must also be a factor.

References

{{Stars of Taurus K-type main-sequence stars White dwarfs Eclipsing binaries Taurus (constellation) Tauri, V471 017962 Hyades (star cluster) RS Canum Venaticorum variables