Astronomy:HD 125248

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Short description: Binary star system in the constellation of Virgo
HD 125248
Libra constellation map.svg
Red circle.svg
Location of HD 125248 (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Virgo
Right ascension  14h 18m 38.251s[1]
Declination −18° 42′ 57.47″[1]
Apparent magnitude (V) 5.84 to 5.95[2]
Characteristics
Evolutionary stage Main sequence[3]
Spectral type A1p SrCrEu[4] or ApSi(Cr)[5]
B−V color index 0.013±0.006[6]
Variable type α2 CVn[2]
Astrometry
Radial velocity (Rv)−8.0±0.8[7] km/s
Proper motion (μ) RA: −52.197[1] mas/yr
Dec.: −46.004[1] mas/yr
Parallax (π)11.497 ± 0.5361[1] mas
Distance280 ± 10 ly
(87 ± 4 pc)
Absolute magnitude (MV)0.83[6]
Orbit[8]
Period (P)4.4 yr
Semi-major axis (a)≥161 Gm (1.08 AU)
Eccentricity (e)0.21±0.01
Periastron epoch (T)2,431,475.0 JD
Argument of periastron (ω)
(secondary)		82.4±3.4°
Semi-amplitude (K1)
(primary)		7.5±0.5 km/s
Details
Mass2.0±0.6[9] M☉
Radius1.95[10] R☉
Luminosity42.0±8.3[9] L☉
Surface gravity (log g)4.05±0.10[9] cgs
Temperature9,850±250[9] K
Rotation9.29558±0.00006 d[9]
Rotational velocity (v sin i)18[11] km/s
Age234[9] Myr
Other designations
CS Vir, BD−18°3789, FK5 1369, GC 19295, HD 125248, HIP 69929, HR 5355, SAO 158481, PPM 228604[12]
Database references
SIMBADdata

HD 125248 is a binary star[13] system in the equatorial constellation of Virgo. It has the variable star designation CS Virginis, while HD 125248 is the designation from the Henry Draper Catalogue. This system is dimly visible to the naked eye as a point of light with an apparent visual magnitude that ranges from 5.84 down to 5.95.[2] It is located at a distance of approximately 280 light years from the Sun based on parallax measurements,[1] but is drifting closer with a heliocentric radial velocity of −8 km/s.[7]

This star was classified as peculiar with spectral type A0p in the Henry Draper Catalogue, published 1918–1924. This class was based on the strength of a pair of lines of ionized silicon in its stellar spectrum. In 1931, W. W. Morgan discovered that the spectrum of the star varied over a period of several days. In particular, the lines of ionized chromium and europium varied considerably in intensity, ranging from strong to very faint. This variation shares similarities to those of α2 Canum Venaticorum. The two sets of lines vary in the opposite direction from each other, so that the chromium lines were minimum when the europium lines were maximized, and vice versa.[14] In 1947, A. J. Deutsch found a period of 9.295 days for the variation.[15]

H. W. Babcock examined the star using Coudé spectrograms in 1947, finding a general magnetic field with a strength of around 5,500 Gauss at the poles. At the time, that was the strongest magnetic field that had been observed in a star. He noticed that the magnetic field was variable, and it showed the opposite polarity when the lines of europium were at a minimum compared to when they were at the maximum.[16] Subsequent observations showed the period and amplitude of the variation to be stable over time.[8] In 1950, D. W. N. Stibbs first proposed an 'oblique rotator model' to explain the properties of this star,[17] in which its magnetic field is locked at an angle to the axis of rotation.[9]

A light curve for CS Virginis, plotted from Hipparcos data[18]

The star displays radial velocity variations that suggest it is a single-lined spectroscopic binary with a period of 4.4 years and an orbital eccentricity of 0.21.[8] The visible component has a stellar classification of A1p SrCrEu,[4] which indicates this is a magnetic peculiar Ap star with prominent abundance anomalies of strontium, chromium, and europium in its atmosphere. It has double the mass and nearly twice the radius of the Sun.[9][10] The star is an estimated 234 million years old and is spinning with a rotation rate of 9.3 days.[9] It is radiating 42 times the luminosity of the Sun from its photosphere at an effective temperature of 9,850 K.[9]

This is an Alpha2 Canum Venaticorum variable star with a brightness that is modulated by its rotation.[2] Magnetic Doppler imaging of the star suggests the magnetic field deviates strongly from a simple dipole geometry.[9]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S. 
  3. ↑ Ozuyar, D. et al. (2018), "Photometric Variability of the MCP Star CS vir: Evolution of the Rotation Period", Publications of the Astronomical Society of Australia 35, doi:10.1017/pasa.2017.69, Bibcode: 2018PASA...35....4O. 
  4. ↑ 4.0 4.1 Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics 498 (3): 961–966, doi:10.1051/0004-6361/200810788, Bibcode: 2009A&A...498..961R. 
  5. ↑ Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode: 1988mcts.book.....H. 
  6. ↑ 6.0 6.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G. 
  8. ↑ 8.0 8.1 8.2 Hockey, M. S. (1969), "Spectrophotometric observations of the magnetic variable HD 125248", Monthly Notices of the Royal Astronomical Society 142 (4): 543, doi:10.1093/mnras/142.4.543, Bibcode: 1969MNRAS.142..543H. 
  9. ↑ 9.00 9.01 9.02 9.03 9.04 9.05 9.06 9.07 9.08 9.09 9.10 Rusomarov, N. et al. (April 2016), "Magnetic Doppler imaging of the chemically peculiar star HD 125248", Astronomy & Astrophysics 588: 20, doi:10.1051/0004-6361/201527719, A138, Bibcode: 2016A&A...588A.138R. 
  10. ↑ 10.0 10.1 Shulyak, D. et al. (2014), "Interferometry of chemically peculiar stars: Theoretical predictions versus modern observing facilities", Monthly Notices of the Royal Astronomical Society 443 (2): 1629, doi:10.1093/mnras/stu1259, Bibcode: 2014MNRAS.443.1629S. 
  11. ↑ Royer, F. et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics 393 (3): 897–911, doi:10.1051/0004-6361:20020943, Bibcode: 2002A&A...393..897R. 
  12. ↑ "CS Vir". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=CS+Vir. 
  13. ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  14. ↑ Morgan, W. W. (July 1931), "Studies in Peculiar Stellar Spectra. II. The Spectrum of B. D. 18°3789", Astrophysical Journal 74: 24, doi:10.1086/143322, Bibcode: 1931ApJ....74...24M. 
  15. ↑ Deutsch, Armin J. (March 1947), "A Study of the Spectrum Variables of Type A", Astrophysical Journal 105: 283, doi:10.1086/144904, Bibcode: 1947ApJ...105..283D. 
  16. ↑ Babcock, Horace W. (October 1947), "The Reversing Magnetic Field of BD-18°3789", Publications of the Astronomical Society of the Pacific 59 (350): 260, doi:10.1086/125963, Bibcode: 1947PASP...59..260B. 
  17. ↑ Stibbs, D. W. N. (1950), "A study of the spectrum and magnetic variable star HD 125248", Monthly Notices of the Royal Astronomical Society 110 (4): 395, doi:10.1093/mnras/110.4.395, Bibcode: 1950MNRAS.110..395S. 
  18. ↑ Light Curve, ESA, https://www.cosmos.esa.int/web/hipparcos/java-tools/light-curve, retrieved 17 February 2022. 

Further reading

  • Monier, R. (September 1992), "Applications of the infrared flux method to 3 cool AP stars (78 Virginis, 52 Herculis A and CS Virginis) and comparison of their energy distributions to model atmospheres", Astronomy and Astrophysics 263: 175–182, Bibcode: 1992A&A...263..175M. 
  • Mathys, G. (March 1992), "The inhomogeneous distribution of oxygen on the surface of the magnetic AP star HD 125248", Astronomy and Astrophysics 256: L31–L34, Bibcode: 1992A&A...256L..31M. 
  • Catalano, F. A. et al. (September 1992), "The near-infrared variation of the magnetic star HD 125248", Astronomy and Astrophysics 263: 203–207, Bibcode: 1992A&A...263..203C. 
  • Mathys, G.; Stenflo, J. O. (1988), de Strobel, G. Cayrel; Spite, Monique, eds., "Spectropolarimetry of Magnetic Stars: HD 125248", The Impact of Very High S/N Spectroscopy on Stellar Physics: Proceedings of the 132nd Symposium of the International Astronomical Union held in Paris, France, June 29-July 3, 1987. International Astronomical Union Symposium no. 132 (Dordrecht: Kluwer Academic Publishers) 132: p. 317, Bibcode: 1988IAUS..132..317M. 
  • Pyper, D. M.; Adelman, S. J. (March 1985), "Spectrophotometry of peculiar B and A stars. XVII. 63 Andromedae, HD 34452, epsilon Ursae Majoris, CQ Ursae Majoris, CU Virginis, CS Virginis and beta Coronae Borealis", Astronomy and Astrophysics Supplement Series 59: 369–397, Bibcode: 1985A&AS...59..369P. 
  • Blanco, C. et al. (February 1978), "Photoelectric observations of the Ap stars HD 125248, HD 134798 and HD 184905", Astronomy and Astrophysics Supplement Series 31: 205–208, Bibcode: 1978A&AS...31..205B. 
  • Pilachowski, C. A.; Bonsack, W. K. (April 1975), "The effect of line blocking on the light curves of the Ap star HR 5355 (HD 125248)", Publications of the Astronomical Society of the Pacific 87: 221–229, doi:10.1086/129747, Bibcode: 1975PASP...87..221P. 
  • Maitzen, H. M.; Moffat, A. F. J. (February 1972), "Eleven-band photometry of the magnetic variable HD 125248", Astronomy and Astrophysics 16: 385, Bibcode: 1972A&A....16..385M. 
  • Maitzen, H. M.; Rakosch, K. D. (July 1970), "UBV observations of the magnetic variable HD 125248", Astronomy and Astrophysics 7: 10, Bibcode: 1970A&A.....7...10M. 
  • Preston, George W. (June 1970), "The Large Variable Magnetic Field of HD 126515 and its Implications for the Rigid-Rotator Model of Magnetic Stars", Astrophysical Journal 160: 1059, doi:10.1086/150493, Bibcode: 1970ApJ...160.1059P. 
  • Maitzen, H. M. (February 1970), "Observations Photoelectriques de HD 125248", Information Bulletin on Variable Stars 421 (1): 1, Bibcode: 1970IBVS..421....1M. 
  • Hockey, M. S. (1969), "Spectrophotometric observations of the magnetic variable HD 125248", Monthly Notices of the Royal Astronomical Society 142 (4): 543, doi:10.1093/mnras/142.4.543, Bibcode: 1969MNRAS.142..543H. 
  • Adam, M. G. (October 1965), "The magnetic variable HD 125248", The Observatory 85: 204–206, Bibcode: 1965Obs....85..204A. 
  • Babcock, Horace W. (July 1951), "The Magnetically Variable Star HD 125248", Astrophysical Journal 114: 1, doi:10.1086/145448, Bibcode: 1951ApJ...114....1B. 




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