HD 37017

HD 37017 is a binary star system in the equatorial constellation of Orion. It has the variable star designation V1046 Orionis; HD 37017 is the identifier from the Henry Draper Catalogue. The system is a challenge to view with the naked eye, being close to the lower limit of visibility with a combined apparent visual magnitude of 6.55.^[3] It is located at a distance of approximately 1,230 light years based on parallax,^[9] and is drifting further away with a radial velocity of +32 km/s.^[8] The system is part of star cluster NGC 1981.^[13]

HD 37017

A light curve for V1046 Orionis, plotted from TESS data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Orion
Right ascension	05h 35m 21.86770s[2]
Declination	−04° 29′ 39.0409″[2]
Apparent magnitude (V)	6.553[3]
Characteristics
Evolutionary stage	B2/3V[4] (B1.5 Vp He strong[5])
U−B color index	−0.79[6]
B−V color index	−0.14[6]
Variable type	SX Ari[7]
Astrometry
Radial velocity (Rv)	+32±2[8] km/s
Proper motion (μ)	RA: 1.88±0.09[9] mas/yr Dec.: 1.20±0.14[9] mas/yr
Parallax (π)	2.643±0.075 mas[9]
Distance	1,230 ± 40 ly (380 ± 10 pc)
Orbit[10]
Period (P)	18.6556±0.0017 d
Semi-major axis (a)	≥12.61±1.09 R☉
Eccentricity (e)	0.31±0.05
Periastron epoch (T)	2,435,461.602±0.168 JD
Argument of periastron (ω) (secondary)	133±5°
Semi-amplitude (K1) (primary)	36.0±2.5 km/s
Details
A
Mass	8.50±0.53[3] M☉
Luminosity	3,754[3] L☉
Temperature	23,700[3] K
Rotation	0.901 d[11]
Rotational velocity (v sin i)	165[5] km/s
B
Mass	4.5[10] M☉
Other designations
V1046 Orionis, BD−04°1183, HD 37017, HIP 26233, HR 1890, SAO 132317[12]
Database references
SIMBAD	data

The binary nature of this system was suggested by A. Blaauw and T. S. van Albada in 1963.^[10] It is a double-lined^[11] spectroscopic binary with an orbital period of 18.6556 days and an eccentricity of 0.31.^[14] The eccentricity is considered unusually large for such a close system.^[11] It forms a suspected eclipsing binary that ranges in brightness from 6.54 down to 6.58.^[7]

The primary is a helium-strong, magnetic chemically peculiar star^[15] with a stellar classification of B1.5 Vp.^[5] It has a magnetic field strength of 7,700 G,^[16] and the helium concentrations are located at the magnetic poles.^[17] V1046 Orionis was found to be a variable star by L. A. Balona in 1997,^[11] and is now classified as an SX Arietis variable.^[7] The star undergoes periodic changes in visual brightness, magnetic field strength, and spectral characteristics with a cycle time of 0.901175 days – the star's presumed rotation period.^[11] Radio emission has been detected that varies with the rotation period.^[17]

The secondary component has an estimated 4.5 times the mass of the Sun. The class has been estimated as type B6III-IV.^[11]