66 Andromedae is a binary star[3] system in the northern constellation of Andromeda, near the northern border with Perseus. The designation is from the star catalogue of English astronomer John Flamsteed, first published in 1712. It has a combined apparent magnitude of 6.16,[2] which is near the lower limit of stars that are visible to the naked eye under good seeing conditions. An annual parallax shift of 18.3 mas[6] provides a distance estimate of 178 light years. The net radial velocity of the system is poorly constrained, but the pair appear to be moving closer to the Earth with a heliocentric radial velocity of around −5 km/s.[3]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 02h 27m 51.77815s[1] |
| Declination | +50° 34′ 11.9081″[1] |
| Apparent magnitude (V) | 6.16[2] (7.26/7.46)[3] |
| Characteristics | |
| Spectral type | F4 V[3] |
| B−V color index | 0.435 (4.2/4.5)[3] |
| Astrometry | |
| Radial velocity (Rv) | −5.3±4.3[3] km/s |
| Proper motion (μ) | RA: +31.700[1] mas/yr Dec.: −90.312[1] mas/yr |
| Parallax (π) | 18.2931 ± 0.0416 mas[1] |
| Distance | 178.3 ± 0.4 ly (54.7 ± 0.1 pc) |
| Absolute magnitude (MV) | 3.1±0.1/3.4±0.1[3] |
| Orbit[3] | |
| Period (P) | 10.989861±0.000024 d |
| Semi-major axis (a) | ≥ 6.9 Gm (9.9 R☉) |
| Eccentricity (e) | 0.19236±0.00057 |
| Periastron epoch (T) | 2,454,007.675±0.006 JD |
| Argument of periastron (ω) (secondary) | 250.55±0.18° |
| Semi-amplitude (K1) (primary) | 46.719±0.034 km/s |
| Semi-amplitude (K2) (secondary) | 48.083±0.038 km/s |
| Details[3] | |
| 66 And A | |
| Mass | 1.38 M☉ |
| Radius | 1.7±0.1 R☉ |
| Luminosity | 4.9±0.5 L☉ |
| Surface gravity (log g) | 4.21[4] cgs |
| Temperature | 6,627±225[4] K |
| Metallicity [Fe/H] | −0.14±0.08[2] dex |
| Rotational velocity (v sin i) | 4.2±1.0 km/s |
| Age | 1.273[4] Gyr |
| 66 And B | |
| Radius | 1.5±0.1 R☉ |
| Luminosity | 3.8±0.4 L☉ |
| Rotational velocity (v sin i) | 4.4±1.0 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
The variable velocity of this system was reported by Reynold K. Young from the David Dunlap Observatory in 1945. This is a double-lined spectroscopic binary system with an orbital period of 11 days and an eccentricity of 0.19.[3] The two components are similar stars, each of 7th[3] magnitude, with a combined stellar classification of F4 V,[3] matching that of an F-type main sequence star. The system is around 1.3[4] billion years old and both stars are spinning slowly with a projected rotational velocity of around 4–5 km/s.[3]
References
edit- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ 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 g h i j k l m Fekel, Francis C.; et al. (April 2010), "New Precision Orbits of Bright Double-lined Spectroscopic Binaries. IV. 66 Andromedae, HR 6979, and HR 9059" (PDF), The Astronomical Journal, 139 (4): 1579−1591, Bibcode:2010AJ....139.1579F, doi:10.1088/0004-6256/139/4/1579, hdl:2152/34408, S2CID 10950822.
- ^ a b c d 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, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ^ "66 And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-02.
- ^ 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.