HD 118889
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes[1] |
| Right ascension | 13h 39m 34.61613s[2] |
| Declination | +10° 44′ 46.5827″[2] |
| Apparent magnitude (V) | 5.57[1] (6.35 + 6.47)[3] |
| Characteristics | |
| Evolutionary stage | Main sequence[4][5] |
| Spectral type | F0V[6] |
| U−B color index | +0.045[7] |
| B−V color index | +0.33[7] |
| Astrometry | |
| Radial velocity (Rv) | −25.9±1.9[8] km/s |
| Proper motion (μ) | RA: −114.96[2] mas/yr Dec.: −11.74[2] mas/yr |
| Parallax (π) | 16.67±0.58 mas[2] |
| Distance | 196 ± 7 ly (60 ± 2 pc) |
| Absolute magnitude (MV) | +2.40[9] |
| Orbit[10] | |
| Period (P) | 22.460±0.019 yr |
| Semi-major axis (a) | 0.19983±0.00055″ |
| Eccentricity (e) | 0.5450±0.0022 |
| Inclination (i) | 43.50±0.40° |
| Longitude of the node (Ω) | 34.58±0.52° |
| Periastron epoch (T) | B 1929.850±0.024 |
| Argument of periastron (ω) (secondary) | 359.93±0.79° |
| Details | |
| A | |
| Mass | 1.59[11] M☉ |
| B | |
| Mass | 1.55[11] M☉ |
| Other designations | |
| BD+11°2589, HD 118889, HIP 66640, HR 5138, SAO 100654, ADS 8987, WDS 13396+1045, BU 612 | |
| Database references | |
| SIMBAD | data |
HD 118889 is a binary star system in the northern constellation of Boötes. It is faintly visible to the naked eye as a point of light with an apparent visual magnitude of 5.57.[1] The system is located at a distance of approximately 196 light years from the Sun based on stellar parallax,[2] but is drifting closer with a radial velocity of −26 km/s.[8]
The binary components of this system were first measured by S. W. Burnham in 1878 and it was given the discovery code BU 612.[12] The pair are orbiting each other with a period of 22.46 years with an eccentricity (ovalness) of 0.545. The primary component is magnitude 6.35, with the secondary slightly fainter at magnitude 6.47.[3]
A third star, 3.5″ away, is a 12th-magnitude common-proper-motion companion. Any orbit would take over a thousand years.[11]
References
[edit]- ^ a b c 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
- ^ a b c d e f van Leeuwen, F. (November 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
- ^ a b Malkov, O. Yu.; et al. (2012), "Dynamical Masses of a Selected Sample of Orbital Binaries", Astronomy & Astrophysics, 546: 5, Bibcode:2012A&A...546A..69M, doi:10.1051/0004-6361/201219774, A69
- ^ Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377[permanent dead link]
- ^ Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789
- ^ Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298
- ^ a b Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data. SIMBAD, Bibcode:1986EgUBV........0M
- ^ a b Holmberg, J.; et al. (2007), "The Geneva-Copenhagen survey of the Solar neighbourhood. II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk", Astronomy & Astrophysics, 475 (2): 519–537, arXiv:0707.1891, Bibcode:2007A&A...475..519H, doi:10.1051/0004-6361:20077221, S2CID 119054949
- ^ Reiners, Ansgar (January 2006), "Rotation- and temperature-dependence of stellar latitudinal differential rotation", Astronomy and Astrophysics, 446 (1): 267–277, arXiv:astro-ph/0509399, Bibcode:2006A&A...446..267R, doi:10.1051/0004-6361:20053911, S2CID 8642707
- ^ "Sixth Catalog of Orbits of Visual Binary Stars", United States Naval Observatory, retrieved 2021-04-01
- ^ a b c Tokovinin, Andrei (2018), "The Updated Multiple Star Catalog", The Astrophysical Journal Supplement Series, 235 (1): 6, arXiv:1712.04750, Bibcode:2018ApJS..235....6T, doi:10.3847/1538-4365/aaa1a5
- ^ Mason, Brian D.; et al. (February 1999), "Binary Star Orbits from Speckle Interferometry. I. Improved Orbital Elements of 22 Visual Systems", The Astronomical Journal, 117 (2): 1023–1036, Bibcode:1999AJ....117.1023M, doi:10.1086/300748, S2CID 122382211
