Chi Serpentis

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Chi Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension 15h 41m 47.41465s[1]
Declination +12° 50′ 51.1057″[1]
Apparent magnitude (V) +5.30[2]
Spectral type A2 Vp MnEu(Sr)[3]
U−B color index +0.04[2]
B−V color index +0.04[2]
Variable type α2 CVn[4]
Radial velocity (Rv) +1.90±1.78[5] km/s
Proper motion (μ) RA: +38.42[1] mas/yr
Dec.: −3.76[1] mas/yr
Parallax (π) 14.84 ± 0.41[1] mas
Distance 220 ± 6 ly
(67 ± 2 pc)
Absolute magnitude (MV) +1.10[6]
Mass 2.11[7] M
Radius 1.9[8] R
Luminosity 26[9] L
Surface gravity (log g) 3.66±0.24[10] cgs
Temperature 9,557±274[10] K
Metallicity [Fe/H] +0.35±0.13[10] dex
Rotation 1.5948[6] d
Rotational velocity (v sin i) 75[11] km/s
Age 212[7] Myr
Other designations
χ Ser, 20 Ser, BD+13° 2982, FK5 3243, HD 140160, HIP 76866, HR 5843, SAO 101683.[12]
Database references

Chi Serpentis (χ Ser, χ Serpentis) is a solitary[13] star in the Serpens Caput section of the equatorial constellation Serpens. Based upon an annual parallax shift of 14.84 mas as seen from Earth, it is located around 220 light years from the Sun. The star is bright enough to be faintly visible to the naked eye, having an apparent visual magnitude of +5.30.[2]

In 1966 it was listed as a suspected spectroscopic binary,[14] but it is believed to be single.[13] This is a chemically peculiar star Ap star with a stellar classification of A2 Vp MnEu(Sr),[3] indicating the spectrum shows abnormal excesses of manganese and europium. The star has 2.11[7] times the mass of the Sun and about 1.9 times the Sun's radius.[8] It is radiating 26[9] times the solar luminosity from its photosphere at an effective temperature of 9,557 K.[10] At the age of 212[7] million years, it is spinning with a rotation period of 1.6 days.[14]

Chi Serpentis is classified as an Alpha2 Canum Venaticorum type variable star,[4] and its magnitude varies by 0.03 with a period of 1.5948 days.[6] The pattern of variation in the spectrum suggest there are regions of enhanced strontium, chromium, iron, titanium, and magnesium on the surface of the star.[15] The averaged quadratic field strength of the surface magnetic field is (859.1±712.3)×10−4 T.[16]


  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data, SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ a b Loden, L. O. (July 1983), "A physical study of the Ursa Major cluster (with special attention to the peculiar A stars)", Astronomy and Astrophysics Supplement Series, 53: 33−42, Bibcode:1983A&AS...53...33L. 
  4. ^ a b Hoffleit, D. (October 1982), "Variable stars in the General Catalogue of Trigonometric Parallaxes", Bulletin d'Information du Centre de Donnees Stellaires, 23: 53, Bibcode:1982BICDS..23...53H. 
  5. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048Freely accessible, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61. 
  6. ^ a b c Adelman, Saul J. (2002), "On the Periods of the Magnetic CP Stars", Baltic Astronomy, 11: 475−485, Bibcode:2002BaltA..11..475A. 
  7. ^ a b c d 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:1501.03154Freely accessible, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146. 
  8. ^ a b Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. 
  9. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037Freely accessible, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  10. ^ a b c d Prugniel, Ph.; et al. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952Freely accessible, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769. 
  11. ^ Royer, F.; et al. (October 2012), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897−911, arXiv:astro-ph/0205255Freely accessible, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943. 
  12. ^ "chi Ser -- Variable Star of alpha2 CVn type", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-03-23. 
  13. ^ a b 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:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  14. ^ a b Rajamohan, R.; Babu, G. S. D. (March 1978), "On the intrinsic rotation of magnetic variables", Monthly Notices of the Royal Astronomical Society, 182: 773−776, Bibcode:1978MNRAS.182..773R, doi:10.1093/mnras/182.4.773. 
  15. ^ Riabchikova, T. A. (February 1975), "The spectroscopic variable AP star chi Serpentis", Soviet Astronomy, 18: 451−453, Bibcode:1975SvA....18..451R. 
  16. ^ Bychkov, V. D.; et al. (April 2009), "Catalogue of averaged stellar effective magnetic fields - II. Re-discussion of chemically peculiar A and B stars", Monthly Notices of the Royal Astronomical Society, 394 (3): 1338–1350, Bibcode:2009MNRAS.394.1338B, doi:10.1111/j.1365-2966.2008.14227.x.