20 Eridani, a blue-white giant star in Eridanus
20 Eridani is a blue-white giant star in the constellation Eridanus. At 384 light years away, it shines at an apparent visual magnitude of 5.23.
20 Eridani (HIP 16803)
20 Eridani is a blue-white giant star in the constellation Eridanus. At 384 light years away, it shines at an apparent visual magnitude of 5.23. It is moving through the Galaxy at a speed of 24.8 km/s relative to the Sun.
Sky position: RA 3h 36.3m, Dec -17° 28.0'
Common designations: 20 Eridani, EG Eridani, HR 1100, HD 22470, HIP 16803, Gaia DR3 5108493960822714752
20 Eridani has the spectral type B8/9III. 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 20 Eridani in the sky
20 Eridani lies in Eridanus. With a declination of -17° 28.0', it is visible from the entire Southern Hemisphere and from the Northern Hemisphere up to about latitude 73° 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 20 Eridani
Astrometry and spectroscopy
| Right Ascension (J2000) | 54.07251712° (3h 36.3m) |
| Declination (J2000) | -17.46707564° (-17° 28.0') |
| Galactic Longitude | 207.47245981° |
| Galactic Latitude | -50.85062977° |
| Proper motion RA | 36.03 mas/yr |
| Proper motion Dec | -7.36 mas/yr |
| Parallax | 8.50 ± 0.47 mas |
| Spectral Type | B8/9III |
| Radial Velocity | 14.00 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| U | 4.61 | -0.74 |
| B | 5.10 | -0.25 |
| V | 5.23 | -0.12 |
| J | 5.46 | 0.11 |
| H | 5.56 | 0.21 |
| K | 5.53 | 0.17 |
Colour index B-V: -0.13
Derivations
- Heliocentric distance: 117.63 pc (384 light years) (5.5% margin of error)
- Absolute visual magnitude: -0.12
- Transverse velocity: 20.5 km/s
- Space velocity relative to the Sun: 24.8 km/s
- Galactic position (X, Y, Z): -65.9 pc, -34.3 pc, -91.2 pc
- Galactic velocity (U, V, W): -14.4 km/s, -20.2 km/s, -0.0 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.