HD 193307

HD 193307 (HR 7766; Gliese 9691) is the primary of a binary star located the southern constellation Telescopium. It has an apparent magnitude of 6.27,^[2] placing it near the limit for naked eye visibility, even under ideal conditions. The star is located relatively close at a distance of 102 light years based on Gaia DR3 parallax measurements,^[1] but it is receding with a heliocentric radial velocity of 16.9 km/s.^[7] At its current distance, HD 193307's brightness is diminished by 0.18 magnitudes due to extinction from interstellar dust^[18] and it has an absolute magnitude of +3.80.^[8] HD 193307 has a relatively high proper motion, moving at a rate of 437 mas/yr.^[19]

HD 193307

Location of HD 193307 (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Telescopium
A
Right ascension	20h 21m 41.03652s[1]
Declination	−49° 59′ 57.9001″[1]
Apparent magnitude (V)	6.27[2]
B
Right ascension	20h 21m 39.11678s[3]
Declination	−49° 59′ 47.2058″[3]
Apparent magnitude (V)	12.8[4]
Characteristics
A
Spectral type	F9 V[5]
U−B color index	–0.02[2]
B−V color index	+0.55[2]
B
Spectral type	M2.5[6]
Astrometry
A
Radial velocity (Rv)	16.9±0.65[7] km/s
Proper motion (μ)	RA: −357.855 mas/yr[1] Dec.: −250.604 mas/yr[1]
Parallax (π)	32.0547±0.0415 mas[1]
Distance	101.7 ± 0.1 ly (31.20 ± 0.04 pc)
Absolute magnitude (MV)	+3.80[8]
B
Radial velocity (Rv)	18.33±0.39[9] km/s
Proper motion (μ)	RA: −350.120 mas/yr[3] Dec.: −252.474 mas/yr[3]
Parallax (π)	32.0177±0.0193 mas[3]
Distance	101.87 ± 0.06 ly (31.23 ± 0.02 pc)
Details
A
Mass	1.15±0.16[10] M☉
Radius	1.49±0.07[11] R☉
Luminosity	2.605±0.006[1] L☉
Surface gravity (log g)	4.11±0.03[12] cgs
Temperature	6,059+96 −59[13] K
Metallicity [Fe/H]	−0.34±0.06[14] dex
Rotational velocity (v sin i)	<5[15] km/s
Age	7.55+0.62 −0.85[12] Gyr
Other designations
WDS J20217-5000AB[16]
A: 86 G. Telescopii[17], CD–50°12929, CPD−50°11341, FK5 3630, GC 28291, GJ 9691, HD 193307, HIP 100412, HR 7766, SAO 246546[16]
B: WT 703
Database references
SIMBAD	A
	B

There have been disagreements in the stellar classification of the object. Two sources give a class of F9 V,^[5] indicating that it is an ordinary F-type main-sequence star. David Stanley Evans gave it a slightly more evolved class of G2 IV-V,^[20] meaning that it is a G-type star with a luminosity class intermediate between a subgiant and main sequence star. Nancy Houk's spectral classification catalog lists HD 193307 as G0 V.^[21]

The accepted class for HD 193307 is F9 V.^[5] The object's current luminosity is 1.49 magnitudes above the ZAMS, indicating that HD 193307 is somewhat evolved.^[22] has 1.15 times the Sun's mass and a slightly enlarged radius of 1.49 R_☉.^[11] It radiates 2.61 times the luminosity of the Sun^[1] from its photosphere at an effective temperature of 6,059 K,^[13] which gives it the typical whitish-yellow hue of a late F-type star. At the age of 7.55 billion years,^[12] HD 193307 has nearly twice the Sun's age. The star is metal-deficient with an iron abundance 46% that of the Sun ([Fe/H] = −0.34)^[14] and it spins slowly with a projected rotational velocity lower than 5 km/s.^[15]

WT 703 is a 12th magnitude star located 21.3" away along a position angle of 300°. It has a class of M2.5, indicating that it is a M-type star.^[4] WT 703 is located around the same distance as HD 193307 and it has a similar proper motion.