Pi4 Orionis
Binary star system in the constellation Orion
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Pi4 Orionis (π4 Ori, π4 Orionis) is a binary star system in the western part of the Orion constellation. It is visible to the naked eye with an apparent visual magnitude of 3.7.[2] Based upon an annual parallax shift of 3.1 mass,[1] it is located roughly 1,050 light-years from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Orion |
| Right ascension | 04h 51m 12.36472s[1] |
| Declination | +05° 36′ 18.3723″[1] |
| Apparent magnitude (V) | 3.685[2] |
| Characteristics | |
| Spectral type | B2 III[3] |
| U−B color index | −0.797[2] |
| B−V color index | −0.180[2] |
| Astrometry | |
| Radial velocity (Rv) | 23.3[4] km/s |
| Proper motion (μ) | RA: −2.21[1] mas/yr Dec.: +0.85[1] mas/yr |
| Parallax (π) | 3.10±0.18 mas[1] |
| Distance | 1,050 ± 60 ly (320 ± 20 pc) |
| Orbit[5] | |
| Period (P) | 9.5191 d |
| Eccentricity (e) | 0.03 |
| Periastron epoch (T) | 2,418,275.65±10.0 |
| Argument of periastron (ω) (secondary) | 165° |
| Semi-amplitude (K1) (primary) | 25.8 km/s |
| Details | |
| π4 Ori A | |
| Mass | 10.95±0.97[6] M☉ |
| Radius | 9.1[7] R☉ |
| Luminosity | 19,726[6] L☉ |
| Surface gravity (log g) | 3.59[8] cgs |
| Temperature | 21,874±126[7] K |
| Metallicity [Fe/H] | −0.31[8] dex |
| Rotational velocity (v sin i) | 38[9] km/s |
| Age | 15.4±1.0[10] Myr |
| Other designations | |
| π4 Ori, 3 Orionis, BD+05°745, FK5 179, HD 30836, HIP 22549, HR 1552, SAO 112142[11] | |
| Database references | |
| SIMBAD | data |
This is a spectroscopic binary star system with an orbital period of 9.5 days and an eccentricity of 0.03.[5] The primary component is a B-type star with a stellar classification of B2 III.[3] The stellar spectrum of π4 Ori A shows a strong depletion of the element boron.[12] It has nearly 11[6] times the mass of the Sun and nine times the Sun's radius.[7] The star is 15.4[10] million years old and has a projected rotational velocity of 38 km/s.[9] It shines with 19,726[6] times the solar luminosity from its outer atmosphere at an effective temperature of 21,874 K.[7]