22 Eridani, a blue-white giant star in Eridanus
22 Eridani is a blue-white giant star in the constellation Eridanus. At 622 light years away, it shines at an apparent visual magnitude of 5.53.
22 Eridani (HIP 17167)
22 Eridani is a blue-white giant star in the constellation Eridanus. At 622 light years away, it shines at an apparent visual magnitude of 5.53. It is moving through the Galaxy at a speed of 17.9 km/s relative to the Sun.
Sky position: RA 3h 40.6m, Dec -5° 12.6'
Common designations: 22 Eridani, FY Eridani, HR 1121, HD 22920, HIP 17167, Gaia DR3 3247725252713846528
22 Eridani has the spectral type B9IIIpSi4200. B-type stars are hot (about 10,000 to 30,000 K), luminous and blue-white. They are massive, short-lived stars, typically only tens of millions of years old, and are common in young clusters and OB associations. Its luminosity class III marks it as a giant: an evolved star that has left the main sequence and swollen to many times its original size.
How to find 22 Eridani in the sky
22 Eridani lies in Eridanus. With a declination of -5° 12.6', it is visible from the entire Southern Hemisphere and from the Northern Hemisphere up to about latitude 85° N. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around December, which makes the weeks around that month the best time to observe it.
Tabulated data for 22 Eridani
Astrometry and spectroscopy
| Right Ascension (J2000) | 55.15972131° (3h 40.6m) |
| Declination (J2000) | -5.21070993° (-5° 12.6') |
| Galactic Longitude | 192.09913503° |
| Galactic Latitude | -44.18296134° |
| Proper motion RA | 0.49 mas/yr |
| Proper motion Dec | -5.44 mas/yr |
| Parallax | 5.24 ± 0.09 mas |
| Spectral Type | B9IIIpSi4200 |
| Radial Velocity | 17.20 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| U | 4.81 | -1.59 |
| B | 5.38 | -1.02 |
| V | 5.53 | -0.87 |
| J | 5.76 | -0.64 |
| H | 5.79 | -0.61 |
| K | 5.87 | -0.53 |
Colour index B-V: -0.15
Derivations
- Heliocentric distance: 190.83 pc (622 light years) (1.8% margin of error)
- Absolute visual magnitude: -0.87
- Transverse velocity: 4.9 km/s
- Space velocity relative to the Sun: 17.9 km/s
- Galactic position (X, Y, Z): -133.8 pc, -28.7 pc, -133.0 pc
- Galactic velocity (U, V, W): -9.6 km/s, -6.5 km/s, -13.7 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.