Gamma Sagittarii
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The Bayer designation Gamma Sagittarii (γ Sgr / γ Sagittarii) is shared by two star systems in the constellation Sagittarius, γ1 Sagittarii and γ2 Sagittarii. They are separated by 0.86° on the sky, and can be resolved by the human eye.
[edit] γ¹ Sagittarii
| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation (pronunciation) |
Sagittarius |
| Right ascension | 18h 05m 01.3s |
| Declination | -29° 34' 48" |
| Apparent magnitude (V) | +4.66 (mean) |
| Distance | 2000 ± 1200 ly (600 ± 370 pc) |
| Spectral type | F4-G1Ib |
| Other designations | |
Gamma-1 Sagittarii (γ¹ Sgr / γ¹ Sagittarii) is a cepheid variable star in the constellation Sagittarius. It is often referred to by its variable star designation, W Sagittarii.
This variable star changes in apparent magnitude from +4.3 to +5.1 with a period of 7.59 days. Its change in brightness is accompanied by a change in spectral classification, from G1 to F4. Based on its variablility, W Sagittarii has been estimated to be approximately 1500 light years from Earth.
W Sagittarii also shows evidence of being a close binary star, as well has having two more distant 13th magnitude companions, W Sagittarii B, and C separated by 33 and 48 arcseconds respectively.
[edit] γ² Sagittarii
| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation (pronunciation) |
Sagittarius |
| Right ascension | 18h 05m 48.5s |
| Declination | -30° 25' 27" |
| Apparent magnitude (V) | +2.98 |
| Distance | 96.1 ± 2.5 ly (29.5 ± 0.8 pc) |
| Spectral type | K0III |
| Other designations | |
Gamma-2 Sagittarii (γ² Sgr / γ² Sagittarii) is a star in the constellation Sagittarius. It also has the traditional names Nash, Alnasl, Nasl, or El Nasl, which are derived from the Arabic النصل an-naşl meaning arrowhead.
Alnasl is a spectral type K0 giant, and has an apparent magnitude of +2.98. Alnasl is 96 light years from Earth.
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