Epsilon Sagittae

Epsilon Sagittae (ε Sagittae) is a solitary,^[8] yellow-hued star in the northern constellation of Sagitta. With an apparent visual magnitude of +5.64 to +5.67,^[2] it is faintly visible to the naked eye on a dark night. It is a variable star with a small amplitude of 0.03 magnitudes. Based upon an annual parallax shift of 5.60 mas as seen from Earth,^[9] it is located roughly 580 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.1 due to interstellar dust.^[4]

Epsilon Sagittae

Location of ε Sagittae (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Sagitta
Right ascension	19h 37m 17.39324s[1]
Declination	+16° 27′ 46.0871″[1]
Apparent magnitude (V)	+5.64 to +5.67[2]
Characteristics
Evolutionary stage	horizontal branch[3]
Spectral type	G8 IIIvar[4]
U−B color index	+0.83[5]
B−V color index	+1.00[5]
Astrometry
Radial velocity (Rv)	−32.49±0.18[1] km/s
Proper motion (μ)	RA: +16.382±0.164[1] mas/yr Dec.: +14.364±0.135[1] mas/yr
Parallax (π)	5.6067±0.1173 mas[1]
Distance	580 ± 10 ly (178 ± 4 pc)
Absolute magnitude (MV)	−0.84±0.03[1]
Details
Mass	2.9[3] M☉
Radius	18.37+0.65 −0.88[1] R☉
Luminosity	184.9±4.6[1] L☉
Surface gravity (log g)	2.52[3] cgs
Temperature	4966+124 −85[1] K
Metallicity [Fe/H]	+0.02[3] dex
Rotational velocity (v sin i)	3.2[6] km/s
Age	520[3] Myr
Other designations
ε Sge, 4 Sge, BD+16°3918, HD 185194, HIP 96516, HR 7463, WDS J19373+1628A[7]
Database references
SIMBAD	data

This is an evolved, G-type giant star with a stellar classification of G8 IIIvar,^[4] where the 'var' suffix indicates a variable spectral feature. The star is about 520 million years old with about three times the mass of the Sun.^[3] It is radiating 185 times the Sun's luminosity from its photosphere at an effective temperature of 4,966 K.^[1]

Epsilon Sagittae is an optical binary, with a companion of magnitude 8.35 at an angular separation of 87.3 arc seconds along a position angle of 82°, as of 2013.^[10] The companion is actually a more distant giant star approximately 7,000 light-years from Earth, with a luminosity 1,800 times that of the Sun and also designated HD 232029.^[11]