Star · B9III
HIP 21972
HIP 21972 is a giant star of spectral type B9III in the constellation Perseus, 738.5 light-years from the Sun.
| Constellation | Perseus |
|---|---|
| Distance | 738.5 light-years (226.4 pc) |
| Apparent magnitude | magnitude 5.86 |
| Absolute magnitude | magnitude −0.91 |
| Spectral type | B9III |
| Surface temperature | 9,970 K |
| Luminosity | 272 L☉ |
| Radius | 5.53 R☉ |
| Mass | 4.51 M☉ (estimated) |
| Right ascension (J2000) | 4h 43m 21.6s |
| Declination (J2000) | +49° 58′ 26″ |
| Space velocity (relative to the Sun) | 17.3 km/s |
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 5.86). Visible from the whole Northern Hemisphere and south to latitude 40° S. North of latitude 40° N it never sets. It stands highest at midnight in November, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around the year 1288. 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 21972, the Sun would look like a star of magnitude 11.60, in the direction where our sky has the constellation Ara. 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.