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Lambda Persei
	Location of λ Persei (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Perseus
Right ascension	04h 06m 35.04360s
Declination	50° 21′ 04.5500″
Apparent magnitude (V)	4.29
Characteristics
Spectral type	A0IVn
U−B color index	−0.04
B−V color index	+0.02
Astrometry
Radial velocity (Rv)	+6.1±2.0 km/s
Proper motion (μ)	RA: −12.75 mas/yr ; Dec.: −35.60 mas/yr
Parallax (π)	7.73 ± 0.22 mas
Distance	420 ± 10 ly ; (129 ± 4 pc)
Absolute magnitude (MV)	−1.31
Details
Radius	3.1 R☉
Luminosity	348 L☉
Surface gravity (log g)	4.05 cgs
Temperature	10,585 K
Metallicity [Fe/H]	+0.01 dex
Rotational velocity (v sin i)	196 km/s
Age	345 Myr
Other designations
	λ Per, 47 Persei, BD+49°1101, FK5 1113, GC 4924, HD 25642, HIP 19167, HR 1261, SAO 24412
Database references
SIMBAD	data

λ Persei, Latinized as Lambda Persei, is a star in the northern constellation of Perseus. It is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.29.^[2] This object is located approximately 422 light years from the Sun based on parallax,^[1] and is drifting further away with a radial velocity of +6 km/s.^[4]

This object has a stellar classification of A0IVn,^[3] matching an A-type subgiant star with "nebulous" lines due to rapid rotation. It is spinning with a projected rotational velocity of 196 km/s,^[8] which is giving the star an equatorial bulge that is an estimated 16% larger than the polar radius.^[11] Unusually for a star of this type, spectra show weak emission features among the Hydrogen lines, which may be due to plage regions on the surface caused by an implied magnetic field.^[12] The star is 345^[9] million years old and is radiating 348^[5] times the luminosity of the Sun from its photosphere at an effective temperature of 10,585 K.^[7]

In Chinese astronomy, Lambda Persei is called 積水, Pinyin: Jīshuǐ, meaning Stored Water, because this star is marking itself and stand alone in Stored Water asterism, Stomach mansion (see : Chinese constellation).^[13]

References

^ ^a ^b ^c ^d ^e ^f 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
^ ^a ^b ^c ^d Ducati, J. R. (2002). "Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
^ ^a ^b Cowley, A.; et al. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications". Astronomical Journal. 74: 375–406. Bibcode:1969AJ.....74..375C. doi:10.1086/110819.
^ ^a ^b Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institution for Science. Bibcode:1953GCRV..C......0W. LCCN 54001336.
^ ^a ^b ^c 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. Vizier catalog entry
^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (2) (Third ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754
^ ^a ^b ^c ^d 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.
^ ^a ^b Hoffleit, D.; Warren, W. H. (1995). "Bright Star Catalogue". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050 (5th Revised ed.). Bibcode:1995yCat.5050....0H.
^ ^a ^b Gontcharov, G. A. (November 2012). "Spatial distribution and kinematics of OB stars". Astronomy Letters. 38 (11): 694–706. arXiv:1606.09028. Bibcode:2012AstL...38..694G. doi:10.1134/S1063773712110035. S2CID 119108982.
^ "lam Per". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-22.
^ Belle, G. T. (2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20: 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2. S2CID 119273474.
^ Underhill, Anne B. (November 1991). "Lambda Persei: an Unusual B9 IV Star". Publications of the Astronomical Society of the Pacific. 103: 1176. Bibcode:1991PASP..103.1176U. doi:10.1086/132937. S2CID 121711589.
^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日