{{Short description|Variable star in the constellation Draco}} {{Starbox begin}} {{Starbox image | image = {{Location mark |image=Draco constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=4 Draconis |x=898|y=402 }} | caption = Location of 4 Draconis (circled in red) }} {{Starbox observe | epoch = [[J2000.0]] | ra = {{RA|12|30|06.66200}}<ref name=dr3/> | dec = {{DEC|+69|12|03.9742}}<ref name=dr3/> | appmag_v = 4.90 - 5.12<ref name="IVSI"/> | constell = [[Draco (constellation)|Draco]] }} {{Starbox character | type = [[asymptotic giant branch|AGB]] + ?<ref name=ortiz2016/> | class = M3+ IIIa<ref name=perkins/> | b-v = | u-b = | variable = Z Andromedae<ref name="IVSI"/> }} {{Starbox astrometry | radial_v = −15<ref name="Famaey2009"/> | prop_mo_ra = {{val|-57.311}}<ref name=dr3/> | prop_mo_dec = {{val|-50.365}}<ref name=dr3/> | parallax = 5.7233 | p_error = 0.1880 | parallax_footnote = <ref name=dr3/> | absmag_v = −1.37<ref name=xhip/> }} {{Starbox orbit | reference = <ref name="Reimers1988"/> | primary = 4 Draconis A (red giant) | name = 4 Draconis B | period = | period_unitless = {{val|fmt=commas|1703|3|ul=d}} | axis = | axis_unitless = {{val|82|4|ul=Gm}} ( a⋅sin(i) ) | eccentricity = {{val|0.30|0.05}} | inclination = | node = | periastron = 2442868.5 | periarg = | periarg_primary = {{val|244|9}} | k1 = {{val|3.67|0.19}} | k2 = }} {{Starbox detail | component1 = red giant | mass = {{val|1.64|0.2}}<ref name=baines/> | radius = {{val|111.0|9.30|11.2}}<ref name=baines/> | temperature = {{val|3718|69|fmt=commas}}<ref name=baines/> | gravity = 1.24<ref name=baines/> | luminosity = {{val|2122|419|fmt=commas}}<ref name=baines/> | age_gyr={{val|1.97|0.57}}<ref name=baines/> | component2 = white dwarf | mass2 = ~0.8<ref name="Sion2017"/> | radius2 = 0.0094<ref name="Sion2017"/> | luminosity2 = {{Val|6.6|-|22|e=-3}}<ref name="Sion2017"/> | gravity2 = 8.4<ref name="Sion2017"/> | temperature2 = {{val|fmt=commas|20000|3000}}<ref name="Sion2017"/> }} {{Starbox catalog | names = [[variable star designation|CQ Dra]], [[Henry Draper Catalogue|HD]] 108907, [[Star catalogue#BS, BSC, HR|HR]] 4765, [[Hipparcos catalogue|HIP]] 60998, [[Star catalogue#SAO|SAO]] 15816<ref name=SIMBAD/> }} {{Starbox reference | Simbad = CQ+Dra }} {{Starbox end}}
'''4 Draconis''', also known as '''HR 4765''' and '''CQ Draconis''', is a star about 570 [[light year]]s from the Earth, in the constellation [[Draco (constellation)|Draco]].<ref name=dr3/> It is a 5th [[apparent magnitude|magnitude]] star, so it will be faintly visible to the [[naked eye]] of an observer far from [[light pollution|city lights]].<ref name=dr3/> It is a variable star, whose brightness varies slightly from 4.90 to 5.12 over a period of 4.66 years.<ref name="IVSI"/>
[[File:CQDraLightCurve.png|thumb|left|[[Light curve]]s for CQ Draconis, adapted from Skopal ''et al.'' (1992)<ref name="Skopal1992"/> The brightening seen (most clearly in the ultraviolet) after June 1990 occurred shortly after the [[apsis|periastron]] passage.<ref name="Hric1991"/>]] In 1967, Olin Eggen discovered that 4 Draconis is a variable star, during a multicolor [[photometry (astronomy)|photometric]] survey of red stars.<ref name="Eggen1967"/> In 1973 it was given the [[variable star designation]] CQ Draconis.<ref name="Kukarkin1973"/>
Until the year 1985, 4 Draconis was thought to be a normal [[red giant]] star. In 1985, Dieter Reimers announced that the [[International Ultraviolet Explorer]] had detected a hot companion to the red giant, which itself appeared to be a binary [[cataclysmic variable star]], making the complete system a triple star.<ref name="Reimers1985"/> However a 2003 study by Peter Wheatley ''et al.'', who examined [[ROSAT]] [[X-ray]] data for the star, concluded that the hot companion was more apt to be a single [[white dwarf]], rather than a binary, and that the white dwarf is accreting material from the red giant.<ref name="Wheatley2003"/> There does not yet appear to be a consensus about the multiplicity; some later studies consider 4 Draconis to be a binary,<ref name="Skopal2005"/><ref name="Nuñez2016"/> and some a triple.<ref name="DiStefano2020"/><ref name="Sion2017"/>
In 1987, Alexander Brown announced that 6 cm wavelength [[radio]] emission had been detected by the [[Very Large Array]]. The strength of the radio emission was variable on a timescale of weeks to months.<ref name="Brown1987"/>
It is possible that an outburst of 4 Draconis was the "[[guest star (astronomy)|guest star]]" reported by Chinese astronomers in the year 369 CE, in the constellation Zigong.<ref name="Hoffmann2020"/>
==References== {{Reflist|30em|refs=
<ref name=perkins>{{cite journal | title=The Perkins catalog of revised MK types for the cooler stars | last1=Keenan | first1=Philip C. | last2=McNeil | first2=Raymond C. | journal=The Astrophysical Journal Supplement Series | volume=71 | pages=245 | year=1989 | bibcode=1989ApJS...71..245K | doi=10.1086/191373 }}</ref>
<ref name=baines>{{cite journal |last1=Baines | first1= Ellyn K.|last2=Armstrong| first2= J. Thomas|last3=Schmitt| first3=Henrique R.|last4= Zavala| first4= R. T.|last5= Benson| first5= James A.|last6= Hutter| first6= Donald J.|last7=Tycner| first7= Christopher |last8=van Belle| first8= Gerard T. |title=Fundamental parameters of 87 stars from the Navy Precision Optical Interferometer |journal=The Astronomical Journal |date=2017 |volume=155 |issue=1 |pages=16 |doi=10.3847/1538-3881/aa9d8b | bibcode= 2018AJ....155...30B | arxiv=1712.08109 | s2cid= 119427037| doi-access= free}}</ref>
<ref name=xhip>{{cite journal | title=XHIP: An extended hipparcos compilation | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | journal=Astronomy Letters | volume=38 | issue=5 | pages=331 | year=2012 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | arxiv=1108.4971 | s2cid=119257644 }}</ref>
<ref name="Skopal1992">{{cite journal | last1=Skopal | first1=A. | last2=Hric | first2=L. | last3=Urban | first3=Z. | last4=Pigulski | first4=A. | last5=Blanco | first5=C. | last6=Papousek | first6=J. | last7=Hanzl | first7=D. | last8=Agerer | first8=F. | last9=Niarchos | first9=P. | last10=Rovithis-Livaniou | first10=H. | last11=Rovithis | first11=P. | last12=Tsvetkova | first12=K. | last13=Semkov | first13=E. | last14=Velic | first14=Z. | last15=Michalek | first15=F. | last16=Komacka | first16=L. | last17=Schweitzer | first17=E. | last18=Korth | first18=S. | title=Photometry of symbiotic stars - an international campaign. III. Z And, EG And, R Aqr, UV Aur, TX CVn, T CrB, BF Cyg, CH Cyg, CI Cyg, V 1016 Cyg, V 1329 Cyg, AG Dra, CQ DRA (4 Dra), YY Her, V 443 Her, SS Lep, RS Oph, AG Peg, AX Per, HM Sge, FG Ser (AS 296), PU Vul | journal=Contributions of the Astronomical Observatory Skalnate Pleso | date=July 1992 | volume=22 | pages=131–172 | bibcode=1992CoSka..22..131S }}</ref>
<ref name=dr3>{{cite Gaia DR3|1683014206596170240}}</ref>
<ref name=SIMBAD>{{cite simbad | title= 4 Dra -- Spectroscopic Binary | access-date=2023-02-26}}</ref>
<ref name="IVSI">{{cite web | title=CQ Dra | url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=13789 | website=The International Variable Star Index | publisher=AAVSO | access-date=26 February 2023}}</ref>
<ref name="Hoffmann2020">{{cite journal |last1=Hoffmann | first1=Susanne M. | last2=Vogt | first2=Nikolaus | title=A search for the modern counterparts of the Far Eastern guest stars 369 CE, 386 CE and 393 CE | journal=Monthly Notices of the Royal Astronomical Society | date=September 2020 | volume=497 | issue=2 | pages=1419–1433 | doi=10.1093/mnras/staa1970 | doi-access=free | arxiv=2007.01013 | bibcode=2020MNRAS.497.1419H }}</ref>
<ref name="Eggen1967">{{cite journal | last1=Eggen | first1=O. J. | title=Narrow and broad band photometry of red stars : I. Northern giants | journal=Astrophysical Journal Supplement Series | date=September 1967 | volume=14 | pages=307–358 | doi=10.1086/190158 | bibcode=1967ApJS...14..307E | doi-access=free }}</ref>
<ref name="Kukarkin1973">{{cite journal | last1=Kukarkin | first1=B. V. | last2=Kholopov | first2=P. N. | last3=Kukarkina | first3=N. P. | last4=Perova | first4=N. B. | title=59th Name-List of Variable Stars | bibcode=1973IBVS..834....1K | journal=Information Bulletin on Variable Stars | date=October 1973 | volume=834 | page=1 | url=https://ibvs.konkoly.hu/pub/ibvs/0801/0834.pdf | access-date=27 February 2023}}</ref>
<ref name="Reimers1985">{{cite journal | last1=Reimers | first1=D. | title=Discovery of a cataclysmic variable type companion of the M3 III giant 4 DRA with IUE | journal=Astronomy and Astrophysics | date=January 1985 | volume=142 | pages=L16–L18 | bibcode=1985A&A...142L..16R }}</ref>
<ref name="Famaey2009">{{cite journal | last1=Famaey | first1=B. | last2=Pourbaix | first2=D. | last3=Frankowski | first3=A. | last4=van Eck | first4=S. | last5=Mayor | first5=M. | last6=Udry | first6=S. | last7=Jorissen | first7=A. | title=Spectroscopic binaries among Hipparcos M giants,. I. Data, orbits, and intrinsic variations | journal=Astronomy and Astrophysics | date=May 2009 | volume=498 | issue=2 | pages=627–640 | doi=10.1051/0004-6361/200810698 | arxiv=0901.0934 | doi-access=free | bibcode=2009A&A...498..627F}}</ref>
<ref name="Brown1987">{{cite journal | last1=Brown | first1=Alexander | title=Variable Radio Emission from the 4 Draconis System | journal=Astrophysical Journal Letters | date=January 1987 | volume=312 | pages=L51–L53 | doi=10.1086/184818 | bibcode=1987ApJ...312L..51B }}</ref>
<ref name="Wheatley2003">{{cite journal | last1=Wheatley | first1=Peter J. | last2=Mukai | first2=Koji | last3=de Martino | first3=Domitilla | title=X-ray observations of 4 Draconis: symbiotic binary or cataclysmic triple? | journal=Monthly Notices of the Royal Astronomical Society | date=December 2003 | volume=346 | issue=3 | pages=855–860 | doi=10.1111/j.1365-2966.2003.07149.x | arxiv=astro-ph/0309410 | bibcode=2003MNRAS.346..855W | doi-access=free }}</ref>
<ref name="Hric1991">{{cite journal | last1=Hric | first1=L. | last2=Urban | first2=Z. | bibcode=1991IBVS.3683....1H | title=The Symbiotic-Like/Cataclysmic Triple System 4 Dra (= CQ Dra): Detection of a Post-Periastron Passage Brightening | journal=Information Bulletin on Variable Stars | date=November 1991 | volume=3683 | page=1 | url=https://ibvs.konkoly.hu/pub/ibvs/3601/3683.pdf | access-date=28 February 2023}}</ref>
<ref name="Reimers1988">{{cite journal | last1=Reimers | first1=D. | last2=Griffin | first2=R. F. | last3=Brown | first3=A. | title=4 Draconis : a unique triple system containing an M3 giant and a cataclysmic binary | journal=Astronomy and Astrophysics | date=March 1988 | volume=193 | pages=180–184 | bibcode=1988A&A...193..180R }}</ref>
<ref name="DiStefano2020">{{cite journal | last1=Di Stefano | first1=R. | title=Mass from a third star: transformations of close compact-object binaries within hierarchical triples | journal=Monthly Notices of the Royal Astronomical Society | date=April 2020 | volume=493 | issue=2 | pages=1855–1873 | doi=10.1093/mnras/staa220 | doi-access=free | bibcode=2020MNRAS.493.1855D | arxiv=1805.09338}}</ref>
<ref name="Sion2017">{{cite journal | last1=Sion | first1=Edward M. | last2=Godon | first2=Patrick | last3=Mikolajewska | first3=Joanna | last4=Sabra | first4=Bassem | last5=Kolobow | first5=Craig | title=FUSE Spectroscopy of the Accreting Hot Components in Symbiotic Variables | journal=The Astronomical Journal | date=April 2017 | volume=153 | issue=4 | page=160 | doi=10.3847/1538-3881/aa62a9 | pmid=29456255 | pmc=5810147 | arxiv=1702.07341 | bibcode=2017AJ....153..160S | doi-access=free }}</ref>
<ref name="Skopal2005">{{cite journal | last1=Skopal | first1=A. | title=Accretion-powered symbiotic binaries: EG And and CQ Dra | journal=The Astrophysics of Cataclysmic Variables and Related Objects, Proceedings of ASP Conference | date=August 2005 | volume=330 | pages=463–464 | bibcode=2005ASPC..330..463S | url=http://aspbooks.org/publications/330/463.pdf | access-date=28 February 2023}}</ref>
<ref name="Nuñez2016">{{cite journal | last1=Nuñez | first1=N. E. | last2=Nelson | first2=T. | last3=Mukai | first3=K. | last4=Sokoloski | first4=J. L. | last5=Luna | first5=G. J. M. | title=Symbiotic Stars in X-Rays. III. Suzaku Observations | journal=The Astrophysical Journal | date=June 2016 | volume=824 | issue=1 | page=23 | doi=10.3847/0004-637X/824/1/23 | arxiv=1604.05980 | bibcode=2016ApJ...824...23N | doi-access=free }}</ref>
<ref name=ortiz2016>{{cite journal |bibcode=2016MNRAS.461.3036O |title=Ultraviolet emission from main-sequence companions of AGB stars |last1=Ortiz |first1=Roberto |last2=Guerrero |first2=Martín A. |journal=Monthly Notices of the Royal Astronomical Society |date=2016 |volume=461 |issue=3 |page=3036 |doi=10.1093/mnras/stw1547 |doi-access=free |arxiv=1606.09086 }}</ref>
}}
{{Stars of Draco}}
[[Category:Draco (constellation)]] [[Category:Hipparcos objects|060998]] [[Category:Henry Draper Catalogue objects|108907]] [[Category:Objects with variable star designations|Draconis, CQ]] [[Category:Z Andromedae variables]] [[Category:Flamsteed objects|Draconis, 4]] [[Category:M-type giants]] [[Category:Asymptotic-giant-branch stars]] [[Category:White dwarfs]]