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Pi Piscis Austrini

Pi Piscis Austrini
Location of π Piscis Austrini (circled)
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]
Distance92.2 ± 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
Mass1.51[3] M☉
Radius1.64+0.11
−0.08[1] R☉
Luminosity5.85±0.04[1] L☉
Surface gravity (log g)4.30±0.14[3] cgs
Temperature7,003+195
−216[1] K
Metallicity [Fe/H]+0.12[2] dex
Age474[3] Myr
Other designations
π PsA, CD−35° 15630, GC 32122, GJ 886.2, (Wo) 9807, HD 217792, HIP 113860, HR 8767, SAO 214275[8]
Database references
SIMBADdata

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]

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]

A light curve for Pi Piscis Austrini, plotted from Hipparcos data[9]

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]

  1. ^ a b c d e f g h i Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f g Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Gray2006 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference UBV was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Bopp1970 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference simbad was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference CDS was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Pacheco1974 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference IVSI was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference ThomasAxel was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference KoenEyer was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference GCVSpiPsA was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference MPetit was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Cotten2016 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Haakonsen2009 was invoked but never defined (see the help page).

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