Epsilon Sagittae

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
Spectral type G8 IIIvar[3]
U−B color index +0.83[4]
B−V color index +1.00[4]
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]
Distance580 ± 10 ly
(178 ± 4 pc)
Absolute magnitude (MV)−0.84±0.03[1]
Details[5]
Mass3.09 M☉
Radius18.37+0.65
−0.88[1] R☉
Luminosity184.9±4.6[1] L☉
Surface gravity (log g)2.44 cgs
Temperature4966+124
−85[1] K
Metallicity [Fe/H]+0.03 dex
Rotational velocity (v sin i)3.2 km/s
Age331 Myr
Other designations
ε Sge, 4 Sge, BD+16°3918, HD 185194, HIP 96516, HR 7463, WDS J19373+1628A[6]
Database references
SIMBADdata

Epsilon Sagittae (ε Sagittae) is a solitary,[7] 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,[8] 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.[3]

This is an evolved, G-type giant star with a stellar classification of G8 IIIvar,[3] where the 'var' suffix indicates a variable spectral feature. The star is about 331 million years old with three times the mass of the Sun.[5] 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.[9] 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.[10]

  1. ^ a b c d e f g h i j k Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b Cite error: The named reference VSX2005 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Takeda2008 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Argue1966 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference takeda14 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Mason2014 was invoked but never defined (see the help page).
  10. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.