Star · K5III
81 Gem
81 Gem is a giant star of spectral type K5III in the constellation Gemini, 310.4 light-years from the Sun.
| Other names | HIP 37908 |
|---|---|
| Constellation | Gemini |
| Distance | 310.4 light-years (95.2 pc) |
| Apparent magnitude | magnitude 4.89 |
| Absolute magnitude | magnitude −0.00 |
| Spectral type | K5III |
| Surface temperature | 3,910 K |
| Luminosity | 272 L☉ |
| Radius | 36 R☉ |
| Mass | 4.51 M☉ (estimated) |
| Right ascension (J2000) | 7h 46m 07.4s |
| Declination (J2000) | +18° 30′ 36″ |
| Space velocity (relative to the Sun) | 93.2 km/s |
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 4.89). Visible from the whole Northern Hemisphere and south to latitude 71° S. North of latitude 71° N it never sets. It stands highest at midnight in January, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around the year 1716. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 5.5 million years.
The Sun seen from there
From a planet around 81 Gem, the Sun would look like a star of magnitude 9.72, in the direction where our sky has the constellation Sagittarius. It would be invisible to the naked eye.
Neighbours
Its nearest neighbours in the catalogue (within 20 light-years):
- SDSS J074912.70+200559.0 13.3 light-years
- HIP 38890 14.9 light-years
Position, brightness and colour from the HYG / AT-HYG catalogue; temperature, luminosity, radius and mass are approximate values computed from these observations.