Meissa
Meissa /ˈmaɪsə/, designated Lambda Orionis (λ Orionis, abbreviated Lambda Ori, λ Ori) is a star in the constellation of Orion. It is a multiple star approximately 1,300 ly away with a combined apparent magnitude of 3.33. The main components are an O8 giant star and a B-class main sequence star, separated by about 4″. Despite Meissa being more luminous and only slightly further away than Rigel, it appears 3 magnitudes dimmer at visual wavelengths, with much of its radiation emitted in the ultraviolet due to its high temperature.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| A | |
| Right ascension | 05h 35m 08.27608s |
| Declination | +09° 56′ 02.9913″ |
| Apparent magnitude (V) | 3.7 |
| B | |
| Right ascension | 05h 35m 08.48130s |
| Declination | +09° 56′ 06.0995″ |
| Apparent magnitude (V) | 5.6 |
| Characteristics | |
| A | |
| Spectral type | O8 III((f)) |
| U−B color index | −1.01 |
| B−V color index | −0.21 |
| B | |
| Spectral type | B0 V |
| U−B color index | −0.77 |
| B−V color index | +0.04 |
| Astrometry | |
| Radial velocity (Rv) | +30.10 km/s |
| A | |
| Proper motion (μ) | RA: +2.896 mas/yr Dec.: −3.183 mas/yr |
| Parallax (π) | 2.5936 ± 0.4032 mas |
| Distance | approx. 1,300 ly (approx. 390 pc) |
| Absolute magnitude (MV) | −4.25 |
| B | |
| Proper motion (μ) | RA: +2.216 mas/yr Dec.: −1.986 mas/yr |
| Parallax (π) | 2.4682 ± 0.1543 mas |
| Distance | 1,320 ± 80 ly (410 ± 30 pc) |
| Absolute magnitude (MV) | −1.94 |
| Details | |
| A | |
| Mass | 27.9±3.3 M☉ |
| Radius | 13.4 R☉ |
| Luminosity | 165,000 L☉ |
| Surface gravity (log g) | 3.90 cgs |
| Temperature | 35,000 K |
| Metallicity [Fe/H] | 0.03 dex |
| B | |
| Mass | 10.3±0.7 M☉ |
| Radius | 4.2±0.8 R☉ |
| Luminosity | 6,300 L☉ |
| Surface gravity (log g) | 4.21±0.10 cgs |
| Temperature | 25,400±500 K |
| Age | 1.8 Myr |
| Other designations | |
| A: HD 36861, HR 1879 | |
| B: HD 36862, HR 1880 | |
| Database references | |
| SIMBAD | λ Ori |
| A | |
| B | |
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