Kappa Piscium

Kappa Piscium

Location of κ Piscium (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Pisces
Right ascension	23^h 26^m 55.95586^s[1]
Declination	+01° 15′ 20.1900″[1]
Apparent magnitude (V)	4.94[2]
Characteristics
Evolutionary stage	Main sequence
Spectral type	A2 Vp SrCrSi[3]
U−B color index	−0.03[2]
B−V color index	+0.04[2]
Variable type	α^2 CVn[4]
Astrometry
Proper motion (μ)	RA: +86.68[1] mas/yr Dec.: −94.29[1] mas/yr
Parallax (π)	21.25 ± 0.29 mas[1]
Distance	153 ± 2 ly (47.1 ± 0.6 pc)
Absolute magnitude (MV)	+1.59[5]
Details
Mass	2.62[6] M☉
Radius	1.71[7] R☉
Luminosity	30[8] L☉
Surface gravity (log g)	4.2[7] cgs
Temperature	9,470[7] K
Metallicity [Fe/H]	+0.74[5] dex
Rotational velocity (v sin i)	38.4±1.5[7] km/s
Age	157[6] Myr
Other designations
κ Psc, 8 Piscium, BD+00° 4998, FK5 884, HD 220825, HIP 115738, HR 8911, SAO 128186, WDS J23269+0115A[9]
Database references
SIMBAD	data

Kappa Piscium (κ Piscium) is a solitary,[10] white-hued star in the zodiac constellation of Pisces. It is visible to the naked eye with an apparent visual magnitude of 4.94,[2] forming the southeastern corner of the "Circlet" asterism in Pisces. Based upon a measured annual parallax shift of 21.25 mas as seen from Earth,[1] it is located about 153 light years distant from the Sun. Appearing as a single point in the sky, it is easily split when viewed with a pair of binoculars, and displays three components. Kappa Piscium has an apparent magnitude of 4.87 at maximum brightness and 4.95 at minimum brightness,[4] while the visual companions have apparent magnitudes of 9.96 and 11.20.[11]

A light curve for Kappa Piscium, plotted from TESS data[12]

This is an A-type main-sequence star with a stellar classification of A2 Vp SrCrSi.[3] The suffix designation indicates it is a "chemically peculiar" Ap star[13] that displays abnormal abundances of silicon, strontium, and chromium. It is an Alpha^2 Canum Venaticorum variable[4] with a weak[13] active magnetic field that causes it to fluctuate by 0.01 to 0.1 in magnitude as it rotates. It shows many lines of uranium, and possibly the rare element holmium in its spectrum. Its uranium and osmium content could have been provided by a nearby supernova.[14] Compared to the Sun, it is deficient in oxygen relative to the magnesium abundance.

This star is a candidate member of the AB Doradus moving group, an association of stars with similar ages that share a common heading through space.[8]

Naming

In Chinese, 雲雨 (Yún Yǔ), meaning Cloud and Rain, refers to an asterism consisting of κ Piscium, 12 Piscium, 21 Piscium and λ Piscium. Consequently, the Chinese name for κ Piscium itself is 雲雨一 (Yún Yǔ yī, English: the First Star of Cloud and Rain.)[15]

References

1. 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.
2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
3. Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182.
4. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
5. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
6. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
7. Romanovskaya, A. M.; Shulyak, D. V.; Ryabchikova, T. A.; Sitnova, T. M. (2021-11-01). "Fundamental parameters of the Ap-stars GO And, 84 UMa, and κ Psc". Astronomy & Astrophysics. 655: A106. arXiv:2111.03371. doi:10.1051/0004-6361/202141740. ISSN 0004-6361.
8. McCarthy, Kyle; White, Russel J. (June 2012), "The Sizes of the Nearest Young Stars", The Astronomical Journal, 143 (6): 14, arXiv:1201.6600, Bibcode:2012AJ....143..134M, doi:10.1088/0004-6256/143/6/134, S2CID 118538522, 134.
9. "kap Psc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-28.
10. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
11. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
12. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
13. Glagolevskij, Yu. V.; et al. (October 2006), "Spectroscopic study of the weak magnetic star HD220825-κPsc", Astrophysics, 49 (4): 497–505, Bibcode:2006Ap.....49..497G, doi:10.1007/s10511-006-0048-5, S2CID 121612463.
14. Jørgensen, Christian K. (March 1, 2005), "Heavy elements synthesized in supernovae and detected in peculiar A-type stars", Noble Gas and High Temperature Chemistry, Structure and Bonding, vol. 73, pp. 199–226, doi:10.1007/3-540-52124-0_4, ISBN 978-3-540-52124-2.
15. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 8 日 Archived 2012-04-15 at the Wayback Machine