Zeta Cygni

Zeta Cygni
Location of ζ Cygni (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cygnus
Right ascension 21h 12m 56.18594s[1]
Declination +30° 13′ 36.8957″[1]
Apparent magnitude (V) 3.26[2]
Characteristics
Spectral type G8IIIa + DA4.2[3]
U−B color index +0.77[2]
B−V color index +0.98[2]
Astrometry
Radial velocity (Rv)+15.85 ± 0.26[4] km/s
Proper motion (μ) RA: +6.51[1] mas/yr
Dec.: –68.21[1] mas/yr
Parallax (π)21.8130 ± 0.1375 mas[5]
Distance149.5 ± 0.9 ly
(45.8 ± 0.3 pc)
Absolute magnitude (MV)–0.01[6]
Orbit[7]
Period (P)6,489 ± 31 days
Semi-major axis (a)0.19"[8]
Eccentricity (e)0.22 ± 0.03
Periastron epoch (T)40,712 ± 178 MJD
Argument of periastron (ω)
(secondary)		41 ± 10°
Semi-amplitude (K1)
(primary)		3.31 ± 0.12 km/s
Details
ζ Cyg A
Mass3.05[9] M☉
Radius15[4] R☉
Luminosity112[4] L☉
Surface gravity (log g)2.41[6] cgs
Temperature4,910[6] K
Metallicity [Fe/H]–0.04[6] dex
Rotational velocity (v sin i)0.4 ± 0.5[9] km/s
Age0.2[10] Gyr
ζ Cyg B
Mass0.6[8] M☉
Temperature12,000[8] K
Other designations
Zeta Cyg, 64 Cygni, BD+29°4348, HD 202109, HIP 104732, HR 8115, SAO 71070[11]
Database references
SIMBADdata

Zeta Cygni (ζ Cyg) is a binary star system in the northern constellation of Cygnus, the swan. It has an apparent visual magnitude of 3.26 and, based upon parallax measurements, is about 143 light-years (44 parsecs) away.

The primary component, ζ Cyg A is a giant star with a spectral type of G8 IIIp. Its most likely status is as a red clump giant, an evolved star that has begun core helium fusion. It has around three times the mass of the Sun and has expanded to about 15 times the Sun's radius. It is radiating 112 times the brightness of the Sun from its outer atmosphere at an effective temperature of 4,910 K. At this temperature, the star glows with the yellow hue of a G-type star.[12]

The secondary component, ζ Cyg B, is a white dwarf of type DA4.2. The pair orbit each other every 6,489 days (17.8 years) with an eccentricity of 0.22. The white dwarf cannot be seen directly, but is estimated to have an apparent magnitude of 13.2.[3]

Zeta Cygni has an overabundance of barium, as well as other heavy chemical elements in its atmosphere, making it a so-called "mild" barium star. These elements were synthesized by the other member of the system as it passed through the asymptotic giant branch (AGB) stage of its evolution, then ejected in its stellar wind and accreted onto the current primary component. Prior to acquiring this additional mass, Zeta Cygni had about 2.5 times the mass of the Sun, while the more evolved AGB star had three solar masses.[9]

  1. ^ a b c d Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference apjss52_7 was invoked but never defined (see the help page).
  3. ^ a b Holberg, J. B.; Oswalt, T. D.; Sion, E. M.; Barstow, M. A.; Burleigh, M. R. (2013). "Where are all the Sirius-like binary systems?". Monthly Notices of the Royal Astronomical Society. 435 (3): 2077. arXiv:1307.8047. Bibcode:2013MNRAS.435.2077H. doi:10.1093/mnras/stt1433. S2CID 54551449.
  4. ^ a b c Cite error: The named reference aj135_1_209 was invoked but never defined (see the help page).
  5. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  6. ^ a b c d Cite error: The named reference aaa525_A63 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference obs112_168 was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference mnras322_4_891 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference aaa413_1105 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference aaa468_2_679 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).