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

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

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

References

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v t e Constellation of Octans
List of stars in Octans Octans in Chinese astronomy
Stars	Bayer α β γ γ γ δ ε ζ η θ ι κ λ μ μ ν ξ ο π π ρ σ (Polaris Australis) τ υ φ χ ψ ω Variable R BQ CK CW FT HR 47 512 525 4595 6837 6912 7698 7785 7812 8234 8380 8432 8526 8577 8786 8935 8957 8995 HD 142022 166066 212301 Other Gliese 877 LHS 475 TOI-4342 W2150AB
Exoplanets 2MASS J2126–8140 HD 142022 Ab HD 212301 b LHS 475 b
Galaxies	NGC 2573 7095 7098 Other PGC 10922
Category

• G-type bright giants
• Octans
• Astrometric binaries
• Double stars
• Henry Draper Catalogue objects
• Durchmusterung objects
• Hipparcos objects
• Bright Star Catalogue objects
• Gould objects