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Star in the constellation Piscis Austrinus From Wikipedia, the free encyclopedia
Pi Piscis Austrini, Latinized from π Piscis Austrini, is binary star[5] system in the southern constellation of Piscis Austrinus, near the eastern constellation border with Sculptor. It has a yellow-white hue and is visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.12.[2] The system is located at a distance of 92 light-years from the Sun based on parallax.[1] Its radial velocity is poorly constrained, but it appears to be drifting closer at a rate of around −6 km/s.[2] Pi Piscis Austrini is moving through the galaxy at a velocity of 16.3 km/s relative to the Sun. Its projected galactic orbit carries it between 24,000 and 37,500 light-years from the center of the galaxy.[2]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Piscis Austrinus |
Right ascension | 23h 03m 29.81653s[1] |
Declination | −34° 44′ 57.8827″[1] |
Apparent magnitude (V) | 5.12[2] |
Characteristics | |
Spectral type | F1 V Fe-0.8[3] + F3 V[4][5] |
U−B color index | +0.00[6] |
B−V color index | +0.29[6] |
Astrometry | |
Radial velocity (Rv) | −6.0±4.2[2] km/s |
Proper motion (μ) | RA: +72.789[1] mas/yr Dec.: +83.569[1] mas/yr |
Parallax (π) | 35.3691 ± 0.2124 mas[1] |
Distance | 92.2 ± 0.6 ly (28.3 ± 0.2 pc) |
Absolute magnitude (MV) | +2.78[2] |
Orbit[7] | |
Period (P) | 178.3177±0.0038 d |
Semi-major axis (a) | ≥ 0.296 AU |
Eccentricity (e) | 0.5286±0.0041 |
Periastron epoch (T) | 2,435,319.73±0.25 |
Argument of periastron (ω) (secondary) | 2.62±0.81° |
Semi-amplitude (K1) (primary) | 21.28±0.16 km/s |
Details | |
A | |
Mass | 1.51[3] M☉ |
Radius | 1.64+0.11 −0.08[1] R☉ |
Luminosity | 5.85±0.04[1] L☉ |
Surface gravity (log g) | 4.30±0.14[3] cgs |
Temperature | 7,003+195 −216[1] K |
Metallicity [Fe/H] | +0.12[2] dex |
Age | 474[3] Myr |
Other designations | |
Database references | |
SIMBAD | data |
This is a single-lined spectroscopic binary system with an orbital period of 178.3 days and an eccentricity of 0.53.[7] The primary component is an F-type main-sequence star with a stellar classification of F1 V Fe-0.8.[3]
As of 2023, there appears to be no consensus in the astronomical literature about whether or not Pi Piscis Austrini is a variable star, and if it is variable, what type of variable star it is. In 1965 it was designated a classical Cepheid variable star with a visual (V) band brightness that varied by 0.3 magnitudes over a period of 7.975 days.[10] The AAVSO's International Variable Star index lists it as a Gamma Doradus variable, with a V band magnitude range of 5.10 to 5.12.[11] Axel Thomas, writing in the AAVSO's Journal, reports that the star appears to be a semiregular variable star, varying by 0.7 magnitudes in V band over a period of 8.625 days.[12] Koen and Eyer examined the Hipparcos data for the star, and report it to be a microvariable with a period of 1.06039 days.[13] On the other hand, the General Catalog of Variable Stars reports the star's brightness as constant,[14] and in separate studies Michel Petit[15] and E. Janot-Pacheco could not detect any change in brightness.[10]
Pi Piscis Austrini displays an infrared excess, suggesting a circumstellar disk is orbiting at a radius of 23 AU with a mean temperature of 90 K.[16] The cooler secondary companion has a class of F3 V.[5] The system appears to be a source of X-ray emission.[17]
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