Omega Sagittarii

Omega Sagittarii
Location of ω Sagittarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 19h 55m 50.36255s[1]
Declination −26° 17′ 57.6933″[1]
Apparent magnitude (V) 4.70[2]
Characteristics
Evolutionary stage subgiant
Spectral type G5 IV[3]
U−B color index +0.32[4]
B−V color index +0.748±0.015[1]
R−I color index +0.37[4]
Astrometry
Radial velocity (Rv)−16.22±0.43[1] km/s
Proper motion (μ) RA: 203.96[5] mas/yr
Dec.: 74.40[5] mas/yr
Parallax (π)42.7159 ± 0.5538 mas[1]
Distance76.4 ± 1.0 ly
(23.4 ± 0.3 pc)
Absolute magnitude (MV)2.64[2]
Orbit[6]
Period (P)1,712.74±0.29 d
Semi-major axis (a)≥ 1.1044 ± 0.0051 AU
Eccentricity (e)0.8200±0.0012
Periastron epoch (T)57549.31±0.20 HJD
Argument of periastron (ω)
(secondary)		141.17±0.33°
Semi-amplitude (K1)
(primary)		12.255±0.041 km/s
Details[7]
Mass1.52+0.08
−0.06 M☉
Radius2.87+0.37
−0.34[1] R☉
Luminosity7.1±0.1[1] L☉
Surface gravity (log g)3.64±0.05 cgs
Temperature5,499±91 K
Metallicity [Fe/H]0.06±0.06 dex
Rotational velocity (v sin i)5.6[8] km/s
Age3.00+0.13
−0.61 Gyr
Other designations
Terebellum, ψ Sgr, 58 Sagittarii, CPD−26°6880, FK5 1629, GC 27583, HD 188376, HIP 98066, HR 7597, SAO 188722, PPM 270451[9]
Database references
SIMBADdata

Omega Sagittarii, which is Latinized from ω Sagittarii, is a binary star system in the constellation of Sagittarius,[9] near the eastern constellation border with Capricornus. It is formally named Terebellum /tɛrɪˈbɛləm/.[10][11] This system has a yellow hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.70.[2] It is located at a distance of 76 light years away from the Sun based on parallax,[1] and is drifting closer with a radial velocity of −16 km/s.[1] The position of this star near the ecliptic means it is subject to lunar occultations.[12]

The members of this system orbit each other with a period of 4.6892 yr and an eccentricity of 0.82.[6] The visible component is a G-type subgiant star with a stellar classification of G5 IV.[3] It is three[7] billion years old and is spinning with a projected rotational velocity of 5.6 km/s.[8] The star is radiating seven[1] times the luminosity of the Sun from its photosphere at an effective temperature of 5,499 K.[7]

  1. ^ a b c d e f g h i j Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference perkins1989 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference bsc1 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Fekel2018 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference AguileraGómez2018 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Earle2017 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference IAU-LSN was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference OED was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Evans1986 was invoked but never defined (see the help page).