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Theta Piscium
Star in the constellation Pisces / From Wikipedia, the free encyclopedia
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]
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] |
Distance | 149 ± 2 ly (45.5 ± 0.5 pc) |
Absolute magnitude (MV) | +0.83[2] |
Details | |
Mass | 1.58[3] M☉ |
Radius | 11[4] R☉ |
Luminosity | 51.3[4] L☉ |
Surface gravity (log g) | 2.70[5] cgs |
Temperature | 4,684±23[3] K |
Metallicity [Fe/H] | 0.06[5] dex |
Rotational velocity (v sin i) | 3.1[4] km/s |
Age | 2.45[3] Myr |
Other designations | |
Database references | |
SIMBAD | data |
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]