HD 37756
Binary star system in the constellation Orion
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HD 37756 is a binary star system in the equatorial constellation of Orion, positioned less than a degree to the north of the bright star Alnitak.[10] It has a blue-white hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.95.[1] The system is located at a distance of approximately 900 light years from the Sun based on parallax,[2] and is drifting further away with a radial velocity of +26 km/s.[7] It is a member of the OB1b subgroup of the Orion OB1 association.[11]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion[1] |
| Right ascension | 05h 40m 50.71498s[2] |
| Declination | −01° 07′ 43.6366″[2] |
| Apparent magnitude (V) | 4.95[1] |
| Characteristics | |
| primary | |
| Spectral type | B2IV-V[3] or B3V[4] |
| U−B color index | −0.83[5] |
| B−V color index | −0.21[5] |
| secondary | |
| Spectral type | B1[6] |
| Astrometry | |
| Radial velocity (Rv) | +26.10[7] km/s |
| Proper motion (μ) | RA: −1.50[2] mas/yr Dec.: −0.84[2] mas/yr |
| Parallax (π) | 3.63±0.37 mas[2] |
| Distance | approx. 900 ly (approx. 280 pc) |
| Absolute magnitude (MV) | −2.74[1] |
| Orbit[8] | |
| Period (P) | 27.154925 d |
| Eccentricity (e) | 0.739±0.007 |
| Periastron epoch (T) | 2447886.076±0.065 HJD |
| Argument of periastron (ω) (secondary) | 81.4±2.4° |
| Semi-amplitude (K1) (primary) | 84.7±1.1 km/s |
| Details | |
| A | |
| Mass | 13.0[6] M☉ |
| B | |
| Mass | 8.3[6] M☉ |
| Other designations | |
| NSV 2556, BD−01°1004, GC 7091, HD 37756, HIP 26736, HR 1952, SAO 132445[9] | |
| Database references | |
| SIMBAD | data |
The binary nature of this system was identified by E. B. Frost in 1906.[12] It is a double-lined spectroscopic binary with an orbital period of 27.15 days and a high eccentricity of 0.74.[8] The spectrum matches a massive B-type main-sequence star with a stellar classification of B3V.[4] The secondary is luminous enough to interfere with measurements of the primary spectrum.[12] It is a suspected Beta Cephei variable with a period of 0.37968 days and an amplitude of 0.03 magnitude in the B band of the UBV photometric system.[13] The system is a candidate eclipsing binary with a minimum dip of 0.04 in visual magnitude during each orbit.[14]