UV Piscium

UV Piscium

A light curve for UV Piscium plotted from TESS data[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Pisces
Right ascension 01h 16m 55.119s[2]
Declination +06° 48′ 42.13″[2]
Apparent magnitude (V) 8.98[3]
Characteristics
Primary
Evolutionary stage Main sequence
Spectral type G5V[4]
B−V color index 0.65±0.02[4]
Variable type Detached Algol + RS CVn[5]
Secondary
Evolutionary stage Main sequence
Spectral type K3V[4]
B−V color index 1.04±0.07[4]
Astrometry
Radial velocity (Rv)6.45±0.40[6] km/s
Proper motion (μ) RA: +85.250 mas/yr[2]
Dec.: +20.946 mas/yr[2]
Parallax (π)14.0593 ± 0.0236 mas[2]
Distance232.0 ± 0.4 ly
(71.1 ± 0.1 pc)
Absolute magnitude (MV)4.48±0.05[4]
Orbit[7]
Period (P)0.86104716 d
Eccentricity (e)0.0 (assumed)
Inclination (i)88.9±2.0[4]°
Periastron epoch (T)2,448,897.4226±0.0003 HJD
Semi-amplitude (K1)
(primary)		117.20±0.18 km/s
Semi-amplitude (K2)
(secondary)		154.81±0.37 km/s
Details[7]
Primary
Mass1.0225±0.0058 M☉
Radius1.096 R☉
Surface gravity (log g)4.340±0.018 cgs
Temperature5,780±100 K
Metallicity [Fe/H]0.025±0.066[8] dex
Rotation0.86 d
Rotational velocity (v sin i)71.01+0.37
−0.36 km/s
Age4.7 Gyr
Secondary
Mass0.7741±0.0034 M☉
Radius0.829 R☉
Surface gravity (log g)4.478±0.019 cgs
Temperature4,750±80 K
Rotation0.86 d
Rotational velocity (v sin i)51.66+1.25
−1.20 km/s
Other designations
UV Psc, BD+06°189, HD 7700, HIP 5980, SAO 109778[9]
Database references
SIMBADdata

UV Piscium is a binary star system in the constellation of Pisces. With a peak apparent visual magnitude of 8.98,[3] it is too faint to be visible to the naked eye. This is an eclipsing binary system that decreases to magnitude 10.05 during the primary eclipse, then to magnitude 9.54 with the secondary eclipse. It is located at a distance of 232 light years from the Sun based on parallax measurements,[2] and is receding with a radial velocity of 6.5 km/s.[6] The position of this star near the ecliptic means it is subject to lunar occultation.[10]

This star was found to be variable by H. Huth in 1959.[11] He determined it to be an eclipsing binary and published the first light curve with a period of 20.67 hours. R. B. Carr in 1969 proposed this to be an Algol-type variable with a minor tidal distortion of the components, plus a large, anomalous asymmetry in the light curve.[12] D. S. Hall in 1976 grouped it among the class of short-period RS CVn binaries.[13] The following year, variable, non-thermal radio emission was detected coming from this system, the first such discovered for a short-period binary.[14]

Daniel M. Popper in 1969 found a double-lined, G-type spectrum with both components showing emission in the H and K lines.[15] In 1979, A. R. Sadik deduced the system is a detached binary and suggested a bright, hot spot may produce the observed asymmetry in the light curve. He found stellar classifications of G2V and K0IV for the primary and secondary components, respectively.[12] With improved spectra, Popper found main sequence classes of G5 and K3 for the two stars.[4] The presence of a prominence was deduced in 1992, and a flare of hydrogen alpha was observed the following year.[16]

This is a close binary system with an orbital period of 0.86 days. The orbit is circular and the components are spinning rapidly in-sync with their orbital period. This rotation rate is making both stars magnetically active, with average magnetic field strengths of 137 G and 88 G for the primary and secondary, respectively. Magnetic activity cycles appear to be causing the orbital period to oscillate with a 61 year period.[17] The primary is a G-type main-sequence star of about the same size and mass as the Sun, while the secondary is a smaller K-type main-sequence star. They are estimated to be about 4.6 billion years old.[7]

  1. ^ Cite error: The named reference MAST 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 Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  4. ^ a b c d e f g Cite error: The named reference Popper1997 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Karataș_et_al_2004 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Hahlin_et_al_2021 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Qian_et_al_2018 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Herr1969 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Huth1959 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference Sadik_1979 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Hall_1976 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Spangler_et_al_1977 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Popper1969 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Liu_et_al_1996 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Qian_et_al_1999 was invoked but never defined (see the help page).