V471 Tauri

V471 Tauri (short V471 Tau) is an eclipsing variable star in the constellation of Taurus. 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, in the Hyades star cluster.^[6]

V471 Tauri

A light curve for V471 Tauri, plotted from TESS data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Taurus
Right ascension	03h 50m 24.9667s[2]
Declination	17° 14′ 47.431″[2]
Apparent magnitude (V)	9.40 - 9.71[3]
Characteristics
Evolutionary stage	K2V + D2[4]
Variable type	Algol + RS CVn[3]
Astrometry
Radial velocity (Rv)	37.4±0.5[5] km/s
Proper motion (μ)	RA: 127.278[2] mas/yr Dec.: −22.321[2] mas/yr
Parallax (π)	21.0129±0.0158 mas[2]
Distance	155.2 ± 0.1 ly (47.59 ± 0.04 pc)
Orbit[6]
Period (P)	0.52118 days
Semi-major axis (a)	0.01496 AU
Eccentricity (e)	0 (assumed)
Inclination (i)	80.8°
Details
White dwarf
Mass	0.792[6] M☉
Radius	0.01134[6] R☉
Luminosity	0.145[7] L☉
Surface gravity (log g)	8.227[6] cgs
Temperature	34,500[7] K
K star
Mass	0.852[6] M☉
Radius	0.816[6] R☉
Luminosity	0.41[8] L☉
Surface gravity (log g)	4.49[9] cgs
Temperature	5,066[9] K
Metallicity [Fe/H]	+0.12[8] dex
Rotation	0.5211 days[8]
Rotational velocity (v sin i)	89.30[9] km/s
Age	625[9] Myr
Other designations
471 Tau, BD+16°516, HIP 17962
Database references
SIMBAD	data

In 1970, Burt Nelson and Arthur Young announced that the star is a variable star.^[10] It was given its variable star designation in 1972.

Physical properties

The V471 Tauri system has at least two members: a white dwarf star of spectral type D2; and a K-type main sequence star (K2 V), together a post-common envelope binary.^[6][11] 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, but a direct imaging search for this object with SPHERE resulted in a non-detection.^[12] The eclipse variations may be caused by the Applegate mechanism,^[13] or the third body may be a pair of smaller brown dwarfs, which would be too faint to have been detected.^[7] 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.^[14]