Star · M2III
η Sgr
η Sgr is a giant star of spectral type M2III in the constellation Sagittarius, 136.5 light-years from the Sun.
| Other names | HIP 89642 |
|---|---|
| Constellation | Sagittarius |
| Distance | 136.5 light-years (41.9 pc) |
| Apparent magnitude | magnitude 3.10 |
| Absolute magnitude | magnitude −0.01 |
| Spectral type | M2III |
| Surface temperature | 3,670 K |
| Luminosity | 375 L☉ |
| Radius | 47.8 R☉ |
| Mass | 4.94 M☉ (estimated) |
| Right ascension (J2000) | 18h 17m 37.6s |
| Declination (J2000) | −36° 45′ 42″ |
| Space velocity (relative to the Sun) | 42.1 km/s |
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 3.10). Visible from the whole Southern Hemisphere and north to latitude 53° N. South of latitude 53° S it never sets. It stands highest at midnight in June, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around the year 1889. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 2.4 million years.
The Sun seen from there
From a planet around η Sgr, the Sun would look like a star of magnitude 7.94, in the direction where our sky has the constellation Auriga. It would be invisible to the naked eye.
Neighbours
Its nearest neighbours in the catalogue (within 20 light-years):
- Kaus Australis 9.48 light-years
- HIP 90706 9.92 light-years
- Fuyue 13.8 light-years
- HIP 88726 18.4 light-years
- HD 166724 18.5 light-years
- HIP 90936 18.8 light-years
- HIP 86419 18.9 light-years
- HIP 88553 19.7 light-years
Position, brightness and colour from the HYG / AT-HYG catalogue; temperature, luminosity, radius and mass are approximate values computed from these observations.