Theta Piscium

Theta Piscium
Location of θ Piscium (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pisces
Right ascension 23h 27m 58.09529s[1]
Declination +6° 22′ 44.3720″[1]
Apparent magnitude (V) 4.27[2]
Characteristics
Spectral type K1 III[2]
U−B color index +1.00
B−V color index +1.062[2]
Astrometry
Radial velocity (Rv)+6.05±0.19[2] km/s
Proper motion (μ) RA: −123.83[1] mas/yr
Dec.: −43.26[1] mas/yr
Parallax (π)21.96 ± 0.25 mas[1]
Distance149 ± 2 ly
(45.5 ± 0.5 pc)
Absolute magnitude (MV)+0.83[2]
Details
Mass1.58[3] M☉
Radius11[4] R☉
Luminosity51.3[4] L☉
Surface gravity (log g)2.70[5] cgs
Temperature4,684±23[3] K
Metallicity [Fe/H]0.06[5] dex
Rotational velocity (v sin i)3.1[4] km/s
Age2.45[3] Myr
Other designations
θ Psc, 10 Piscium, BD+05° 5173, FK5 1614, GC 32647, HD 220954, HIP 115830, HR 8916, SAO 128196, PPM 174110[6]
Database references
SIMBADdata

Theta Piscium, Latinized from θ Piscium, is a single,[7] orange-hued star in the zodiac constellation of Pisces, the fish. The annual parallax shift of this star was measured during the Hipparcos mission as 21.96 mas,[1] which yields a distance estimate of about 149 light years. It is a faint star but visible to the naked eye with an apparent visual magnitude of 4.27.[2] The star is moving away from the Sun with a radial velocity of +6 km/s.[2]

At the estimated age of 2.5 billion years,[3] this is an aging giant star with a stellar classification of K1 III,[2] which means it has exhausted the supply of hydrogen at its core. It is a red clump star, indicating it is on the horizontal branch of its evolution and is generating energy through helium fusion at its core.[5] Theta Piscium has 158%[3] of the Sun's mass and its outer atmosphere has swollen to about 11[4] times the girth of the Sun. It is brighter yet cooler than the Sun, radiating 51.3[4] times the Sun's luminosity from its enlarged photosphere at an effective temperature of about 4,684 K.[3]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e f g h Cite error: The named reference aaa454_3_943 was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference Luck2015 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference Massarotti2008 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Liu2007 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).