Theta Piscis Austrini

Theta Piscis Austrini
Location of θ Piscis Austrini (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Piscis Austrinus
Right ascension 21h 47m 44.14993s[1]
Declination −30° 53′ 53.9027″[1]
Apparent magnitude (V) +5.01[2]
Characteristics
Spectral type A1 V + A1 V[3]
B−V color index +0.04[2]
Astrometry
Radial velocity (Rv)+12.80±1.8[4] km/s
Proper motion (μ) RA: −34.40[1] mas/yr
Dec.: −0.08[1] mas/yr
Parallax (π)10.16 ± 0.40 mas[1]
Distance320 ± 10 ly
(98 ± 4 pc)
Absolute magnitude (MV)+0.06[5]
Orbit[3]
Period (P)19.957±0.050 yr
Semi-major axis (a)0.137±0.004″
Eccentricity (e)0.256±0.030
Inclination (i)103±2°
Longitude of the node (Ω)29.1±2.0°
Periastron epoch (T)2006.00 ± 0.07
Argument of periastron (ω)
(secondary)		199±6°
Details
θ PsA A
Mass2.32±0.33[3] M☉
Luminosity86[5] L☉
Surface gravity (log g)4.05[6] cgs
Temperature9,716±330[6] K
Rotational velocity (v sin i)150[6] km/s
Age281[6] Myr
θ PsA B
Mass2.32±0.33[3] M☉
Other designations
θ PsA, 10 Piscis Austrini, CPD−31° 6596, HD 207155, HIP 107608, HR 8326, SAO 213292, WDS J21477-3054AB[7]
Database references
SIMBADdata

Theta Piscis Austrini, Latinized as θ Piscis Austrini, is a binary star[8] system in the southern constellation of Piscis Austrinus. It is faintly visible to the naked eye with a combined apparent visual magnitude of +5.01.[2] Based upon an annual parallax shift of 10.16 mas as seen from the Earth,[1] the system is located around 320 light years from the Sun. The system is drifting further away with a radial velocity of +13 km/s.[4]

The binary nature of this system was discovered in 1951 by South African astronomer W. S. Finsen. Both components A and B have the same apparent magnitude. They orbit each other with a period of 20 years and an eccentricity of 0.256. The pair are A-type main sequence stars with stellar classifications of A1 V.[3] A magnitude 11.3 visual companion star, labelled component C, is located at an angular separation of 33.2 arc seconds along a position angle of 342°, as of 1999.[9]

Theta Piscis Austrini is moving through the Galaxy at a speed of 21.3 km/s relative to the Sun. Its projected Galactic orbit carries it between 22,629 and 38,431 light-years from the center of the Galaxy. Theta Piscis Austrini came closest to the Sun 2.7 million years ago at a distance of 256 light-years.[5]

  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 Cite error: The named reference Nicolet1978 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Docobo2013 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Kharchenko_et_al_2007 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference David2015 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).