Pi Piscium
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Pisces |
| Right ascension | 01h 37m 05.91523s[1] |
| Declination | +12° 08′ 29.5186″[1] |
| Apparent magnitude (V) | 5.60[2] (5.56 + 9.56)[3] |
| Characteristics | |
| Spectral type | F0 V[4] + KV[3] |
| Astrometry | |
| Radial velocity (Rv) | −1.0[2] km/s |
| Proper motion (μ) | RA: −77.29[1] mas/yr Dec.: +9.13[1] mas/yr |
| Parallax (π) | 28.50±0.97 mas[1] |
| Distance | 114 ± 4 ly (35 ± 1 pc) |
| Absolute magnitude (MV) | +2.94[2] |
| Details[3] | |
| A | |
| Mass | 1.42 M☉ |
| Radius | 1.68[a] R☉ |
| Luminosity | 5.45[b] L☉ |
| Surface gravity (log g) | 4.16 cgs |
| Temperature | 6,810 K |
| Metallicity [Fe/H] | −0.10 dex |
| Rotational velocity (v sin i) | 105.9[2] km/s |
| Age | 2.0[5] Gyr |
| B | |
| Mass | 0.75 M☉ |
| Radius | 0.69[a] R☉ |
| Luminosity | 0.207[b] L☉ |
| Temperature | 4,700 K |
| Other designations | |
| Idigna, π Psc, 102 Piscium, BD+11°205, FK5 1046, GC 1954, HD 9919, HIP 7535, HR 463, SAO 92536, PPM 117498[6] | |
| Database references | |
| SIMBAD | data |
Pi Piscium, also named Idigna,[7] is a spectroscopic binary[3] star in the zodiac constellation of Pisces. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.60.[2] Based upon an annual parallax shift of 28.50 mas as seen from Earth,[1] it is 114 light years distant. It is a member of the thin disk population of the Milky Way.[8]
Naming
[edit]Pi Piscium (Latinized from π Piscium, abbreviated Pi Psc, π Psc) is the star's Bayer designation. In Chinese astronomy, 右更 (Yòu Gèng), meaning Official in Charge of the Pasturing, refers to an asterism consisting of π Piscium, η Piscium, ρ Piscium, ο Piscium and 104 Piscium. Consequently, the Chinese name for π Piscium itself is 右更三 (Yòu Gèng sān, English: the Third Star of Official in Charge of the Pasturing.)[9]
This star system was part of the Sumerian constellation IDIGNA, representing the river Tigris. In ancient Mesopotamia, Pisces was visualized both as a swallow (SIM.MAḪ) and as the Tigris and Euphrates rivers.[10] The IAU Working Group on Star Names adopted the name Idigna for Pi Piscium A on 17 September 2026.[7][c]
Properties
[edit]The primary, of apparent magnitude 5.56,[3] is an ordinary F-type main-sequence star with a stellar classification of F0 V.[4] At the estimated age of two billion years,[5] it is about 55% of the way through its main sequence lifetime[12] and still has a relatively high rate of spin with a projected rotational velocity of 105.9 km/s.[2] The star has 1.42 times the mass of the Sun and 1.68[a] of the Sun's radius. It is radiating 5.5[b] times the Sun's luminosity at an effective temperature of 6,810 K.[3] At that temperature, Pi Piscium A has a yellow-white hue, as many F-type stars.[13]
The secondary, of apparent magnitude 9.56, is a K-dwarf star. It is 0.75 times as massive than the Sun, 0.69[a] times as large, and has 21%[b] of the luminosity. Its effective temperature is 4,700 K,[3] giving it an orange hue typical of K-type stars.[13]
Analysis of its motion suggests Pi Piscium may be a member of the Ursa Major association, but higher-quality observations are needed to confirm this.[3]
Notes
[edit]- 1 2 3 4 Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:
- 1 2 3 4 Calculated from the equation L = 100.4 • (4.74 − Mbol, where Mbol is the absolute bolometric magnitude. For component A, a value of 2.90 is used, while for B a value of 6.45 is used.
- ↑ The name Idigna was originally adopted for the fainter variable star HD 10783 (UZ Piscium), but changed to π Piscium shortly afterward.[11]
References
[edit]- 1 2 3 4 5 6 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- 1 2 3 4 5 6 Paunzen, E.; et al. (July 2014), "Investigating the possible connection between λ Bootis stars and intermediate Population II type stars", Astronomy & Astrophysics, 567: 8, arXiv:1406.3936, Bibcode:2014A&A...567A..67P, doi:10.1051/0004-6361/201423817, S2CID 56332289, A67.
- 1 2 3 4 5 6 7 8 Fuhrmann, Klaus; Chini, Rolf (January 2019), "On the Secondary of π Piscium", Research Notes of the AAS, 3 (1): 10, Bibcode:2019RNAAS...3...10F, doi:10.3847/2515-5172/aafd39, ISSN 2515-5172.
- 1 2 Cowley, Anne; Fraquelli, Dorothy (February 1974), "MK Spectral Types for Some Bright F Stars", Publications of the Astronomical Society of the Pacific, 86 (509): 70, Bibcode:1974PASP...86...70C, doi:10.1086/129562.
- 1 2 Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
- ↑ "pi. Psc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-25.
{{cite web}}: CS1 maint: postscript (link) - 1 2 "IAU Catalog of Star Names". Retrieved 21 September 2026.
- ↑ Ramírez, I.; et al. (September 2012), "Lithium Abundances in nearby FGK Dwarf and Subgiant Stars: Internal Destruction, Galactic Chemical Evolution, and Exoplanets", The Astrophysical Journal, 756 (1): 46, arXiv:1207.0499, Bibcode:2012ApJ...756...46R, doi:10.1088/0004-637X/756/1/46, S2CID 119199829.
- ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日 Archived 2016-03-03 at the Wayback Machine
- ↑ Hoffmann, Susanne M. "Idigna". All Skies Encyclopaedia. IAU Working Group on Star Names. Retrieved 21 September 2026.
- ↑ ASE edit history
- ↑ Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
- 1 2 "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2013-12-03, retrieved 2012-01-16
