Star · O9I
τ CMa
τ CMa is a supergiant star of spectral type O9I in the constellation Canis Major, 5,658 light-years from the Sun.
| Other names | HIP 35415 |
|---|---|
| Constellation | Canis Major |
| Distance | 5,658 light-years (1,735 pc) |
| Apparent magnitude | magnitude 4.37 |
| Absolute magnitude | magnitude −6.83 |
| Spectral type | O9I |
| Surface temperature | 12,140 K |
| Luminosity | 89,800 L☉ |
| Radius | 67.7 R☉ |
| Mass | 2.81 M☉ (estimated) |
| Right ascension (J2000) | 7h 18m 42.5s |
| Declination (J2000) | −24° 57′ 16″ |
| Space velocity (relative to the Sun) | 51.8 km/s |
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 4.37). Visible from the whole Southern Hemisphere and north to latitude 65° N. South of latitude 65° S 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 5,658 years ago. At that time the first farming villages were being founded; there was no writing yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 100 million years.
The Sun seen from there
From a planet around τ CMa, the Sun would look like a star of magnitude 16.03, in the direction where our sky has the constellation Vulpecula. 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.