Astronomy:Eta Horologii
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Short description: Binary star system in the constellation Horologium
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Horologium |
| Right ascension | 02h 37m 24.37297s[1] |
| Declination | −52° 32′ 35.0855″[1] |
| Apparent magnitude (V) | 5.31[2] |
| Characteristics | |
| Spectral type | A6 V + F0 V[3] |
| B−V color index | +0.27[2] |
| Astrometry | |
| Radial velocity (Rv) | −3.0±7.4[4] km/s |
| Proper motion (μ) | RA: +112.70[1] mas/yr Dec.: +3.73[1] mas/yr |
| Parallax (π) | 21.95 ± 1.10[1] mas |
| Distance | 149 ± 7 ly (46 ± 2 pc) |
| Absolute magnitude (MV) | 2.13[5] |
| Orbit[6] | |
| Period (P) | 3.01±0.18 yr |
| Semi-major axis (a) | 0.0231±0.0014″ |
| Eccentricity (e) | 0.16±0.14 |
| Details | |
| η Hor A | |
| Mass | 1.75[7] M☉ |
| Luminosity | 12.6[8] L☉ |
| Surface gravity (log g) | 4.21[9] cgs |
| Temperature | 7,552±257[9] K |
| Rotational velocity (v sin i) | 6.6±2.2[5] km/s |
| Age | 474[9] Myr |
| η Hor B | |
| Mass | 1.65[7] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Horologii (η Horologii, η Hor) is a binary star system[3] in the southern constellation of Horologium. It is visible to the naked eye with a combined apparent visual magnitude of 5.31.[2] Based upon an annual parallax shift of 21.95 mas as seen from Earth,[1] it is located around 149 light years from the Sun.
The orbit for this pair is not yet well constrained. They appear to have an orbital period of three years and an eccentricity of roughly 0.16.[6] As of 2012, the pair have an angular separation of 78.7 mas, which corresponds to a projected separation of 3.6 AU.[3] The primary member, component A, is an A-type main sequence star with a stellar classification of A6 V. The secondary, component B, has an inferred class of F0 V, which would indicate it is an F-type main sequence star.[3]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J.
- ↑ 3.0 3.1 3.2 3.3 Marion, L. et al. (October 2014), "Searching for faint companions with VLTI/PIONIER. II. 92 main sequence stars from the Exozodi survey", Astronomy & Astrophysics 570: 12, doi:10.1051/0004-6361/201424780, A127, Bibcode: 2014A&A...570A.127M.
- ↑ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics 546: 14, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D.
- ↑ 5.0 5.1 Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics 542: A116, doi:10.1051/0004-6361/201118724, Bibcode: 2012A&A...542A.116A.
- ↑ 6.0 6.1 Malkov, O. Yu. et al. (2012), "Dynamical Masses of a Selected Sample of Orbital Binaries", Astronomy & Astrophysics 546: 5, doi:10.1051/0004-6361/201219774, A69, Bibcode: 2012A&A...546A..69M.
- ↑ 7.0 7.1 Asensio-Torres, R.; Janson, M.; Bonavita, M.; Desidera, S.; Thalmann, C.; Kuzuhara, M.; Henning, Th.; Marzari, F. et al. (2018). "SPOTS: The Search for Planets Orbiting Two Stars. III. Complete sample and statistical analysis". Astronomy & Astrophysics 619: A43. doi:10.1051/0004-6361/201833349. Bibcode: 2018A&A...619A..43A.
- ↑ McDonald, I. et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–57, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M
- ↑ 9.0 9.1 9.2 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal 804 (2): 146, doi:10.1088/0004-637X/804/2/146, Bibcode: 2015ApJ...804..146D.
- ↑ "eta Hor -- Double or multiple star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=eta+Hor, retrieved 2017-04-25.
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