Zeta Horologii

Zeta Horologii

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Horologium
Right ascension	02^h 40^m 39.61286^s[1]
Declination	−54° 32′ 59.6836″[1]
Apparent magnitude (V)	5.20[2]
Characteristics
Spectral type	F6 V[3] (F2 V + F5 V)[4]
B−V color index	+0.42[2]
Astrometry
Radial velocity (Rv)	5.8[3] km/s
Proper motion (μ)	RA: +32.86[1] mas/yr Dec.: +4.96[1] mas/yr
Parallax (π)	20.37 ± 0.21 mas[1]
Distance	160 ± 2 ly (49.1 ± 0.5 pc)
Absolute magnitude (MV)	+1.76[5]
Orbit[4]
Period (P)	12.9274 d
Eccentricity (e)	0.25
Periastron epoch (T)	7.361±0.046
Argument of periastron (ω) (secondary)	78.6±0.13°
Semi-amplitude (K1) (primary)	58.1±1.37 km/s
Semi-amplitude (K2) (secondary)	66.1±1.56 km/s
Details
ζ Hor A
Mass	1.43[6] M☉
Luminosity	16.7[5] L☉
Surface gravity (log g)	3.74[7] cgs
Temperature	6,702[7] K
Metallicity [Fe/H]	−0.07[7] dex
Rotational velocity (v sin i)	8.0±1.2[3] km/s
Age	1.50[7] Gyr
ζ Hor B
Mass	1.26[6] M☉
Other designations
ζ Hor, CPD−55° 446, FK5 1076, HD 16920, HIP 12484, HR 802, SAO 232857[8]
Database references
SIMBAD	data

Zeta Horologii, Latinized from ζ Horologii, is a yellow-white-hued binary star system in the southern constellation of Horologium. It is visible to the naked eye with a combined apparent visual magnitude of 5.20.^[2] Based upon an annual parallax shift of 20.37 mas as seen from Earth,^[1] it is located around 160 light-years from the Sun.

This system was determined to be a double-lined spectroscopic binary by J. H. Moore in 1911−12. The first orbital elements were published by J. Sahade and C. A. Hernández in 1964, who found it consisted of two F-type main-sequence stars of probable stellar classifications F2 V and F5 V. The pair orbit each other with a period of 12.9274 days and an eccentricity of 0.25.^[4] The system displays an infrared excess at a wavelength of 24 μm but not at 70 μm, yielding a derived temperature of 260 K. This suggests a circumbinary debris disk orbiting at a distance of less than 4.8 AU from the star system.^[9]

References

1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
2. Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C.
3. Torres, C. A. O.; et al. (December 2006), "Search for associations containing young stars (SACY). I. Sample and searching method", Astronomy and Astrophysics, 460 (3): 695–708, arXiv:astro-ph/0609258, Bibcode:2006A&A...460..695T, doi:10.1051/0004-6361:20065602, S2CID 16080025.
4. Sahade, J.; Hernández, C. A. (February 1964), "The spectroscopic binary ζ Horologii", Annales d'Astrophysique, 27: 11, Bibcode:1964AnAp...27...11S.
5. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
6. Tokovinin, A.; et al. (May 2006), "Tertiary companions to close spectroscopic binaries", Astronomy and Astrophysics, 450 (2): 681–693, arXiv:astro-ph/0601518, Bibcode:2006A&A...450..681T, doi:10.1051/0004-6361:20054427, S2CID 8899546.
7. Casagrande, L.; et al. (2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy & Astrophysics, 530 (A138): 21, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276, S2CID 56118016.
8. "zet Hor -- Spectroscopic binary", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-04-25.
9. Trilling, D. E.; et al. (April 2007), "Debris disks in main-sequence binary systems", The Astrophysical Journal, 658 (2): 1264–1288, arXiv:astro-ph/0612029, Bibcode:2007ApJ...658.1289T, doi:10.1086/511668, S2CID 14867168.