Theta1 Orionis D
Theta1 Orionis D (θ1 Orionis D) is a member of the Trapezium open cluster that lies within the Orion Nebula. It is a B class blue main sequence star with several faint companions.
Theta1 Orionis D and companions in the Trapezium cluster | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 35m 17.24645s |
| Declination | −05° 23′ 16.5707″ |
| Apparent magnitude (V) | 6.70 |
| Characteristics | |
| Spectral type | B1.5 Vp |
| U−B color index | −0.71 |
| B−V color index | +0.09 |
| Astrometry | |
| Radial velocity (Rv) | +32.4 km/s |
| Proper motion (μ) | RA: +1.822 mas/yr Dec.: _0.393 mas/yr |
| Parallax (π) | 2.2820 ± 0.0207 mas |
| Distance | 1,430 ± 10 ly (438 ± 4 pc) |
| Absolute magnitude (MV) | −3.3 |
| Details | |
| Mass | 18±6 M☉ |
| Radius | 5.6±0.8 R☉ |
| Luminosity | 29,500 L☉ |
| Surface gravity (log g) | 4.2±0.1 cgs |
| Temperature | 32,000±1,000 K |
| Rotational velocity (v sin i) | 49.0±0.9 km/s |
| Age | 2.5±0.5 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
θ1 Orionis consists of multiple components, primarily the four stars of the Trapezium cluster (A, B, C, and D) all within one arc-minute of each other. θ2 Orionis is a more distant grouping of three main stars plus several fainter companions, 1-2 arc-minutes from θ1.
θ1 D itself has a faint optical companion 1.4" away and a spectroscopic companion in a 40-day orbit. Infrared Optical Telescope Array observations suggest another companion at 18.6 mas.
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