SZ Piscium

SZ Piscium

A visual band light curve for SZ Piscium, adapted from Eaton et al. (1982)[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pisces
Right ascension 23h 13m 23.778s[2]
Declination 02° 40′ 31.60″[2]
Apparent magnitude (V) 7.18[3]
Characteristics
Spectral type K1IV + F8V + ?[4]
Variable type EA/DS/RS[3]
Astrometry
Radial velocity (Rv)12.00±2[5] km/s
Proper motion (μ) RA: 23.624 mas/yr[2]
Dec.: 26.346 mas/yr[2]
Parallax (π)10.6705 ± 0.1864 mas[2]
Distance306 ± 5 ly
(94 ± 2 pc)
Orbit[4]
PrimaryK star
CompanionF star
Period (P)3.96566356 d
Semi-major axis (a)15.2 R☉[6]
Eccentricity (e)0 (fixed)
Inclination (i)69.75°
Semi-amplitude (K1)
(primary)		74.2 km/s
Semi-amplitude (K2)
(secondary)		103.98 km/s
Details
K star
Mass1.74[6] M☉
Radius6.0[6] R☉
Luminosity12.3[6] L☉
Temperature4,910[4] K
Rotational velocity (v sin i)3.0±0.6[4] km/s
F star
Mass1.33[6] M☉
Radius1.52[6] R☉
Luminosity3.98[6] L☉
Temperature6,090[4] K
Rotational velocity (v sin i)67.7±1.0[4] km/s
Other designations
SZ Psc, AG+02 2918, BD+01 4695, HD 219113, HIP 114639, SAO 128041, PPM 173881, WDS 23134+0241[7]
Database references
SIMBADdata

SZ Piscium is a suspected triple star[4] system in the equatorial constellation of Pisces. The inner pair form a double-lined spectroscopic binary with an orbital period of 3.966 days.[8] It is a detached Algol-type eclipsing binary of the RS Canum Venaticorum class with a subgiant component. (This means the pair have a close but separated orbit with the stars eclipsing one another, and the primary component is an evolving star showing star spots and other magnetic activity.) The system is too faint to be readily visible to the naked eye with a combined apparent visual magnitude of 7.18.[3] It is located at a distance of approximately 306 light years based on parallax measurements.[2]

The variability of this star was reported by A. Jensch in 1934, who published the first elements.[9] In 1956 the spectrum of the system was examined by N. G. Roman, who found the cooler component is the brighter and more evolved.[10] The system was studied by G. A. Bakos and J. F. Heard in 1958, who found a magnitude of 7.72 for the primary eclipse minimum and 7.30 for the secondary. They refined the class estimates, finding the primary is probably a K1IV subgiant in close orbit with an F8V main sequence star.[11] In 1972, H. L. Atkins and D. S. Hall included it on a list of RS Canum Venaticorum type variable systems and showed it has an infrared excess.[12]

S. Jakate and associates in 1976 found that the period of luminosity variation is changing over time. They discovered strong emission in the H and K lines of the K star and noted that it showed intrinsic variability.[8] The system displayed unusual episodes of emission and variation in the Hα line, which was interpreted by astronomers as ejected material possibly forming a transient disk.[13] The orbital period of the system varies in a 56 year cycle with an amplitude of 4.3×10−4 d, which may be explained by influences of the stellar wind and magnetic activity.[4]

Significant star spot activity was found all over the K-type star, with variations in the total spot coverage observed over time.[6] It is estimated to be filling 85% of its Roche lobe due to the gravitational influence of the secondary. The rotation period of this star is several times slower than its orbital period, while the rotation of the F-type star is synchronous.[4] Changes in radial velocity of the system over time suggest it is a triple star system,[6] with the tertiary component having ~90% of the mass of the Sun and an orbital period of 1,283±10 days.[4]

  1. ^ Cite error: The named reference Eaton was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i j Cite error: The named reference Xiang_et_al_2016 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Karatas_et_al_2004 was invoked but never defined (see the help page).
  6. ^ a b c d e f g h i Cite error: The named reference Eaton_Henry_2007 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Jakate_et_al_1976 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Kang_et_al_2003 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Roman1956 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Bakos_Heard_1958 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Atkins_Hall_1972 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Ramsey_Nations_1981 was invoked but never defined (see the help page).