Gamma Sagittarii

From Freepedia

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.

γ¹ Sagittarii

γ¹ Sagittarii

Epoch J2000.0
Constellation	Sagittarius
Right ascension	18h 05m 01.3s
Declination	-29° 34' 48"
Distance	2000 ± 1200 ly (600 ± 370 pc)
Spectral type	F4-G1Ib
Apparent magnitude	+4.66 (mean)
Other designations
W Sagittarii, HR 6742, HD 164975, SAO 186237, HIP 88567, ADS 11029, CCDM 18050-2935

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.

γ² Sagittarii

γ² Sagittarii

Epoch J2000.0
Constellation	Sagittarius
Right ascension	18h 05m 48.5s
Declination	-30° 25' 27"
Distance	96.1 ± 2.5 ly (29.5 ± 0.8 pc)
Spectral type	K0III
Apparent magnitude	+2.98
Other designations
Alnasl, 10 Sagittarii, HR 6746, HD 165135, SAO 209696, HIP 88635

Gamma-2 Sagittarii (γ² Sgr / γ² Sagittarii) is a star in the constellation Sagittarius. It also has the traditional names 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 a apparent magnitude of +2.98. Alnasl is 96 light years from Earth.