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.[7] The brightness of the system undergoes long-term irregular fluctuations,[11] ranging from an apparent visual magnitude of 5.68 down to 5.99.[4] Based on parallax measurements, it is located at a distance of approximately 1,150 light years from the Sun.[3]

CX Draconis

Light curves for CX Draconis. The main plot, from Hipparcos data,[1] shows the long-term variability. The inset plot, from TESS data,[2] shows how the brightness changes of short timescales.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Draco
Right ascension 18h 46m 43.089s[3]
Declination +52° 59′ 16.65″[3]
Apparent magnitude (V) 5.68 to 5.99[4]
Characteristics
Spectral type B2.5 V + F5 III[5]
Variable type γ Cas + rotating ellipsoidal[4]
Astrometry
Radial velocity (Rv)−2.1±2.3[6] km/s
Proper motion (μ) RA: 10.965 mas/yr[3]
Dec.: −4.920 mas/yr[3]
Parallax (π)2.8262 ± 0.0587 mas[3]
Distance1,150 ± 20 ly
(354 ± 7 pc)
Orbit[7]
Period (P)6.695957±0.000043 d
Semi-major axis (a)≥ 3.253 Gm[8]
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
Mass7.3[9] M
Surface gravity (log g)3.71±0.27[10] cgs
Temperature19,580±640[10] K
Rotational velocity (v sin i)163±10[10] km/s
Secondary
Mass~1.7[9] M
Temperature6,500[11] K
Rotational velocity (v sin i)~65[11] km/s
Other designations
CX Dra, BD+52°2280, FK5 1492, GC 25757, HD 174237, HIP 92133, HR 7084, SAO 31165[12]
Database references
SIMBADdata

In 1921, this target was found to have a varying radial velocity by J. S. Plaskett and associates.[13][14] It was shown to be a Be star by O. C. Mohler in 1940,[15] 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.[14] P. Koubský measured the radial velocity variations in 1976,[16] and in 1978 published orbital elements for this binary system with a period of 6.696 days.[17] He found that the variation in emission lines matched the time scale of the orbit, indicating that this is an interacting binary.[11]

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.[18] 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.[11]

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.[7] Infrared emission to the northeast of the system suggests it may be undergoing systematic mass loss.[19]

References

edit
  1. ^ EAS (1997), "The HIPPARCOS and TYCHO catalogues", Astrometric and Photometric Star Catalogues Derived from the ESA Hipparcos Space Astrometry Mission, ESA SP Series, 1200, Noordwijk, Netherlands: ESA Publications Division, Bibcode:1997ESASP1200.....E, ISBN 9290923997, retrieved 15 October 2022.
  2. ^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 8 December 2021.
  3. ^ 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.
  4. ^ 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.
  5. ^ 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.
  6. ^ 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.
  7. ^ 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, S2CID 122795224.
  8. ^ 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.
  9. ^ a b Harmanec, P.; Koubský, P.; Nemravová, J.; Royer, F.; Briot, D.; North, P.; Lampens, P.; Frémat, Y.; Yang, S.; Božić, H.; Kotková, L.; Škoda, P.; Šlechta, M.; Korčáková, D.; Wolf, M.; Zasche, P. (January 2015), "Properties and nature of Be stars 30. Reliable physical properties of a semi-detached B9.5e+G8III binary BR CMi = HD 61273 compared to those of other well studied semi-detached emission-line binaries", Astronomy and Astrophysics, 573, arXiv:1411.5651, Bibcode:2015A&A...573A.107H, doi:10.1051/0004-6361/201424640, S2CID 118456434, A107.
  10. ^ 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" (PDF), Astronomy & Astrophysics, 595: 26, Bibcode:2016A&A...595A.132Z, doi:10.1051/0004-6361/201628760.
  11. ^ a b c d e 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.
  12. ^ "CX Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-02-14.
  13. ^ 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.
  14. ^ 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.
  15. ^ Mohler, Orren C. (September 1940), "Six New BE Stars", Astrophysical Journal, 92: 315, Bibcode:1940ApJ....92..315M, doi:10.1086/144221.
  16. ^ Koubský, P. (October 1976), "HD 174237 (MWC 608)", Information Bulletin on Variable Stars, 1188 (1): 1, Bibcode:1976IBVS.1188....1K.
  17. ^ 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.
  18. ^ 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.
  19. ^ Mayer, A.; Deschamps, R.; Jorissen, A. (March 2016), "Search for systemic mass loss in Algols with bow shocks", Astronomy & Astrophysics, 587: A30, arXiv:1601.00218, Bibcode:2016A&A...587A..30M, doi:10.1051/0004-6361/201526623, S2CID 54596624, A30.

Further reading

edit
  • 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, p. 573, Bibcode:2000ASPC..214..573S, 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, pp. 237–238, doi:10.1007/978-94-009-0679-2_18, ISBN 978-94-010-6790-4.
  • 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.