Psi Scorpii
White-hued star in the constellation Scorpius
From Wikipedia, the free encyclopedia
Psi Scorpii, which is Latinized from ψ Scorpii, is a binary star in the zodiac constellation of Scorpius. It is white in hue and has an apparent visual magnitude of 4.94,[2] which is bright enough to be faintly visible to the naked eye. Based upon parallax measurements,[1] it is located at a distance of around 162 light years from the Sun. The system is drifting closer to the Sun with a radial velocity of −5 km/s.[4]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius |
| Right ascension | 16h 12m 00.01043s[1] |
| Declination | −10° 03′ 50.8353″[1] |
| Apparent magnitude (V) | 4.94[2] |
| Characteristics | |
| Spectral type | A1 V[3] |
| U−B color index | +0.11[2] |
| B−V color index | +0.09[2] |
| Astrometry | |
| Radial velocity (Rv) | −5.10[4] km/s |
| Proper motion (μ) | RA: −18.000[1] mas/yr Dec.: −36.188[1] mas/yr |
| Parallax (π) | 20.1801±0.2617 mas[1] |
| Distance | 162 ± 2 ly (49.6 ± 0.6 pc) |
| Absolute magnitude (MV) | +1.55[5] |
| Orbit[6] | |
| Period (P) | 10 years |
| Semi-major axis (a) | 6.4 au |
| Details[6] | |
| ψ Sco A | |
| Mass | 1.95 M☉ |
| Radius | 2.1 R☉ |
| Luminosity | 18.6[7] L☉ |
| Surface gravity (log g) | 4.134±0.071[8] cgs |
| Temperature | 8,350 K |
| Rotational velocity (v sin i) | 42.3±0.6[9] km/s |
| Age | 630 Myr |
| ψ Sco B | |
| Mass | 0.64 M☉ |
| Radius | 0.60 R☉ |
| Temperature | 4,200 K |
| Age | 630 Myr |
| Other designations | |
| ψ Sco, 15 Scorpii, BD−09°4324, FK5 3280, GC 21780, HD 145570, HIP 79375, HR 6031, SAO 141022[10] | |
| Database references | |
| SIMBAD | data |
Characteristics
Data collected during the Hipparcos mission suggested it is an astrometric binary.[11] The companion was directly detected in 2025, with the GRAVITY instrument at VLTI. The astrometric data is consistent with an orbital period of 10 years, suggesting a separation of 3.4 astronomical units.[6]
The primary component is an A-type main sequence star with a stellar classification of A1 V;[3] a class of star that is still fusing hydrogen at its core. It has around 1.95 the mass and 2.1 times the radius of the Sun,[6] and is shining with 18.6 times the Sun's luminosity.[7] The effective temperature of the star's outer atmosphere is 8,350 K. Psi Scorpii A is around 630 million years old[6] and is spinning with a projected rotational velocity of 42.3 km/s.[12]
The secondary has around 0.64 times the mass, 0.6 times the radius and a temperature of 4,200 K. It is 6.7 magnitudes fainter than the primary.[6]