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CX Draconis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Draco
Right ascension 18h 46m 43.089s[1]
Declination +52° 59′ 16.65″[1]
Apparent magnitude (V) 5.68 to 5.99[2]
Characteristics
Spectral type B2.5 V + F5 III[3]
Variable type γ Cas + rotating ellipsoidal[2]
Astrometry
Radial velocity (Rv)−2.1±2.3[4] km/s
Proper motion (μ) RA: 10.965 mas/yr[1]
Dec.: −4.920 mas/yr[1]
Parallax (π)2.8262 ± 0.0587 mas[1]
Distance1,150 ± 20 ly
(354 ± 7 pc)
Orbit[5]
Period (P)6.695957±0.000043 d
Semi-major axis (a)≥ 3.253 Gm[6]
Eccentricity (e)0.052±0.006
Inclination (i)52 to 55°
Periastron epoch (T)2,442,549.48±0.24 HJD
Argument of periastron (ω)
(secondary)		267.9±6.4°
Semi-amplitude (K1)
(primary)		33.66±0.86 km/s
Semi-amplitude (K2)
(secondary)		145.92±0.82 km/s
Details
Primary
Mass5.7 to 6.2[7] M☉
Surface gravity (log g)3.71±0.27[8] cgs
Temperature19,580±640[8] K
Rotational velocity (v sin i)163±10[8] km/s
Secondary
Temperature6,500[7] K
Rotational velocity (v sin i)~65[7] km/s
Other designations
CX Dra, BD+52°2280, FK5 1492, GC 25757, HD 174237, HIP 92133, HR 7084, SAO 31165[9]
Database references
SIMBADdata

CX Draconis is an interacting binary star system in the northern constellation of Draco, abbreviated CX Dra. It has the designation HD 174237 in the Henry Draper Catalogue; CX Draconis is the variable star designation. This is a double-lined spectroscopic binary system with a near circular orbit.[5] The brightness of the system undergoes long-term irregular fluctuations,[7] ranging in brightness from an apparent visual magnitude of 5.68 down to 5.99.[2] Based on parallax measurements, it is located at a distance of approximately 1,150 light years from the Sun.[1]

In 1921, this target was found to have a varying radial velocity by J. S. Plaskett and associates.[10][11] It was shown to be a Be star by O. C. Mohler in 1940,[12] and in 1965 M. Lacoarret studied variations in the hydrogen alpha emission profiles from the target. This system was discovered to be a photometric variable by P. Merlin in 1975.[11] P. Koubský measured the radial velocity variations in 1976,[13] and in 1978 published orbital elements for this binary system with a period of 6.696 days.[14] He found that the variation in emission lines matched the time scale of the orbit, indicating that this is an interacting binary.[7]

Using observations from the Einstein Observatory, in 1984 this system was shown to be an X-ray source by E. F. Guinan and associates. This emission may be coming from the cooler secondary that is phase-locked with the primary and is magnetically active due to rapid rotation.[15] In 1992, J. Horn and associates determined that the secondary component is an evolved F-type giant star. Evidence suggests this star is overflowing its Roche lobe with gas streaming toward the primary.[7]

Models indicate that the main source of the H-alpha emission is located mid-way between the two stars, with other emission lines originating from an accretion disk orbiting the primary. The circumstellar environment is changing in cycles lasting hundreds of days.[5]

References

  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b c Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  3. ^ Berdyugin, A.; Piirola, V. (October 2002), "Polarization variability in the interacting Be binary CX Draconis", Astronomy and Astrophysics, 394: 181–186, Bibcode:2002A&A...394..181B, doi:10.1051/0004-6361:20021109.
  4. ^ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 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.
  5. ^ a b c Richards, Mercedes T.; Koubský, Pavel; Šimon, Vojtěch; Peters, Geraldine J.; Hirata, Ryuko; Škoda, Petr; Masuda, Seiji (March 2000), "A Multiwavelength Study of Spectral Variations in the CX Draconis Binary", The Astrophysical Journal, 531 (2): 1003–1027, Bibcode:2000ApJ...531.1003R, doi:10.1086/308491.
  6. ^ Abt, Helmut A.; Gomez, Ana E.; Levy, Saul G. (October 1990), "The Frequency and Formation Mechanism of B2--B5 Main-Sequence Binaries", Astrophysical Journal Supplement, 74: 551, Bibcode:1990ApJS...74..551A, doi:10.1086/191508.
  7. ^ a b c d e f Horn, J.; Hubert, A. M.; Hubert, H.; Koubsky, P.; Bailloux, N. (June 1992), "CX Draconis : the orbit parameters for both components", Astronomy and Astrophysics, 259: L5–L8, Bibcode:1992A&A...259L...5H.
  8. ^ a b c Zorec, J.; et al. (November 2016), "Critical study of the distribution of rotational velocities of Be stars. I. Deconvolution methods, effects due to gravity darkening, macroturbulence, and binarity", Astronomy & Astrophysics, 595: 26, Bibcode:2016A&A...595A.132Z, doi:10.1051/0004-6361/201628760.
  9. ^ "CX Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-02-14.
  10. ^ Plaskett, J. S.; Harper, W. E.; Young, R. K.; Plaskett, H. H. (1921), "Eighty-eight spectroscopic binaries", Publications of the Dominion Astrophysical Observatory Victoria, 1: 287–306, Bibcode:1921PDAO....1..287P.
  11. ^ a b Merlin, P. (February 1975), "Variations photométriques de l'étoile B à émission HD 174237", Astronomy and Astrophysics (in French), 39: 139–141, Bibcode:1975A&A....39..139M.
  12. ^ Mohler, Orren C. (September 1940), "Six New BE Stars", Astrophysical Journal, 92: 315, Bibcode:1940ApJ....92..315M, doi:10.1086/144221.
  13. ^ Koubský, P. (October 1976), "HD 174237 (MWC 608)", Information Bulletin on Variable Stars, 1188 (1), Bibcode:1976IBVS.1188....1K.
  14. ^ Koubský, P. (1978), "Properties and Nature of Be and Shell Stars. 9. Periodic Radial-velocity Changes of HD 174237", Bulletin of the Astronomical Institute of Czechoslovakia, 29: 288, Bibcode:1978BAICz..29..288K.
  15. ^ Guinan, E. F.; Koch, R. H.; Plavec, M. J. (July 1984), "Einstein observations of selected close binaries and shell stars", Astrophysical Journal, 282: 667–674, Bibcode:1984ApJ...282..667G, doi:10.1086/162246.

Further reading

  • Pustylnik, I.; Kalv, P.; Harvig, V.; Aas, T. (2007), "On Quasi-Periodic Intrinsic Light Variability in a Close Spectroscopic Binary CX DRA", Odessa Astronomical Publications, 20: 186, Bibcode:2007OAP....20..186P.
  • Berdyugin, A.; Piirola, V. (October 2002), "Polarization variability in the interacting Be binary CX Draconis", Astronomy and Astrophysics, 394: 181–186, Bibcode:2002A&A...394..181B, doi:10.1051/0004-6361:20021109.
  • Skoda, Petr; Koubsky, Pavel (2000), Smith, M. A.; Henrichs, H. F.; Fabregat, J. (eds.), "IUE Spectra of Be Star CX Dra: Evidence for Winds" (PDF), The Be Phenomenon in Early-Type Stars, IAU Colloquium 175, ASP Conference Series, vol. 214, retrieved 2023-02-15.
  • Iwamatsu, H.; Hirata, R.; Masuda, S. (2000), Smith, Myron A.; Henrichs, Huib F. (eds.), "Origin of Circumstellar Matter in the Spectroscopic Binary CX Dra", The Be Phenomenon in Early-Type Stars, IAU Colloquium 175, ASP Conference Proceedings, vol. 214, Astronomical Society of the Pacific, p. 701, Bibcode:2000ASPC..214..701I, ISBN 1-58381-045-5.
  • Koubský, P.; Richards, M. T.; Šimon, V. (February 1998), Dusek, J.; Zejda, M. (eds.), "Circumstellar Matter in the Interacting Binary CX Draconis", Proceedings of the 29th Conference on Variable Star Research. 7th - 9th November 1997. Brno, Czech Republic, p. 64, Bibcode:1998stel.conf...64K, ISBN 80-85882-09-4.
  • Koubsky, P.; Harmanec, P.; Bozic, H.; Rercy, J. R.; Ziznovsky, J.; Huang, L.; Richards, M. T.; Hadrava, P.; Simon, V. (1998), "Spectroscopy and Photometry of the Interacting Binary CX Draconis - Evidence for Circumstellar Mater", Hvar Observatory Bulletin, 22 (1): 17–36, Bibcode:1998HvaOB..22...17K.
  • Simon, V. (April 1996), "The interacting binary CX Draconis: new orbital elements and evidence for mass transfer.", Astronomy and Astrophysics, 308: 799–808, Bibcode:1996A&A...308..799S.
  • Koubský, P.; Horn, J.; Harmanec, P.; Peters, G. J.; Polidan, R. S. (1990), İbanoğlu, C (ed.), "Interacting Binary CX Draconis", Active Close Binaries, NATO ASI Series, vol. 319, Dordrecht: Springer, doi:10.1007/978-94-009-0679-2_18.
  • Magalashvili, N. L.; Kumsishvili, Ya. I. (1986), "Photometric observations of the emission B star CX Dra (HD 174237)", Byulleten Abastumanskaya Astrofizicheskaya Observatoriya, 61: 79–82, Bibcode:1986AbaOB..61...79M.
  • Harmanec, P.; Horn, J.; Koubsky, P.; Ziznovsky, J. (March 1981), "Call for Systematic Photoelectric Observations of CX Dra", Information Bulletin on Variable Stars, 1931: 1, Bibcode:1981IBVS.1931....1H.
  • Koubský, P.; Harmanec, P.; Horn, J.; Jerzykiewicz, M.; Papoušek, J.; Kříž, S.; Pavlovski, K.; Ždárský, F. (1980), "Properties and Nature of Be and Shell Stars. 10. Light and Colour Variations of CX Dra", Bulletin of the Astronomical Institute of Czechoslovakia, 31 (2): 75–84, Bibcode:1980BAICz..31...75K.
  • Koubský, P.; Harmanec, P.; Horn, J.; Jerzykiewicz, M.; Kríz, S.; Pavlovski, K.; Zdárský, F. (1980), "UBV photometry of CX Cra. Search for rapid variations" (PDF), Acta Universitatis Carolinae, Mathematica et Physica, 21 (2): 33–54, Bibcode:1980AcMPh..21...33K, retrieved 2023-02-15.


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