Psi4 Aurigae, Latinized from ψ4 Aurigae, is a single,[9] orange-hued star in the northern constellation of Auriga. It is visible to the naked eye with an apparent visual magnitude of +5.02.[2] With an annual parallax shift of 10.08 ± 0.33 mas,[1] it is approximately 324 light-years (99 parsecs) distant from Earth.
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Auriga |
| Right ascension | 06h 43m 04.97107s[1] |
| Declination | +44° 31′ 28.0220″[1] |
| Apparent magnitude (V) | +5.02[2] |
| Characteristics | |
| Spectral type | K5 III[3] |
| U−B color index | +1.83[2] |
| B−V color index | +1.48[2] |
| Astrometry | |
| Radial velocity (Rv) | −77.35±0.23[4] km/s |
| Proper motion (μ) | RA: −45.43[1] mas/yr Dec.: −29.97[1] mas/yr |
| Parallax (π) | 10.08 ± 0.33 mas[1] |
| Distance | 320 ± 10 ly (99 ± 3 pc) |
| Absolute magnitude (MV) | +0.06[5] |
| Details | |
| Radius | 24.9[6] R☉ |
| Luminosity | 155[6] L☉ |
| Surface gravity (log g) | 2.04±0.24[7] cgs |
| Temperature | 4,085±125[6] K |
| Metallicity [Fe/H] | 0.10±0.08[7] dex |
| Rotational velocity (v sin i) | 4.8[4] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a K-type giant star with a stellar classification of K5 III.[3] It has expanded to 25 times the Sun's radius and is radiating 155 times the Sun's luminosity from its photosphere at an effective temperature of about 4,158 K.[6] The atmosphere displays a significant enhancement of silicon.[10]
It was also known to be part of a much bigger constellation named Telescopium Herschelii before it was unrecognized by the International Astronomical Union (IAU).