2 Ceti

2 Ceti is a single^[12] star in the equatorial constellation of Cetus, near the border with Aquarius. It is visible to the naked eye with an apparent visual magnitude of 4.483.^[2] The distance to 2 Ceti can be estimated from its annual parallax shift of 12.0 mas,^[1] which yields a value of around 272 light years. It appears to be moving further from the Earth with a heliocentric radial velocity of about +8 km/s.^[6]

2 Ceti

Observation data Epoch J2000      Equinox J2000
Constellation	Cetus
Right ascension	00h 03m 44.38784s[1]
Declination	−17° 20′ 09.5719″[1]
Apparent magnitude (V)	4.483[2]
Characteristics
Spectral type	B9 IVn[3]
U−B color index	−0.12[4]
B−V color index	−0.047±0.003[5]
Astrometry
Radial velocity (Rv)	+8.0±4.6[6] km/s
Proper motion (μ)	RA: +25.17[1] mas/yr Dec.: −9.16[1] mas/yr
Parallax (π)	11.98 ± 0.26 mas[1]
Distance	272 ± 6 ly (83 ± 2 pc)
Absolute magnitude (MV)	−0.06[5]
Details
Mass	2.68±0.11[7] M☉
Radius	2.75[7] R☉
Luminosity	119+6 −5[8] L☉
Surface gravity (log g)	3.99±0.09[7] cgs
Temperature	11,419±388[9] K
Metallicity [Fe/H]	+0.00±0.24[3] dex
Rotational velocity (v sin i)	116[8] or 237[10] km/s
Age	217[9] Myr
Other designations
2 Cet, BD−18° 6417, FK5 905, HD 225132, HIP 301, HR 9098, SAO 147059[11]
Database references
SIMBAD	data

The stellar classification for this star is B9 IVn,^[3] matching a B-type subgiant star with "nebulous" absorption lines due to rapid rotation.^[13] Estimates of the rotation rate range from 116^[8] to 237^[10] km/s, and this high rate of spin is giving the star an equatorial bulge that is 12% larger than the polar radius.^[13] 2 Ceti is about 217^[9] million years old with 2.7^[7] times the mass of the Sun and 2.75^[7] times the Sun's radius. It is radiating 119^[8] times the Sun's luminosity from its photosphere at an effective temperature of 11,419 K.^[9] An infrared excess has been detected around this star by the Akari satellite at a wavelength of 18μm, suggesting there is an orbiting debris disk.^[14]

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. Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
3. Wu, Yue; et al. (2010). "Coudé-feed stellar spectral library – atmospheric parameters". Astronomy & Astrophysics. 525: A71. arXiv:1009.1491. Bibcode:2011A&A...525A..71W. doi:10.1051/0004-6361/201015014. S2CID 53480665.
4. Nicolet, B. (1964). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics Supplement Series. 34: 1–49. Bibcode:1978A&AS...34....1N.
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. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
7. Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A.
8. Zorec, J.; et al. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789.
9. 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.
10. Royer, F.; et al. (2007). "Rotational velocities of A-type stars". Astronomy and Astrophysics. 463 (2): 671. arXiv:astro-ph/0610785. Bibcode:2007A&A...463..671R. doi:10.1051/0004-6361:20065224. S2CID 18475298.
11. "2 Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved December 23, 2018.
12. Chini, R.; et al. (2012). "A spectroscopic survey on the multiplicity of high-mass stars". Monthly Notices of the Royal Astronomical Society. 424 (3): 1925–1929. arXiv:1205.5238. Bibcode:2012MNRAS.424.1925C. doi:10.1111/j.1365-2966.2012.21317.x. S2CID 119120749.
13. van Belle, Gerard T. (March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20 (1): 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2. S2CID 119273474.
14. Ishihara, Daisuke; et al. (May 2017). "Faint warm debris disks around nearby bright stars explored by AKARI and IRSF". Astronomy & Astrophysics. 601: 18. arXiv:1608.04480. Bibcode:2017A&A...601A..72I. doi:10.1051/0004-6361/201526215. S2CID 55234482. A72.