64 Piscium

64 Piscium is the Flamsteed designation for a close binary star system in the zodiac constellation of Pisces. It can be viewed with the naked eye, with the components having a combined apparent visual magnitude of 5.07.[2] An annual parallax shift of 42.64 mas provides a distance estimate of 46.5 light years. The system is moving further from the Sun with a radial velocity of +3.76 km/s.[4]

64 Piscium
Observation data
Epoch J2000      Equinox J2000
Constellation Pisces
Right ascension 00h 48m 58.70805s[1]
Declination +16° 56′ 26.3132″[1]
Apparent magnitude (V) 5.07[2]
Characteristics
Spectral type F8 V + F8 V[3]
B−V color index 0.502[2]
Astrometry
Radial velocity (Rv)+3.76±0.08[4] km/s
Proper motion (μ) RA: −2.87[1] mas/yr
Dec.: −202.05[1] mas/yr
Parallax (π)42.64 ± 0.27[1] mas
Distance76.5 ± 0.5 ly
(23.5 ± 0.1 pc)
Absolute magnitude (MV)3.22[5]
Orbit[6]
Period (P)13.8244906±0.000043 d
Semi-major axis (a)6.545±0.0133 mas (0.073953±0.000048 AU)
Eccentricity (e)0.23657±0.00063
Inclination (i)73.92±0.80°
Longitude of the node (Ω)207.41±0.65°
Periastron epoch (T)50905.984 ± 0.015 MJD
Argument of periastron (ω)
(secondary)		203.057±0.073°
Semi-amplitude (K1)
(primary)		57.552±0.037 km/s
Semi-amplitude (K2)
(secondary)		59.557±0.038 km/s
Details[3]
64 Psc Aa
Mass1.223±0.021 M☉
Radius1.25±0.08 R☉
Luminosity2.12 L☉
Temperature6,250±150 K
Metallicity [Fe/H]0.00[7] dex
Age6.81[8] Gyr
64 Psc Ab
Mass1.170±0.018 M☉
Radius1.18±0.10 R☉
Luminosity1.85 L☉
Temperature6,200±200 K
Other designations
64 Psc, BD+16° 76, FK5 1020, GJ 9031, HD 4676, HIP 3810, HR 225, SAO 92099, WDS J00490+1656A[9]
Database references
SIMBADdata

This is a double-lined spectroscopic binary system consisting of two similar components[3] designated Aa and Ab.[10] The initial orbital elements were determined by Abt and Levy (1976), giving an orbital period of 13.8 days. In Boden et al. (1999), the full set of orbital elements were derived using measurements with the Palomar Testbed Interferometer.[11] Nadal et al. (1979) suggested that some variation in the measurements may be caused by a third component in the system,[12] but this was not supported by the results from Boden et al. (1999).[11] In 2005, Maciej Konacki pioneered a new technique for accurately determining the radial velocity of a double-lined binary system, which allowed the elements to be further refined. This yielded an orbital period of 13.82449 days, an eccentricity of 0.2366, and an angular semimajor axis of 6.55 mas.[6]

Both stars in this system have a spectrum matching a stellar classification of F8 V,[3] indicating they are ordinary F-type main-sequence stars that are generating energy via hydrogen fusion at their cores. The orbital measurements of this system allows the masses of the two stars to be determined accurately: the primary component has 1.22 times the mass of the Sun while the secondary has 1.17 times the Sun's mass.[3] Both stars are larger and brighter than the Sun, with higher temperature photospheres − having effective temperatures of around 6,200 K compared to 5,772 K for the Sun.[13] The age of the system is estimated as 6.8[8] billion years and they have a similar element abundance as the Sun.[7]

In 2010, the system was identified as a debris disk candidate based upon the detection of an infrared excess at a wavelength of 24 μm.[14] This dust has a mean temperature of 300 K and is orbiting at a radius of 1.7 AU,[15] compared to a projected linear separation of 0.23 AU for the components.[10]

The Washington Double Star Catalog lists two additional visual components. Component B is a magnitude 12.6 star at an angular separation of 77 arcseconds from the primary system. Component C is magnitude 13.0 and is located 71 arcseconds away. It is unknown if either is gravitationally bound to 64 Piscium Aab, but if they are then the projected separations are about 1,800 AU with an orbital period of around 50,000 years.[11]

References
  1. 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.
  2. ESA (1997). "The HIPPARCOS and TYCHO catalogues. Astrometric and photometric star catalogues derived from the ESA HIPPARCOS Space Astrometry Mission". The Hipparcos and Tycho catalogues. Astrometric and photometric star catalogues derived from the ESA Hipparcos Space Astrometry Mission. 1200. Bibcode:1997ESASP1200.....E.
  3. Torres, G.; Andersen, J.; Giménez, A. (February 2010), "Accurate masses and radii of normal stars: modern results and applications", The Astronomy and Astrophysics Review, 18 (1–2): 67–126, arXiv:0908.2624, Bibcode:2010A&ARv..18...67T, doi:10.1007/s00159-009-0025-1.
  4. 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, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  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.
  6. Konacki, Maciej (June 2005), "Precision Radial Velocities of Double-lined Spectroscopic Binaries with an Iodine Absorption Cell", The Astrophysical Journal, 626 (1): 431−438, arXiv:astro-ph/0410389, Bibcode:2005ApJ...626..431K, doi:10.1086/429880.
  7. Casagrande, L.; et al. (June 2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy and Astrophysics, 530: A138, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276.
  8. Vican, Laura (June 2012), "Age Determination for 346 Nearby Stars in the Herschel DEBRIS Survey", The Astronomical Journal, 143 (6): 135, arXiv:1203.1966, Bibcode:2012AJ....143..135V, doi:10.1088/0004-6256/143/6/135.
  9. "64 Psc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-18.
  10. Raghavan, Deepak; et al. (September 2010), "A Survey of Stellar Families: Multiplicity of Solar-type Stars", The Astrophysical Journal Supplement, 190 (1): 1–42, arXiv:1007.0414, Bibcode:2010ApJS..190....1R, doi:10.1088/0067-0049/190/1/1 For the adopted physical separation, see Table 11 in the appendix.
  11. Boden, A. F.; et al. (December 1999), "The Visual Orbit of 64 Piscium", The Astrophysical Journal, 527 (1): 360−368, arXiv:astro-ph/9905207, Bibcode:1999ApJ...527..360B, doi:10.1086/308067.
  12. Nadal, R.; et al. (February 1979), "64 Piscium, a double line spectroscopic binary - Discussion on orbital elements", Astronomy and Astrophysics Supplement Series (in French), 35: 203−212, Bibcode:1979A&AS...35..203N.
  13. Williams, David R. (December 16, 2016), Sun Fact Sheet, NASA Goddard Space Flight Center, retrieved 2018-01-21.
  14. Koerner, D. W.; et al. (February 2010), "New Debris Disk Candidates Around 49 Nearby Stars" (PDF), The Astrophysical Journal Letters, 710 (1): L26–L29, Bibcode:2010ApJ...710L..26K, doi:10.1088/2041-8205/710/1/L26.
  15. Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series, 225 (1): 24, arXiv:1606.01134, Bibcode:2016ApJS..225...15C, doi:10.3847/0067-0049/225/1/15, 15.
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