Star · K0
HIP 81691
HIP 81691 is a supergiant star of spectral type K0 in the constellation Ophiuchus, 744.1 light-years from the Sun.
| Constellation | Ophiuchus |
|---|---|
| Distance | 744.1 light-years (228.1 pc) |
| Apparent magnitude | magnitude 6.40 |
| Absolute magnitude | magnitude −0.39 |
| Spectral type | K0 |
| Surface temperature | 4,700 K |
| Luminosity | 197 L☉ |
| Radius | 21.2 R☉ |
| Mass | 4.11 M☉ (estimated) |
| Right ascension (J2000) | 16h 41m 16.7s |
| Declination (J2000) | +1° 14′ 44″ |
| Space velocity (relative to the Sun) | 45.3 km/s |
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 6.40). Visible from the whole Northern Hemisphere and south to latitude 89° S. It stands highest at midnight in May, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around the year 1282. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 13 million years.
The Sun seen from there
From a planet around HIP 81691, the Sun would look like a star of magnitude 11.62, in the direction where our sky has the constellation Eridanus. It would be invisible to the naked eye.
Position, brightness and colour from the HYG / AT-HYG catalogue; temperature, luminosity, radius and mass are approximate values computed from these observations.