V773 Tauri

V773 Tauri is a young, multiple star system in the central region^[6] of Taurus, an equatorial constellation. This is a T Tauri-type variable star that ranges in apparent visual magnitude from 10.59 down to 10.95,^[4] which is too faint to be viewed with the naked eye. Based on various estimates, the system is located at a distance of approximately 433 light years from the Sun. It lies near the dark cloud Lynds 1495.^[6]

Aa

Period = 51.1 d

Ab

Period = 26.5 yr

B(ab)

Period = 624 yr

C

Hierarchy of orbits

V773 Tauri

Light curves for V773 Tauri. The upper panel shows the variability as seen by TESS.[1] The lower panel, adapted from Kenworthy et al.,[2] shows the eclipse seen in 2010.
Observation data Epoch J2000      Equinox J2000
Constellation	Taurus
Right ascension	04h 14m 12.926s[3]
Declination	28° 12′ 12.36″[3]
Apparent magnitude (V)	10.59 to 10.95[4]
Characteristics
Spectral type	K3Ve (Li)[5]
Variable type	Orion variable + BY Dra[4]
Astrometry
Proper motion (μ)	RA: 6.540 mas/yr[3] Dec.: −27.792 mas/yr[3]
Parallax (π)	8.3261±0.1313 mas
Distance	433.1 ± 7.5 ly (132.8±2.3 pc)[6]
Orbit[2]
Primary	V773 Tau AB
Companion	V773 Tau C
Period (P)	624+83 −52 yr
Semi-major axis (a)	1,013+93 −74 mas
Eccentricity (e)	0.40+0.04 −0.05
Inclination (i)	97.3±0.6°
Longitude of the node (Ω)	104.6±1.3°
Periastron epoch (T)	1,740+26 −40
Argument of periastron (ω) (secondary)	107.8±4.5°
Orbit[2]
Primary	V773 Tau A
Companion	V773 Tau B
Period (P)	26.50±0.07 yr
Semi-major axis (a)	117.7±0.86 mas
Eccentricity (e)	0.104±0.009
Inclination (i)	69.25±0.40°
Longitude of the node (Ω)	290.54±0.40°
Periastron epoch (T)	2,010.11±0.12
Argument of periastron (ω) (secondary)	266.0±1.5°
Semi-amplitude (K1) (primary)	6.50±0.50[7] km/s
Orbit[6]
Primary	V773 Tau Aa
Companion	V773 Tau Ab
Period (P)	51.1033±0.0018 d
Semi-major axis (a)	2.809±0.033 mas
Eccentricity (e)	0.2713±0.0066
Inclination (i)	68.5±1.6°
Longitude of the node (Ω)	62.4±1.1°
Periastron epoch (T)	53,059.75±0.28 MJD
Argument of periastron (ω) (secondary)	5.6±2.2°
Semi-amplitude (K1) (primary)	35.72±0.46 km/s
Semi-amplitude (K2) (secondary)	42.9±1.3 km/s
Details
Aa
Mass	1.55±0.11[6] M☉
Radius	2.22[8] R☉
Luminosity	2.56[8] L☉
Surface gravity (log g)	3.93[8] cgs
Temperature	4,900[8] K
Age	3±1[2] Myr
Ab
Mass	1.293±0.068[6] M☉
Radius	1.74[8] R☉
Luminosity	1.37[8] L☉
Surface gravity (log g)	4.08[8] cgs
Temperature	4,740[8] K
Other designations
V773 Tau, HD 283447, HIP 19762, WDS J04142+2813A[9]
Database references
SIMBAD	data

This system was identified as a T Tauri star by A. E. Rydgren and associates in 1974.^[10] Radio emission was detected from this source in 1983.^[11] In 1993, it was discovered to be a double star with an angular separation of about 150 mas: the two components are designated A and B. Component A was found to be a double-lined spectroscopic binary with an orbital period of 51 days. In 2003, a third member of this group was located, component C,^[6] at a separation of 256 mas from component A.

Orbital solutions for the A–B pair provide an unexpectedly high dynamic mass of 2.69±0.67 M_☉ for component B, suggesting it too may be a binary system.^[7] A single star with that much mass would have 17 times the luminosity of the Sun, which is inconsistent with the observed optical luminosity. Photometry of component B suggests it is experiencing extinction from dust along the line of sight. The component is variable in the K band, which is consistent with clumps or clouds of dust in orbit.^[2]

In 2010, an extended eclipse was observed in the V773 Tauri system. This was interpreted as a circumbinary disk of component B passing in front of component A. The eclipse obscured 70% of the emission from component A and lasted 150 days.^[2]