Star · A2
21 Com
21 Com is a main-sequence star of spectral type A2 in the constellation Coma Berenices, 270.0 light-years from the Sun.
| Other names | HIP 61071 |
|---|---|
| Constellation | Coma Berenices |
| Distance | 270.0 light-years (82.8 pc) |
| Apparent magnitude | magnitude 5.47 |
| Absolute magnitude | magnitude 0.88 |
| Spectral type | A2 |
| Surface temperature | 9,480 K |
| Luminosity | 48.4 L☉ |
| Radius | 2.58 R☉ |
| Mass | 2.75 M☉ (estimated) |
| Right ascension (J2000) | 12h 31m 00.6s |
| Declination (J2000) | +24° 34′ 02″ |
| Space velocity (relative to the Sun) | 7.1 km/s |
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 5.47). Visible from the whole Northern Hemisphere and south to latitude 65° S. North of latitude 65° N it never sets. It stands highest at midnight in March, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around the year 1756. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 4.8 million years.
The Sun seen from there
From a planet around 21 Com, the Sun would look like a star of magnitude 9.42, in the direction where our sky has the constellation Cetus. It would be invisible to the naked eye.
Neighbours
Its nearest neighbours in the catalogue (within 20 light-years):
Position, brightness and colour from the HYG / AT-HYG catalogue; temperature, luminosity, radius and mass are approximate values computed from these observations.