136 Tauri

136 Tauri is a white-hued binary star system in the zodiac constellation of Taurus. It has a combined apparent visual magnitude of 4.56,^[2] which is bright enough to be faintly visible to the naked eye. Based upon an annual parallax shift of 7.71±0.22 mas as seen from Earth's orbit,^[1] it is located approximately 420 light years from the Sun. The system is moving nearer with a heliocentric radial velocity of −17.2 km/s,^[5] and is expected to make its closest approach in 6.5 million years at a distance of 150 ly (45 pc).^[2]

136 Tauri

Location of 136 Tauri (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Taurus
Right ascension	05h 53m 19.64606s[1]
Declination	+27° 36′ 44.1378″[1]
Apparent magnitude (V)	4.56[2]
Characteristics
Spectral type	A0 V[3] (A0 V + A0 V)[2]
B−V color index	−0.008±0.009[2]
Variable type	suspected[4]
Astrometry
Radial velocity (Rv)	−17.2±4.2[5] km/s
Proper motion (μ)	RA: +3.72[1] mas/yr Dec.: −10.11[1] mas/yr
Parallax (π)	7.71±0.22 mas[1]
Distance	420 ± 10 ly (130 ± 4 pc)
Absolute magnitude (MV)	−1.00[2]
Orbit[6]
Period (P)	5.969 d
Eccentricity (e)	0.00
Periastron epoch (T)	2,420,147.25±10.0 JD
Argument of periastron (ω) (secondary)	0.00°
Semi-amplitude (K1) (primary)	48.9 km/s
Semi-amplitude (K2) (secondary)	71.0 km/s
Details
136 Tau A
Radius	2.1[7] R☉
Luminosity	197.19[8] L☉
Temperature	8,732[8] K
Rotational velocity (v sin i)	10[9] km/s
Other designations
136 Tau, BD+27°899, HD 39357, HIP 27830, HR 2034, SAO 77675[10]
Database references
SIMBAD	data

This is a close, double-lined spectroscopic binary with an orbital period of 5.96 days and an eccentricity of 0.00.^[6] Tidal effects between the pair may have circularized their orbit and slowed their rotation rates – the primary has a projected rotational velocity of 10 km/s.^[9] They have a combined stellar classification of A0 V,^[3] and both are most likely A-type main-sequence stars of the same class.^[2]