42 Persei


42 Persei is a binary star system in the northern constellation of Perseus. It has the Bayer designation n Persei, while 42 Persei is the Flamsteed designation. The system is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of 5.11.[5] It is located around 93 parsecs (302 ly) distant from the Sun,[1] but is drifting closer with a radial velocity of −12.4 km/s.[6]

42 Persei
Perseus constellation map.svg
Red circle.svg
Location of 42 Persei (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Perseus
Right ascension 03h 49m 32.68952s[1]
Declination 33° 05′ 28.9603″[1]
Apparent magnitude (V) 5.05 - 5.18[2]
Spectral type A3V[3] + MV[4]
U−B color index +0.11[5]
B−V color index +0.07[5]
Variable type Ellipsoidal[4]
Radial velocity (Rv)−12.40[6] km/s
Proper motion (μ) RA: −28.483[7] mas/yr
Dec.: +6.260[7] mas/yr
Parallax (π)10.8041 ± 0.1504 mas[7]
Distance302 ± 4 ly
(93 ± 1 pc)
Absolute magnitude (MV)0.57[8]
Period (P)1.7653511 ± 0.000002 d
Semi-major axis (a)8.207 R
Eccentricity (e)0.056
Inclination (i)65.3°
Argument of periastron (ω)
Semi-amplitude (K1)
34.34 km/s
42 Per A
Mass2.0[4] M
Radius3.48[4] R
Luminosity59[9] L
Surface gravity (log g)3.78[10] cgs
Temperature8,892[9] K
Metallicity [Fe/H]0.00[11] dex
Rotational velocity (v sin i)91[9] km/s
42 Per B
Mass0.38[4] M
Temperature3,500[4] K
Other designations
n Per, 42 Per, V467 Per, BD+32°667, GC 4592, HD 23848, HIP 17886, HR 1177, SAO 56727
Database references
A light curve for V467 Persei, plotted from TESS data[12]

42 Persei is a single-lined spectroscopic binary with an orbital period of 1.77 days and an eccentricity of just 0.056.[4] It is a variable star, ranging in brightness from magnitude 5.05 to 5.18, and was assumed at discovery to be a close, but detached, eclipsing variable.[2] Closer studies of the light variations and the orbit have shown that the main brightness changes are due to rotation of the distorted primary star, although it is predicted from the likely inclination of the orbit that shallow eclipses could also occur.[4]

The visible component is an A-type main-sequence star with a stellar classification of A3V;[3] a star that is fusing its core hydrogen. It has been reported as a mild Am star,[13] but this is considered questionable.[14] The star has twice[4] the mass of the Sun and 3.5[4] times the Sun's radius. It has a high rate of spin, showing a projected rotational velocity of 91 km/s.[9] The star is radiating 59[9] times the luminosity of the Sun from its photosphere at an effective temperature of 8,892 K.[9] The unseen companion star is likely to be a dim red dwarf with 38% of the Sun's mass.[4]

In Chinese astronomy, 42 Persei is called 天讒, Pinyin: Tiānchán, meaning Celestial Slander, because this star is marking itself and stand alone in Celestial Slander asterism, Hairy Head mansion (see : Chinese constellation).[15]


  1. ^ a b c 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. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....1.2025S.
  3. ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  4. ^ a b c d e f g h i j k l Martin, Brian E. (1990). "The ellipsoidal variable 42 Persei - Observations and model". Astronomical Society of the Pacific. 102: 1153–1160. Bibcode:1990PASP..102.1153M. doi:10.1086/132746.
  5. ^ a b c Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  6. ^ a b Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
  7. ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  8. ^ 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
  9. ^ a b c d e f Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789.
  10. ^ 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. Vizier catalog entry
  11. ^ Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. S2CID 118345778.
  12. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  13. ^ Margoni, R.; Munari, U.; Stagni, R. (1992). "Spectroscopic orbits of AM stars. I. Seven field stars". Astronomy and Astrophysics Supplement Series. 93: 545. Bibcode:1992A&AS...93..545M.
  14. ^ Renson, P.; Manfroid, J. (2009). "Catalogue of Ap, HGMN and Am stars". Astronomy and Astrophysics. 498 (3): 961. Bibcode:2009A&A...498..961R. doi:10.1051/0004-6361/200810788.
  15. ^ Ian Ridpath's Startales - Perseus