V1057 Cygni

V1057 Cygni is a suspected binary star^[8] system in the northern constellation of Cygnus. It is a variable star of the FU Orionis-type, and was the second FU Orionis-type variable to be discovered. The system is located at a distance of approximately 3,000 light years from the Sun,^[3] in the North America Nebula.^[4] It has an apparent visual magnitude of around 12.4.^[4]

V1057 Cygni

A visual band light curve for V1057 Cygni. The main plot shows the long-term variability, and the inset shows the short-term variability. Adapted from Kopatskaya et al. (2002)[1] and Clarke et al. (2005).[2]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Cygnus
Right ascension	20h 58m 53.73367s[3]
Declination	+44° 15′ 28.3847″[3]
Apparent magnitude (V)	12.43±0.03[4]
Characteristics
Spectral type	F7/G3 I/IIe[5]
B−V color index	1.93[6]
Variable type	FU Ori
Astrometry
Proper motion (μ)	RA: −2.793[3] mas/yr Dec.: −3.813[3] mas/yr
Parallax (π)	1.0864±0.0388 mas[3]
Distance	3,000 ± 100 ly (920 ± 30 pc)
Details
Radius	16.2+1.2 −3.2[3] R☉
Luminosity	38.3±2.0[3] L☉
Temperature	3,565+414 −127[3] K
Other designations
V1057 Cyg, LkHα 190, AAVSO 2055+43[7]
Database references
SIMBAD	data

The initial classification of the primary was as a young T Tauri star.^[4] During 1969–1970 it underwent a nova-like outburst, increasing in brightness by five magnitudes and emitting a strong mass outflow. For the next ten years the brightness stayed at a plateau before decreasing rapidly in the mid–1990s, accompanied by a change in its spectrum. As of 2013, it is 1.5 magnitudes brighter than it was before the nova-like event.^[8] The mass of FU Ori objects is estimated to be in the range of 0.3–0.7 M_☉.^[4]

A faint binary companion was discovered in 2016, and designated component B. It is located at a projected separation of 30±5 AU from the primary, with a possible orbital period of ~300 years. The 1970 outburst of the primary may have been caused by torque of its accretion disk by the companion.^[4]