Psi Sagittarii

Psi Sagittarii
Diagram showing star positions and boundaries of the Sagittarius constellation and its surroundings
Location of ψ Sagittarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 19h 15m 32.42658s[1]
Declination −25° 15′ 24.0569″[1]
Apparent magnitude (V) +4.86[2]
Characteristics
Spectral type K2 III + A9 III + A3 V[3]
B−V color index 0.569±0.006[2]
Astrometry
Radial velocity (Rv)−11.43±1.47[4] km/s
Proper motion (μ) RA: +45.50[1] mas/yr
Dec.: −31.08[1] mas/yr
Parallax (π)10.93 ± 0.31 mas[1]
Distance298 ± 8 ly
(91 ± 3 pc)
Absolute magnitude (MV)0.06[2]
Orbit[5]
Period (P)7,319 d
Eccentricity (e)0.51
Periastron epoch (T)2442418.795 JD
Argument of periastron (ω)
(secondary)		2.6°
Semi-amplitude (K1)
(primary)		10.0 km/s
Semi-amplitude (K2)
(secondary)		13.8 km/s
Details
A
Mass2.10[6] M☉
Luminosity84[2] L☉
Ba/Bb
Mass1.70/2.70 M☉
Other designations
ψ Sgr, 42 Sgr, CPD−27° 6737, HD 179950, HIP 94643, HR 7292, SAO 187882, WDS J19155-2515[7]
Database references
SIMBADdata

Psi Sagittarii, which is Latinized from ψ Sagittarii, is a triple star[8] system in the zodiac constellation of Sagittarius. The star system is located at a distance of 298 light years from the Earth based on parallax, but is drifting closer with a heliocentric radial velocity of −12 km/s.[4] The system is faintly visible to the naked eye has a combined apparent visual magnitude of +4.86.[2]

The inner pair of this triple star system, components Ba and Bb, have an orbital period of 10.78 days and an eccentricity of 0.47.[8] The pair consist of an A-type giant and a less evolved A-type main-sequence star with stellar classifications of A9 III + A3 V,[3] respectively. These in turn share an orbit with the primary, component A, having a period of 20 years and an eccentricity of 0.51.[5] The last is an orange-hued K-type giant with a class of K2 III.[3]

  1. ^ a b c d e Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Docobo2006 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Pourbaix2004 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Tokovinin2008 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).