HD 216446

HD 216446 is a binary star[8] system in the northern circumpolar constellation of Cepheus. It is faintly visible to the naked eye with a combined apparent visual magnitude of 4.77.[2] The system is located at a distance of approximately 319 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −32 km/s.[1] It is predicted to come to within 188.7 light-years in around 1.876 million years.[2] The system has an absolute magnitude of −0.14.[2]

HD 216446
Observation data
Epoch J2000      Equinox J2000
Constellation Cepheus
Right ascension  22h 47m 29.06123s[1]
Declination +83° 09′ 13.7788″[1]
Apparent magnitude (V) 4.77[2] (4.92 + 9.60)[3]
Characteristics
Spectral type K3III[4]
B−V color index 1.257±0.008[2]
Astrometry
Radial velocity (Rv)−32.03±0.15[1] km/s
Proper motion (μ) RA: +24.943±0.415[1] mas/yr
Dec.: +47.532±0.322[1] mas/yr
Parallax (π)10.2152 ± 0.1815[1] mas
Distance319 ± 6 ly
(98 ± 2 pc)
Absolute magnitude (MV)−0.14[2]
Details
A
Radius25.2+0.3
−2.4[1] R☉
Luminosity193±4[1] L☉
Surface gravity (log g)2.21[5] cgs
Temperature4,288+221
−28[1] K
Metallicity [Fe/H]−0.10±0.06[2] dex
Rotational velocity (v sin i)1.0[6] km/s
Other designations
BD+82°703, HD 216446, HIP 112519, HR 8702, SAO 3794, WDS J22475+8309[7]
Database references
SIMBADdata

The magnitude 4.92[3] primary, designated component A, is an aging giant star with a stellar classification of K3III.[4] The luminosity class of III typically indicates that the star has exhausted the supply of hydrogen at its core, then cooled and expanded off the main sequence. At present it has 25[1] times the radius of the Sun. The star has a lower abundance of elements other than hydrogen and helium compared to the Sun; what astronomers term the star's metallicity. It is radiating 193 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4288 K.[1]

The secondary companion, component B, is a magnitude 9.60 star located at an angular separation of 3.50″ from the primary, along a position angle of 38°, as of 1992.[3]

References
  1. 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.
  2. 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.
  3. Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122: 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  4. Abt, H. A. (September 1985). "Visual multiples. VIII - 1000 MK types". Astrophysical Journal Supplement Series. 59: 95–112. Bibcode:1985ApJS...59...95A. doi:10.1086/191064.
  5. McWilliam, Andrew (1990), "High-Resolution Spectroscopic Survey of 671 GK Giants. I. Stellar Atmosphere Parameters and Abundances", The Astrophysical Journal Supplement Series, 74: 1075, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527
  6. De Medeiros, J. R.; Mayor, M. (1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement Series. 139 (3): 433. arXiv:astro-ph/0608248. Bibcode:1999A&AS..139..433D. doi:10.1051/aas:1999401.
  7. "HD 216446". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-08-01.
  8. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
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