Nu Sagittarii
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The Bayer designation Nu Sagittarii (ν Sgr / ν Sagittarii) is shared by two star systems, ν¹ Sagittarii and ν² Sagittarii, in the constellation Sagittarius. The two stars are separated by 0.23° on the sky. Nu Sagittarii also has the traditional name Ain al Rami, from the Arabic عين الرامي cain ar-rāmī meaning eye of the archer. Ptolemy called the nebula Facies.
Nu Sagittarii is often cited as one of the earliest identified double stars. In the Almagest, Ptolemy describes the star as "nebulous and double", referring to the double nature of the star, as well as the nearby globular cluster NGC 6717.
[edit] ν¹ Sagittarii
| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation (pronunciation) |
Sagittarius |
| Right ascension | 18h 54m 10.2s |
| Declination | -22° 44' 42" |
| Apparent magnitude (V) | +4.86 |
| Distance | 1850 ± 900 ly (570 ± 270 pc) |
| Spectral type | K2I+B9V: |
| Other designations | |
Nu-1 Sagittarii is a triple star system lying approximately 1850 light years from Earth. The primary component, Nu-1 Sagittarii A is a spectral type K1 bright giant which has an apparent magnitude of +4.86. It is orbited by two magnitude +10.8 companions: Nu-1 Sagittarii B at a distance of 2.5 arcseconds from the primary, and Nu-1 Sagittarii C at a distance of 28.2 arcseconds.
[edit] ν² Sagittarii
| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation (pronunciation) |
Sagittarius |
| Right ascension | 18h 55m 07.1s |
| Declination | -22° 40' 17" |
| Apparent magnitude (V) | +5.00 |
| Distance | 270 ± 21 ly (83 ± 6 pc) |
| Spectral type | K1Ib/II |
| Other designations | |
Nu-2 Sagittarii A is a spectral type K1 supergiant which has an apparent magnitude of +5.00. It is approximately 270 light years from Earth.
[edit] References
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