Pi1 Orionis
Star in the constellation Orion
From Wikipedia, the free encyclopedia
Pi1 Orionis (π1 Ori, π1 Orionis) is a star in the equatorial constellation of Orion. It is faintly visible to the naked eye with an apparent visual magnitude of 4.74.[2] Based upon an annual parallax shift of 28.04 mas,[1] it is located about 116 light-years from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Orion |
| Right ascension | 04h 54m 53.72877s[1] |
| Declination | +10° 09′ 02.9952″[1] |
| Apparent magnitude (V) | 4.74[2] |
| Characteristics | |
| Spectral type | A3 Va[3] |
| U−B color index | +0.09[2] |
| B−V color index | +0.08[2] |
| Astrometry | |
| Proper motion (μ) | RA: +41.49[1] mas/yr Dec.: −128.73[1] mas/yr |
| Parallax (π) | 28.04±0.25 mas[1] |
| Distance | 116 ± 1 ly (35.7 ± 0.3 pc) |
| Absolute magnitude (MV) | 1.71±0.09[4] |
| Details[4] | |
| Mass | 1.90+0.08 −0.09 M☉ |
| Radius | 1.73±0.13 R☉ |
| Luminosity | 16.91+1.42 −1.29 L☉ |
| Surface gravity (log g) | 4.22+0.04 −0.05 cgs |
| Temperature | 8,900±131 K |
| Metallicity [Fe/H] | −0.12+0.14 −0.16 dex |
| Rotational velocity (v sin i) | 120[5] km/s |
| Age | 100[6] Myr |
| Other designations | |
| π1 Ori, 7 Orionis, BD+09°683, HD 31295, HIP 22845, HR 1570, SAO 94201[7] | |
| Database references | |
| SIMBAD | data |
This is an A-type main-sequence star with a stellar classification of A3 Va.[3] It is a Lambda Boötis star,[8] which means the spectrum shows lower-than-expected abundances for heavier elements.[9] Pi1 Orionis is a relatively young star, just 100 million years old,[6] and is spinning fairly rapidly with a projected rotational velocity of 120 km/s.[5] It has nearly double the mass of the Sun and 173% of the Sun's radius. The star radiates 16.9 times the solar luminosity from its outer atmosphere at an effective temperature of 8,900 K.[4]
An infrared excess indicates there is a debris disk with a temperature of 80 K orbiting 49 AU from the star. The dust has a combined mass 2.2% that of the Earth.[6]