CX Draconis

{{Short description|Binary star system in the constellation Draco}} {{Use dmy dates|date=January 2025}} {{Starbox begin}} {{Starbox image | image = [[File:CXDraLightCurve.png|250px]] | caption = [[Light curve]]s for CX Draconis. The main plot, from ''[[Hipparcos]]'' data,<ref name=CDS/> shows the long-term variability. The inset plot, from ''[[Transiting Exoplanet Survey Satellite|TESS]]'' data,<ref name=MAST/> shows how the brightness changes of short timescales. }} {{Starbox observe | epoch = [[J2000.0]] | constell = [[Draco (constellation)|Draco]] | ra = {{RA|18|46|43.089}}<ref name=GaiaEDR3/> | dec = {{DEC|+52|59|16.65}}<ref name=GaiaEDR3/> | appmag_v = {{val|5.68|to|5.99}}<ref name=Samus_et_al_2017/> }} {{Starbox character | type = | class = {{nowrap|B2.5 V + F5 III}}<ref name=Berdyugin_Piirola_2002/> | b-v = | u-b = | variable = [[Gamma Cassiopeiae variable|γ Cas]] + [[Rotating ellipsoidal variable|rotating ellipsoidal]]<ref name=Samus_et_al_2017/> }} {{Starbox astrometry | radial_v = −2.1{{±|2.3}}<ref name=Gontcharov_2006/> | prop_mo_ra = 10.965 | prop_mo_dec = −4.920 | pm_footnote = <ref name=GaiaEDR3/> | parallax = 2.8262 | p_error = 0.0587 | parallax_footnote = <ref name=GaiaEDR3/> | absmag_v = }} {{Starbox orbit | reference = <ref name=Richards_et_al_2000/> | period =  | period_unitless = {{val|6.695957|0.000043|u=days|fmt=commas}} | axis =  | axis_unitless = ≥ 3.253 million km<ref name=Abt_et_al_1990/> | eccentricity = 0.052{{±|0.006}} | inclination = {{val|52|to|55}} | node =  | periastron = {{val|2442549.48|0.24|ul=HJD|fmt=commas}} | periarg = 267.9{{±|6.4}} | periarg_primary =  | k1 = 33.66{{±|0.86}} | k2 = 145.92{{±|0.82}} }} {{Starbox detail | source = | component1 = Primary | mass = 7.3<ref name=Harmanec_et_al_2014/> | radius = | luminosity = | temperature = 19,580{{±|640}}<ref name=Zorec_et_al_2016/> | gravity = 3.71{{±|0.27}}<ref name=Zorec_et_al_2016/> | metal_fe = | rotational_velocity = 163{{±|10}}<ref name=Zorec_et_al_2016/> | age_gyr = | component2 = Secondary | mass2 = ~1.7<ref name=Harmanec_et_al_2014/> | radius2 = | luminosity2 = | temperature2= 6,500<ref name=Horn_et_al_1992/> | rotational_velocity2 = ~65<ref name=Horn_et_al_1992/> }} {{Starbox catalog | names = {{odlist | V=CX Dra | BD=+52°2280 | FK5=1492 | GC=25757 | HD=174237 | HIP=92133 | HR=7084 | SAO=31165 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad=CX+Dra }} {{Starbox end}}

'''CX Draconis''' is an [[interacting binary star]] system in the northern [[constellation]] of [[Draco (constellation)|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.<ref name=Richards_et_al_2000/> The brightness of the system undergoes long-term irregular fluctuations,<ref name=Horn_et_al_1992/> ranging from an [[apparent visual magnitude]] of 5.68 down to 5.99.<ref name=Samus_et_al_2017/> Based on [[stellar parallax|parallax]] measurements, it is located at a distance of approximately 1,150 [[light year]]s from the [[Sun]].<ref name=GaiaEDR3/>

In 1921, this target was found to have a varying [[radial velocity]] by [[John Stanley Plaskett|J. S. Plaskett]] and associates.<ref name=Plaskett_et_al_1921/><ref name=Merlin_1975/> It was shown to be a [[Be star]] by [[Orren Cuthbert Mohler|O. C. Mohler]] in 1940,<ref name=Mohler_1940/> and in 1965 [[Marie Lacoarret|M. Lacoarret]] studied variations in the [[hydrogen alpha]] emission profiles from the target. This system was discovered to be a [[Photometry (astronomy)|photometric]] [[Variable star|variable]] by P. Merlin in 1975.<ref name=Merlin_1975/> [[Pavel Koubský|P. Koubský]] measured the radial velocity variations in 1976,<ref name=Koubsky_1976/> and in 1978 published [[orbital elements]] for this binary system with a [[orbital period|period]] of 6.696 days.<ref name=Koubsky_1978/> He found that the variation in emission lines matched the time scale of the orbit, indicating that this is an interacting binary.<ref name=Horn_et_al_1992/>

Using observations from the [[Einstein Observatory]], in 1984 this system was shown to be an [[X-ray astronomy|X-ray source]] by [[Edward Guinan|E. F. Guinan]] and associates. This emission may be coming from the cooler secondary that is [[tidally locked|phase-locked]] with the primary and is [[magnetic activity|magnetically active]] due to rapid rotation.<ref name=Guinan_et_al_1984/> In 1992, [[Jiří Horn|J. Horn]] and associates determined that the secondary component is an [[stellar evolution|evolved]] [[F-type star|F-type]] [[giant star]]. Evidence suggests this star is overflowing its [[Roche lobe]] with gas streaming toward the primary.<ref name=Horn_et_al_1992/>

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.<ref name=Richards_et_al_2000/> Infrared emission to the northeast of the system suggests it may be undergoing systematic mass loss.<ref name=Mayer_et_al_2016/>

==References== <references>

<ref name=SIMBAD>{{cite simbad | title=CX Dra | access-date=2023-02-14 }}</ref>

<ref name=Samus_et_al_2017>{{citation | display-authors=1 | last1=Samus | first1=N. N. | last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V. | last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N. | title=General Catalogue of Variable Stars | version=5.1 | journal=[[Astronomy Reports]] | year=2017 | volume=61 | issue=1 | pages=80–88 | bibcode=2017ARep...61...80S | doi=10.1134/S1063772917010085 | s2cid=125853869 | postscript=. }}</ref>

<ref name=Gontcharov_2006>{{citation | last1=Gontcharov | first1=G. A. | title=Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system | journal=Astronomy Letters | postscript=. | volume=32| issue=11| pages=759–771| date=November 2006 | doi=10.1134/S1063773706110065 | arxiv=1606.08053 | bibcode=2006AstL...32..759G | s2cid=119231169 }}</ref>

<ref name=Berdyugin_Piirola_2002>{{citation | postscript=. | title=Polarization variability in the interacting Be binary CX Draconis | last1=Berdyugin | first1=A. | last2=Piirola | first2=V. | journal=Astronomy and Astrophysics | volume=394 | pages=181–186 | date=October 2002 | doi=10.1051/0004-6361:20021109 | bibcode=2002A&A...394..181B | doi-access=free }}</ref>

<ref name=Zorec_et_al_2016>{{citation | postscript=. | title=Critical study of the distribution of rotational velocities of Be stars. I. Deconvolution methods, effects due to gravity darkening, macroturbulence, and binarity | journal=Astronomy & Astrophysics | display-authors=1 | last1=Zorec | first1=J. | last2=Frémat | first2=Y. | last3=Domiciano de Souza | first3=A. | last4=Royer | first4=F. | last5=Cidal | first5=L. | last6=Hubert | first6=A. -M. | last7=Seemann | first7=T. | last8=Martayan | first8=C. | last9=Cochetti | first9=Y. R. | last10=Arias | first10=M. L. | last11=Aidelman | first11=Y. | last12=Stee | first12=P. | volume=595 | date=November 2016 | pages=26 | doi=10.1051/0004-6361/201628760 | doi-access=free | bibcode=2016A&A...595A.132Z | url=http://sedici.unlp.edu.ar/bitstream/handle/10915/85970/Documento_completo.pdf?sequence=1 }}</ref>

<ref name=Abt_et_al_1990>{{citation | postscript=. | title=The Frequency and Formation Mechanism of B2--B5 Main-Sequence Binaries | last1=Abt | first1=Helmut A. | last2=Gomez | first2=Ana E. | last3=Levy | first3=Saul G. | journal=Astrophysical Journal Supplement | volume=74 | page=551 | date=October 1990 | doi=10.1086/191508 | bibcode=1990ApJS...74..551A }}</ref>

<ref name=Merlin_1975>{{citation | postscript=. | title=Variations photométriques de l'étoile B à émission HD 174237 | last=Merlin | first=P. | language=Fr | journal=Astronomy and Astrophysics | volume=39 | pages=139–141 | date=February 1975 | bibcode=1975A&A....39..139M }}</ref>

<ref name=Mohler_1940>{{citation | postscript=. | title=Six New BE Stars | last=Mohler | first=Orren C. | journal=Astrophysical Journal | volume=92 | page=315 | date=September 1940 | doi=10.1086/144221 | bibcode=1940ApJ....92..315M | doi-access=free}}</ref>

<ref name=Plaskett_et_al_1921>{{citation | postscript=. | title=Eighty-eight spectroscopic binaries | last1=Plaskett | first1=J. S. | last2=Harper | first2=W. E. | last3=Young | first3=R. K. | last4=Plaskett | first4=H. H. | journal=Publications of the Dominion Astrophysical Observatory Victoria | volume=1 | pages=287–306 | year=1921 | bibcode=1921PDAO....1..287P }}</ref>

<ref name=Koubsky_1976>{{citation | postscript=. | title=HD 174237 (MWC 608) | last=Koubský | first=P. | journal=Information Bulletin on Variable Stars | volume=1188 | issue=1 | date=October 1976 | page=1 | bibcode=1976IBVS.1188....1K }}</ref>

<ref name=Koubsky_1978>{{citation | postscript=. | title=Properties and Nature of Be and Shell Stars. 9. Periodic Radial-velocity Changes of HD 174237 | last=Koubský | first=P. | journal=Bulletin of the Astronomical Institute of Czechoslovakia | volume=29 | page=288 | year=1978 | bibcode=1978BAICz..29..288K }}</ref>

<ref name=Horn_et_al_1992>{{citation | postscript=. | title=CX Draconis : the orbit parameters for both components | last1=Horn | first1=J. | last2=Hubert | first2=A. M. | last3=Hubert | first3=H. | last4=Koubsky | first4=P. | last5=Bailloux | first5=N. | journal=Astronomy and Astrophysics | volume=259 | pages=L5–L8 | date=June 1992 | bibcode=1992A&A...259L...5H }}</ref>

<ref name=Guinan_et_al_1984>{{citation | postscript=. | title=Einstein observations of selected close binaries and shell stars | last1=Guinan | first1=E. F. | last2=Koch | first2=R. H. | last3=Plavec | first3=M. J. | journal=Astrophysical Journal | volume=282 | pages=667–674 | date=July 1984 | doi=10.1086/162246 | bibcode=1984ApJ...282..667G }}</ref>

<ref name=Richards_et_al_2000>{{citation | postscript=. | title=A Multiwavelength Study of Spectral Variations in the CX Draconis Binary | last1=Richards | first1=Mercedes T. | last2=Koubský | first2=Pavel | last3=Šimon | first3=Vojtěch | last4=Peters | first4=Geraldine J. | last5=Hirata | first5=Ryuko | last6=Škoda | first6=Petr | last7=Masuda | first7=Seiji | journal=The Astrophysical Journal | volume=531 | issue=2 | pages=1003–1027 | date=March 2000 | doi=10.1086/308491 | bibcode=2000ApJ...531.1003R | s2cid=122795224 | doi-access=free }}</ref>

<ref name=Mayer_et_al_2016>{{citation | postscript=. | title=Search for systemic mass loss in Algols with bow shocks | last1=Mayer | first1=A. | last2=Deschamps | first2=R. | last3=Jorissen | first3=A. | journal=Astronomy & Astrophysics | volume=587 | id=A30 | date=March 2016 | pages=A30 | doi=10.1051/0004-6361/201526623 | arxiv=1601.00218 | bibcode=2016A&A...587A..30M | s2cid=54596624 }}</ref>

<ref name=Harmanec_et_al_2014>{{citation | postscript=. | title=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 | first1=P. | last1=Harmanec | first2=P. | last2=Koubský | first3=J. | last3=Nemravová | first4=F. | last4=Royer | first5=D. | last5=Briot | first6=P. | last6=North | first7=P. | last7=Lampens | first8=Y. | last8=Frémat | first9=S. | last9=Yang | first10=H. | last10=Božić | first11=L. | last11=Kotková | first12=P. | last12=Škoda | first13=M. | last13=Šlechta | first14=D. | last14=Korčáková | first15=M. | last15=Wolf | first16=P. | last16=Zasche | journal=Astronomy and Astrophysics | date=January 2015 | volume=573 | id=A107 | doi=10.1051/0004-6361/201424640 | arxiv=1411.5651 | bibcode=2015A&A...573A.107H | s2cid=118456434 }}</ref>

<ref name=MAST>{{citation | postscript=. | title=MAST: Barbara A. Mikulski Archive for Space Telescopes | url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html | publisher=Space Telescope Science Institute | access-date=8 December 2021}}</ref>

<ref name=CDS>{{citation | postscript=. | title=The HIPPARCOS and TYCHO catalogues | author=EAS | journal=Astrometric and Photometric Star Catalogues Derived from the ESA Hipparcos Space Astrometry Mission | publication-place=Noordwijk, Netherlands | publisher=ESA Publications Division | year=1997 | series=ESA SP Series | volume=1200 | isbn=9290923997 | bibcode=1997ESASP1200.....E | url=https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats | access-date=15 October 2022}}</ref>

</references>

==Further reading== {{Div col|small=yes}} *{{citation | postscript=. | title=On Quasi-Periodic Intrinsic Light Variability in a Close Spectroscopic Binary CX DRA | last1=Pustylnik | first1=I. | last2=Kalv | first2=P. | last3=Harvig | first3=V. | last4=Aas | first4=T. | journal=Odessa Astronomical Publications | volume=20 | page=186 | year=2007 | bibcode=2007OAP....20..186P }} *{{citation | postscript=. | title=Polarization variability in the interacting Be binary CX Draconis | last1=Berdyugin | first1=A. | last2=Piirola | first2=V. | journal=Astronomy and Astrophysics | volume=394 | pages=181–186 | date=October 2002 | doi=10.1051/0004-6361:20021109 | bibcode=2002A&A...394..181B | doi-access=free }} *{{citation | postscript=. | title=IUE Spectra of Be Star CX Dra: Evidence for Winds | first1=Petr | last1=Skoda | first2=Pavel | last2=Koubsky | work=The Be Phenomenon in Early-Type Stars, IAU Colloquium 175 | volume=214 | year=2000 | editor1-first=M. A. | editor1-last=Smith | editor2-first=H. F. | editor2-last=Henrichs | editor3-first=J. | editor3-last=Fabregat | series=ASP Conference Series | page=573 | bibcode=2000ASPC..214..573S | url=https://www.cambridge.org/core/services/aop-cambridge-core/content/view/C43B07F8914B2D2B299445329B6398F7/S0252921100056542a.pdf | access-date=2023-02-15 }} *{{citation | postscript=. | title=Origin of Circumstellar Matter in the Spectroscopic Binary CX Dra | last1=Iwamatsu | first1=H. | last2=Hirata | first2=R. | last3=Masuda | first3=S. | work=The Be Phenomenon in Early-Type Stars, IAU Colloquium 175 | series=ASP Conference Proceedings | editor1-first=Myron A. | editor1-last=Smith | editor2-first=Huib F. | editor2-last=Henrichs | publisher=Astronomical Society of the Pacific | isbn=1-58381-045-5 | page=701 | volume=214 | year=2000 | bibcode=2000ASPC..214..701I }} *{{citation | postscript=. | title=Circumstellar Matter in the Interacting Binary CX Draconis | last1=Koubský | first1=P. | last2=Richards | first2=M. T. | last3=Šimon | first3=V. | work=Proceedings of the 29th Conference on Variable Star Research. 7th - 9th November 1997. Brno, Czech Republic | editor1-first=J. | editor1-last=Dusek | editor2-first=M. | editor2-last=Zejda | isbn=80-85882-09-4 | page=64 | date=February 1998 | bibcode=1998stel.conf...64K }} *{{citation | postscript=. | title=Spectroscopy and Photometry of the Interacting Binary CX Draconis - Evidence for Circumstellar Mater | last1=Koubsky | first1=P. | last2=Harmanec | first2=P. | last3=Bozic | first3=H. | last4=Rercy | first4=J. R. | last5=Ziznovsky | first5=J. | last6=Huang | first6=L. | last7=Richards | first7=M. T. | last8=Hadrava | first8=P. | last9=Simon | first9=V. | journal=Hvar Observatory Bulletin | volume=22 | issue=1 | pages=17–36 | year=1998 | bibcode=1998HvaOB..22...17K }} *{{citation | postscript=. | title=The interacting binary CX Draconis: new orbital elements and evidence for mass transfer. | last=Simon | first=V. | journal=Astronomy and Astrophysics | volume=308 | pages=799–808 | date=April 1996 | bibcode=1996A&A...308..799S }} *{{citation | postscript=. | title=Interacting Binary CX Draconis | last1=Koubský | first1=P. | last2=Horn | first2=J. | last3=Harmanec | first3=P. | last4=Peters | first4=G. J. | last5=Polidan | first5=R. S. | editor1-last=İbanoğlu | editor1-first=C | work=Active Close Binaries | series=NATO ASI Series | volume=319 | year=1990 | pages=237–238 | publisher=Springer | location=Dordrecht | doi=10.1007/978-94-009-0679-2_18 | isbn=978-94-010-6790-4 }} *{{citation | postscript=. | title=Photometric observations of the emission B star CX Dra (HD 174237) | last1=Magalashvili | first1=N. L. | last2=Kumsishvili | first2=Ya. I. | journal=Byulleten Abastumanskaya Astrofizicheskaya Observatoriya | volume=61 | pages=79–82 | year=1986 | bibcode=1986AbaOB..61...79M }} *{{citation | postscript=. | title=Call for Systematic Photoelectric Observations of CX Dra | last1=Harmanec | first1=P. | last2=Horn | first2=J. | last3=Koubsky | first3=P. | last4=Ziznovsky | first4=J. | journal=Information Bulletin on Variable Stars | volume=1931 | page=1 | date=March 1981 | bibcode=1981IBVS.1931....1H }} *{{citation | postscript=. | title=Properties and Nature of Be and Shell Stars. 10. Light and Colour Variations of CX Dra | last1=Koubský | first1=P. | last2=Harmanec | first2=P. | last3=Horn | first3=J. | last4=Jerzykiewicz | first4=M. | last5=Papoušek | first5=J. | last6=Kříž | first6=S. | last7=Pavlovski | first7=K. | last8=Ždárský | first8=F. | journal=Bulletin of the Astronomical Institute of Czechoslovakia | volume=31 | issue=2 | pages=75–84 | year=1980 | bibcode=1980BAICz..31...75K }} *{{citation | postscript=. | title=UBV photometry of CX Cra. Search for rapid variations | last1=Koubský | first1=P. | last2=Harmanec | first2=P. | last3=Horn | first3=J. | last4=Jerzykiewicz | first4=M. | last5=Kríz | first5=S. | last6=Pavlovski | first6=K. | last7=Zdárský | first7=F. | journal=Acta Universitatis Carolinae, Mathematica et Physica | volume=21 | issue=2 | pages=33–54 | year=1980 | url=https://dml.cz/bitstream/handle/10338.dmlcz/142453/ActaCarolinae_021-1980-2_6.pdf | access-date=2023-02-15 | bibcode=1980AcMPh..21...33K }} {{Div col end}}

{{Stars of Draco}}  [[Category:Be stars]] [[Category:F-type giants]] [[Category:Spectroscopic binaries]] [[Category:Gamma Cassiopeiae variable stars]] [[Category:Rotating ellipsoidal variables]]  [[Category:Draco (constellation)]] [[Category:Bright Star Catalogue objects|7084]] [[Category:Durchmusterung objects|BD+52 2280]] [[Category:Henry Draper Catalogue objects|174237]] [[Category:Hipparcos objects|092133]] [[Category:Objects with variable star designations|Draconis, CX]]