Y Sextantis

Y Sextantis
Observation data Epoch J2000.0 Equinox J2000.0
Possible architecture for Y Sextantis' multiple system
Constellation	Sextans
Right ascension	10^h 02^m 47.9589^s
Declination	+01° 05′ 40.346″
Apparent magnitude (V)	9.97
Characteristics
Spectral type	F8V/F8.5V-VI
Astrometry

Distance	361.4 ly (110.86 pc)

Details

Mass	1.21/0.22^[1] M_☉
Radius	1.4/0.85 R_☉
Luminosity	2.6/0.96 L_☉
Temperature	≈6200 K

Other designations
Y Sex, BD+01 2394, HIP 49217, HD 87079

Y Sextantis (Y Sex) is a W Ursae Majoris variable eclipsing contact binary star system located roughly at 360 light years from the Sun, whose two component stars share a common outer layer. Because the two components share their outer layers as the components of W Ursae Majoris do, they have the same stellar classification, and are classified as yellow F-type main sequence dwarfs. The components take 0.419822800 days (roughly 10 hours) to revolve around common barycentre. Orbital period variations would suggest the presence of additional perturbing objects, one of them likely substellar.

Perturbing third (and fourth?) body

Orbital period variations suggest the presence of one more perturbing unseen object.^[1] The authors He & Qian have estimated two possible orbital periods and minimum masses for unseen companions: the former cyclic oscillation would occur every 51.22 years (with amplitude of 0.0218 days) being caused by a low-mass stellar companion (likely a M dwarf star), whereas the latter would consist in a 32.1 years period and the unseen object could likely be substellar.

The Y Sextantis planetary system
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b (unconfirmed)	≥240 (0.24 Solar masses) M_J	49.0±3.9	≈18695	?	—	—
c (unconfirmed)	≥43 M_J	58.9±6.7	≈11716	?	—	—

References

1 2 He & Qian (2007). "An Orbital Period Investigation of the WUMa-Type Binary Y Sextantis". Publications of the Astronomical Society of Japan. 59 (6): 1115–1119. arXiv:0908.4521. Bibcode:2007PASJ...59.1115H. doi:10.1093/pasj/59.6.1115.

Stars of Sextans

Bayer	α β γ δ ε

Flamsteed	3 4 5 6 7 9 12 13 14 16 17 18 19 20 21 23 24 25 26 27 31 32 33 34 35 36 39 40 41

Variable	S T Y RW SW VY

HR	3879 3901 3907 3915 3959 4000 4034 4059 4060 4085 4092 4109 4122 4224 4233 4240

HD	85461 86081 86341 90057 92788

Gliese	Gliese 382 Gliese 393

Other	BD+08°2823 FIRST J102347.6+003841 LHS 292 PG 1026+002 PG 1047+003 Population III stars Cosmos Redshift 7 galaxy WASP-43

List

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