Kappa1 Ceti

Kappa1 Ceti, Latinized from κ1 Ceti, is a variable yellow dwarf star approximately 30 light-years away[1] in the equatorial constellation of Cetus.

For other stars with this Bayer designation, see κ Ceti.
κ1 Ceti
Location of κ1 Ceti (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cetus
Right ascension 03h 19m 21.6960s[1]
Declination +03° 22′ 12.712″[1]
Apparent magnitude (V) 4.84[2]
Characteristics
Spectral type G5Vv[3]
U−B color index +0.185[4]
B−V color index +0.674[4]
Variable type BY Dra[5]
Astrometry
Radial velocity (Rv)+19.9[6] km/s
Proper motion (μ) RA: 269.30±0.24[1] mas/yr
Dec.: 93.75±0.22[1] mas/yr
Parallax (π)109.41 ± 0.27 mas[1]
Distance29.81 ± 0.07 ly
(9.14 ± 0.02 pc)
Absolute magnitude (MV)5.16[7]
Details
Mass1.037±0.042[2] M☉
Radius0.95±0.10[8] R☉
Luminosity0.85[9] L☉
Surface gravity (log g)4.51[10] cgs
Temperature5,708[10] K
Metallicity [Fe/H]+0.05[10] dex
Rotation9.2 days[9]
Rotational velocity (v sin i)4.5[9] km/s
Age300–400[11] Myr
Other designations
κ1 Cet, 96 Ceti, NSV 1100, BD+02°518, FK5 1095, GJ 137, HD 20630, HIP 15457, HR 996, SAO 111120, LTT 11094
Database references
SIMBADdata
ARICNSdata

The star was discovered to have a rapid rotation, roughly once every nine days. Though there are no extrasolar planets confirmed to be orbiting the star, Kappa1 Ceti is considered a good candidate to contain terrestrial planets, like the Earth. The system is a candidate binary star, but has not been confirmed.[12]

Description
A light curve for Kappa1 Ceti, plotted from Hipparcos data[13]

Kappa1 Ceti is a yellow dwarf star of the spectral type G5Vv.[3] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[14] The star has roughly the same mass as the Sun, with 95% of the Sun's radius[8] but only 85 percent of the luminosity.[9] Its brightness varies by a few hundredths of a magnitude over a period of nine days and it is classified as a BY Draconis variable, a type of variable star where the brightness changes are due to spots on its surface as it rotates.[5]

The rapid rotation rate of this star, approximately once every nine days, is indicative of a relatively youthful body several hundred million years in age. Due to starspots, the star varies slightly over approximately the same period. The variations in the period are thought to be caused by differential rotation at various latitudes, similar to what happens on the surface of the Sun. The starspots on Kappa1 Ceti range in latitude from 10° to 75°[9] The magnetic properties of this star make it "an excellent match for the Sun at a key point in the Earth's past".[15]

According to recent hypotheses, unusually intense stellar flares from a solar twin star could be caused by the interaction of the magnetic field of a giant planet in a tight orbit with that star's own magnetic field.[16] Some Sun-like stars of spectral class F8 to G8 have been found to undergo enormous magnetic outbursts to produce so-called superflares (coronal mass ejections) that release between 100 and 10 million times more energy than the largest flares ever observed on the sun, making them brighten briefly by up to 20 times.[16]

Magnetic field measurements for κ1 Cet were reported in 2016.[17] These authors used spectropolarimetric observations from NARVAL to reconstruct the magnetic field topology and to quantitatively investigate the interactions between the stellar wind and a possible surrounding planetary system. A magnetic field detection was reported for κ1 Cet[17]., with an average field strength of 24 G, and a maximum value of 61 G. Stellar wind model [17] shows a mass-loss rate of 9.7×10−13 M☉·yr−1, i.e., 50 times larger than the current solar wind mass-loss rate.[17] Recent data constrained model of the star suggests that its mass loss rate is as high as 100 times of the solar mass-loss rate.[18]

The space velocity components of this star are (U, V, W) = (−22.41, −4.27, −5.32) km/s.[3] It is not known to be a member of a moving group of stars.[9]

See also

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. Vizier catalog entry
  2. Boyajian, Tabetha S.; et al. (February 2012). "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars". The Astrophysical Journal. 746 (1): 101. arXiv:1112.3316. Bibcode:2012ApJ...746..101B. doi:10.1088/0004-637X/746/1/101. S2CID 18993744.
  3. Montes, D.; et al. (November 2001). "Late-type members of young stellar kinematic groups - I. Single stars". Monthly Notices of the Royal Astronomical Society. 328 (1): 45–63. arXiv:astro-ph/0106537. Bibcode:2001MNRAS.328...45M. doi:10.1046/j.1365-8711.2001.04781.x. S2CID 55727428.
  4. Cousins, A. W. J. (1984). "Standardization of Broadband Photometry of Equatorial Standards". Circulars of the South African Astronomical Observatory. 8: 59. Bibcode:1984SAAOC...8...59C.
  5. Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
  6. Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.
  7. Elgarøy, Øystein; Engvold, Oddbjørn; Lund, Niels (March 1999). "The Wilson-Bappu effect of the MgII K line - dependence on stellar temperature, activity and metallicity". Astronomy and Astrophysics. 343: 222–228. Bibcode:1999A&A...343..222E.
  8. Walker, Gordon A. H.; et al. (April 2007). "The Differential Rotation of κ1 Ceti as Observed by MOST". The Astrophysical Journal. 659 (2): 1611–1622. arXiv:0704.2204. Bibcode:2007ApJ...659.1611W. doi:10.1086/511851. S2CID 15937336.
  9. Gaidos, E. J.; Henry, G. W.; Henry, S. M. (2000). "Spectroscopy and Photometry of Nearby Young Solar Analogs". The Astronomical Journal. 120 (2): 1006–1013. Bibcode:2000AJ....120.1006G. CiteSeerX 10.1.1.43.4478. doi:10.1086/301488. S2CID 16930014.
  10. Soubiran, C.; Bienaymé, O.; Mishenina, T. V.; Kovtyukh, V. V. (March 2008). "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants". Astronomy and Astrophysics. 480 (1): 91–101. arXiv:0712.1370. Bibcode:2008A&A...480...91S. doi:10.1051/0004-6361:20078788. S2CID 16602121.
  11. Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. S2CID 27151456.
  12. Hartkopf, W. I.; McAlister, H. A. (January 1984). "Binary stars unresolved by speckle interferometry. III". Astronomical Society of the Pacific. 96: 105–116. Bibcode:1984PASP...96..105H. doi:10.1086/131309.
  13. "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
  14. Garrison, R. F. (December 1993). "Anchor Points for the MK System of Spectral Classification". Bulletin of the American Astronomical Society. 25: 1319. Bibcode:1993AAS...183.1710G. Archived from the original on 2019-06-25. Retrieved 2012-02-04.
  15. Ribas, Ignasi (August 2009). "The Sun and stars as the primary energy input in planetary atmospheres". Proceedings of the International Astronomical Union: Solar and Stellar Variability: Impact on Earth and Planets. Vol. 264. pp. 3–18. arXiv:0911.4872. Bibcode:2010IAUS..264....3R. doi:10.1017/S1743921309992298.
  16. Schaefer, Bradley E.; King, Jeremy R.; Deliyannis, Constantine P. (2000). "Superflares on Ordinary Solar-Type Stars". The Astrophysical Journal. 529 (2): 1026–1030. arXiv:astro-ph/9909188. Bibcode:2000ApJ...529.1026S. doi:10.1086/308325. S2CID 10586370.
  17. J.-D. do Nascimento, Jr, F. (2016). "Magnetic Field and Wind of Kappa Ceti: Toward the Planetary Habitability of the Young Sun when Life Arose on Earth". The Astrophysical Journal Letters. 820 (1): 15–20. arXiv:1603.03937. Bibcode:2016ApJ...820L..15D. doi:10.3847/2041-8205/820/1/L15. S2CID 118483378.
  18. V. S. Airapetian, F. (2021). "One Year in the Life of Young Suns: Data-constrained Corona-wind Model of κ1 Ceti". The Astrophysical Journal. 916 (2): 96–110. arXiv:1603.03937. Bibcode:2016ApJ...820L..15D. doi:10.3847/1538-4357/ac081e. S2CID 235294099.


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