Star · K1
τ Sgr
τ Sgr is a supergiant star of spectral type K1 in the constellation Sagittarius, 115.2 light-years from the Sun.
| Other names | GJ 9643 · HIP 93864 |
|---|---|
| Constellation | Sagittarius |
| Distance | 115.2 light-years (35.3 pc) |
| Apparent magnitude | magnitude 3.32 |
| Absolute magnitude | magnitude 0.58 |
| Spectral type | K1 |
| Surface temperature | 4,370 K |
| Luminosity | 101 L☉ |
| Radius | 17.5 R☉ |
| Mass | 3.4 M☉ (estimated) |
| Right ascension (J2000) | 19h 06m 56.4s |
| Declination (J2000) | −27° 40′ 14″ |
| Space velocity (relative to the Sun) | 59.4 km/s |
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 3.32). Visible from the whole Southern Hemisphere and north to latitude 62° N. South of latitude 62° S it never sets. It stands highest at midnight in July, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around the year 1911. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 2.0 million years.
The Sun seen from there
From a planet around τ Sgr, the Sun would look like a star of magnitude 7.57, in the direction where our sky has the constellation Gemini. It would be invisible to the naked eye.
Neighbours
Its nearest neighbours in the catalogue (within 20 light-years):
- HIP 92929 9.18 light-years
- HIP 95849 11.9 light-years
- HIP 92798 12.5 light-years
- HIP 96635 15.8 light-years
- CFBDS J193430.36-214221.0 17.7 light-years
- HIP 91700 18.0 light-years
- HIP 97405 18.3 light-years
- HD 169830 18.8 light-years
Position, brightness and colour from the HYG / AT-HYG catalogue; temperature, luminosity, radius and mass are approximate values computed from these observations.