HD 193721

HD 193721
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Octans
Right ascension 20h 33m 17.6366s[1]
Declination −80° 57′ 53.5944″[1]
Apparent magnitude (V) 5.77±0.01[2]
Characteristics
Spectral type G6/8 II[3]
U−B color index +0.85[4]
B−V color index +1.14[4]
Astrometry
Radial velocity (Rv)8.6±0.7[5] km/s
Proper motion (μ) RA: +9.794 mas/yr[1]
Dec.: −16.081 mas/yr[1]
Parallax (π)4.2823 ± 0.165 mas[1]
Distance760 ± 30 ly
(234 ± 9 pc)
Absolute magnitude (MV)−0.24[6]
Details
Mass3.49[7] M☉
Radius24.38[8] R☉
Luminosity300±5[9] L☉
Surface gravity (log g)2.14±0.02[1] cgs
Temperature4953±122[8] K
Metallicity [Fe/H]−0.15[10] dex
Rotational velocity (v sin i)2.7±1.1[11] km/s
Other designations
47 G. Octantis[12], CPD−81°901, FK5 3994, GC 28453, HD 193721, HIP 101427, HR 7785, SAO 258861, WDS J20333-8058A[13]
Database references
SIMBADdata

HD 193721 (HR 7785) is an astrometric binary[14] in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.77,[2] allowing it to be faintly seen with the naked eye. Parallax measurements place the system 760 light years[1] away from the Solar System and it is currently receding with a heliocentric radial velocity 8.6 km/s.[5]

HD 193721 has a stellar classification of G6/8 II[3] — intermediate between a G6 and 8 bright giant. At present it has 3.49 times the mass of the Sun,[7] but has expanded to 24.4 times its girth.[8] It shines with a luminosity of 300 L☉[9] from its enlarged photosphere at an effective temperature of 4,953 K,[8] giving a yellow hue. HD 193721 is metal deficient with an iron abundance 71% that of the Sun[10] and spins leisurely with a projected rotational velocity of 2.7 km/s.[11]

The system has an companion designated CPD −81°900. The object has a spectral classification of F8[15] and is located 25.5″ along a position angle of 0° (as of 1998).[16] CPD −81°900 is a foreground object, having a higher parallax[17] and different proper motion.[16]

  1. ^ a b c d e f Cite error: The named reference EDR3 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Tycho2000 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Houk1975 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Johnson1966 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Kervella2021 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference Stassun2019 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Anders2019 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference DeMed2014 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Gould1879 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Frankowski2006 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Stoy1968 was invoked but never defined (see the help page).
  16. ^ a b Cite error: The named reference Mason2001 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference EDR3B was invoked but never defined (see the help page).