35 Sextantis (68 G. Sextantis; HD 92841; HR 4193), or simply 35 Sex, is a triple star system located in the equatorial constellation Sextans. The primary has an apparent magnitude of 6.09,^[2] making it barely visible to the naked eye, even under ideal conditions. The companion has an apparent magnitude of 7.01,^[2] making it readily visible in binoculars, but not to the naked eye. The system is located relatively far at a distance of approximately 700 light-years but it is drifting closer with a combined heliocentric radial velocity of −2.18 km/s.^[17]

Quick Facts Apparent magnitude (V), Characteristics ...

35 Sextantis

Location of 35 Sex on the map (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Sextans
A
Right ascension	10h 43m 20.92086s[1]
Declination	+04° 44′ 51.6121″[1]
Apparent magnitude (V)	6.09±0.01[2]
B
Right ascension	10h 43m 20.52732s[3]
Declination	+04° 44′ 48.2184″[3]
Apparent magnitude (V)	7.01±0.01[2]
Characteristics
U−B color index	+1.09[4]
B−V color index	+1.17[4]
A
Spectral type	K2.5 III[5]
B
Spectral type	K1 II-III[6]
Astrometry
A
Radial velocity (Rv)	−3.15±0.16[7] km/s
Proper motion (μ)	RA: +22.430 mas/yr[1] Dec.: −33.285 mas/yr[1]
Parallax (π)	4.6773 ± 0.1457 mas[1]
Distance	700 ± 20 ly (214 ± 7 pc)
B
Radial velocity (Rv)	−1.49±0.98[7] km/s
Proper motion (μ)	RA: +24.384 mas/yr[3] Dec.: −37.384 mas/yr[3]
Parallax (π)	4.5442 ± 0.15 mas[3]
Distance	720 ± 20 ly (220 ± 7 pc)
Orbit[8]
Primary	A
Companion	B
Period (P)	23,302 yr
Semi-major axis (a)	6.80" (1,460 AU)
Orbit[9]
Primary	Ba
Companion	Bb
Period (P)	1,568.7±2.2 d
Semi-major axis (a)	0.021" (4.64 AU)
Eccentricity (e)	0.388±0.057
Periastron epoch (T)	2,451,911±27 JD
Argument of periastron (ω) (secondary)	311.8±3.3°
Semi-amplitude (K1) (primary)	5.55±0.15 km/s
Details
A
Mass	2.45[8] M☉
Radius	25.39+0.8 −2.2[10] R☉
Luminosity	240±7[10] L☉
Temperature	4,512±122[11] K
Metallicity [Fe/H]	−0.17[12] dex
Rotational velocity (v sin i)	3.7±0.3[7] km/s
Ba
Mass	2.44[8] M☉
Radius	10.15+0.34 −0.30[13] R☉
Luminosity	57.2±1.2[13] L☉
Temperature	5,030±122[11] K
Metallicity [Fe/H]	−0.16[12] dex
Rotational velocity (v sin i)	4.1±0.5[7] km/s
Bb
Mass	0.58[8] M☉
Other designations
10 H. Sextantis,[14] 35 Sex, 68 G. Sextantis[15], AG+05°1556, BD+05°2384, GC 14745, HD 92841, HIP 52452, HR 4193, SAO 118449, CCDM J10433+0443, TIC 374350811[16]
Database references
SIMBAD	The system
	A
	B

Close

The system was first observed by Friedrich Georg Wilhelm von Struve in 1821.^[18] The separation between the A and B component was initially 7.90 arcseconds,^[18] but it has since decreased to 6.62".^[19] Thanks to this separation, the components 35 Sextantis can be distinguished using a telescope. Observations from Tokovinin & Gorynya (2007) revealed that the B component is a single-lined spectroscopic binary.^[9] The primary and secondary both take 23,302 years to orbit each other while the secondary and its close companion take 1,568 days to revolve around each other in a relatively eccentric orbit.^[9]

35 Sextantis A has a stellar classification of K2.5 III,^[5] indicating that it is an evolved K-type giant star that has exhausted hydrogen at its core and left the main sequence. 35 Sextantis B has a classification of K1 II-III,^[6] indicating that it is a hotter, more evolved K-type star that has the luminosity class intermediate between a bright giant and giant star. The primary has 2.45 times the mass of the Sun^[8] but it has expanded to 25.39 times the radius of the Sun.^[10] It radiates 240 times the luminosity of the Sun^[10] from its enlarged photosphere at an effective temperature of 4,512 K,^[11] giving it an orange-hued when viewed in the night sky.

The secondary has a similar mass to the primary^[8] but it is smaller, having a radius 10.15 times that of the Sun.^[13] 35 Sextantis B radiates 57.2 times the luminosity of the Sun^[13] from its photosphere at an effective temperature of 5030 K.^[11] Both stars are metal deficient with iron abundances of [Fe/H] = −0.17 and [Fe/H] = −0.16 respectively.^[12] They spin modestly with projected rotational velocities of 3.7 km/s and 4.1 km/s.^[7] The close companion has a mass 58% that of the Sun's,^[8] suggesting that it may be a K-type main-sequence star.