Star · F5II
21 Ori
21 Ori is a bright giant star of spectral type F5II in the constellation Orion, 199.7 light-years from the Sun.
| Other names | HIP 24817 |
|---|---|
| Constellation | Orion |
| Distance | 199.7 light-years (61.2 pc) |
| Apparent magnitude | magnitude 5.34 |
| Absolute magnitude | magnitude 1.40 |
| Spectral type | F5II |
| Surface temperature | 6,820 K |
| Luminosity | 23.3 L☉ |
| Radius | 3.46 R☉ |
| Mass | 2.23 M☉ (estimated) |
| Right ascension (J2000) | 5h 19m 11.2s |
| Declination (J2000) | +2° 35′ 45″ |
| Space velocity (relative to the Sun) | 17.9 km/s |
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 5.34). Visible from the whole Northern Hemisphere and south to latitude 87° S. It stands highest at midnight in December, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around the year 1826. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 3.5 million years.
The Sun seen from there
From a planet around 21 Ori, the Sun would look like a star of magnitude 8.77, in the direction where our sky has the constellation Ophiuchus. It would be invisible to the naked eye.
Neighbours
Its nearest neighbours in the catalogue (within 20 light-years):
- HIP 25435 8.34 light-years
- HIP 25082 10.3 light-years
- HIP 24180 12.7 light-years
- 27 Ori 17.5 light-years
- HIP 23701 17.9 light-years
Position, brightness and colour from the HYG / AT-HYG catalogue; temperature, luminosity, radius and mass are approximate values computed from these observations.