View source for Winnecke 4

{{Short description|Optical double star in the constellation Ursa Major}}
{{starbox begin}}
{{Starbox image
| image=[[File:M40 (Winnecke 4) (noao-m40).jpg|280px]]
| caption=Winnecke 4 double star
}}
{{Starbox observe 2s
| epoch = J2000.0
| constell = [[Ursa Major]]<ref name=constellation/>
| component1 = A
| ra1 = {{RA|12|22|12.5272}}<ref name=edr3a/>
| dec1 = {{DEC|+58|4|58.549}}<ref name=edr3a/>
| appmag_v1 = 9.64<ref name=tycho2/>
| component2 = B
| ra2 = {{RA|12|22|18.9992}}<ref name=edr3b/>
| dec2 = {{DEC|+58|5|10.366}}<ref name=edr3b/>
| appmag_v2 = 10.11<ref name=tycho2/>
}}
{{Starbox character 
| component1 = A
| class = K0 III<ref name=nugent/>
| b-v =
| u-b =
| variable =
| component2 = B
| class2 = G0 V<ref name=nugent/>
| b-v2 =
| u-b2 =
| variable2 =
}} 
{{Starbox astrometry
| component1 = A
| parallax = 3.2191
| p_error = 0.0118
| parallax_footnote = <ref name=edr3a/>
| absmag_v = +0.88<ref name=nugent/>
| component2 = B
| parallax2 = 6.9328
| p_error2 = 0.0155
| parallax_footnote2 = <ref name=edr3b/>
| absmag_v2 = +4.0<ref name=nugent/>
}}
{{Starbox detail
| component1 = A
| mass = 1.15<ref name=starhorse/>
| luminosity = 13<ref name=dr2a/>
| radius = 4.48<ref name=dr2a/>
| temperature = 4,957<ref name=starhorse/>
| gravity = 3.16<ref name=starhorse/>
| metal_fe = −0.164<ref name=sit2020/>
| age_gyr = 4.1<ref name=sit2020/>
| component2 = B
| mass2 = 1.00<ref name=starhorse/>
| luminosity2 = 1.56<ref name=ticv8/>
| radius2 = 1.1<ref name=ticv8/>
| temperature2 = 6,146<ref name=starhorse/>
| gravity2 = 4.36<ref name=starhorse/>
| metal2_fe = −0.26<ref name=starhorse/>
}}
{{Starbox catalog
| names = [[Messier object|M]]40, [[Winnecke Catalogue of Double Stars|WNC]]&nbsp;4, {{odlist|BD=+56 1372|CCDM=12223+5805|WDS=J12222+5805}}
| component1 = A
| names1 = {{odlist|HD=238107|SAO=28353}}
| component2 = B
| names2 = {{odlist|HD=238108|SAO=28355}}
}}
{{Starbox reference
| Simbad = M40
| Simbad2 = HD+238107 |sn2=A
| Simbad3 = HD+238108 |sn3=B
}}
{{Starbox end}}

'''Winnecke 4''' (also known as '''Messier 40''' or '''WNC 4''') is an [[optical double star]] consisting of two unrelated stars in a northerly zone of the sky, [[Ursa Major]].

The pair were discovered by [[Charles Messier]] in 1764 while he was searching for a nebula that had been reported in the area by [[Johannes Hevelius]].  Not seeing any nebulae, Messier catalogued this apparent pair instead.  The pair were rediscovered by [[Friedrich August Theodor Winnecke]] in 1863, and included in the [[Winnecke Catalogue of Double Stars]] as number 4.  [[Robert Burnham Jr.|Burnham]] calls M40 "one of the few real mistakes in the [[Messier catalog]]," faulting Messier for including it when all he saw was a double star, not a nebula of any sort.<ref name=burnham/>

In 1991 the separation between the components was measured at 51.7[[arcsecond|″]], an increase since 1764.  Data gathered by astronomers Brian Skiff (2001) and Richard L. Nugent (2002) strongly suggested the subject was merely an [[optical double star]] rather than a physically connected (binary) system.<ref name=nugent/>  The A star that seems the brighter is over twice as far as B.<ref name=merrifield/>  Parallax measurements from the [[Gaia (spacecraft)|Gaia satellite]] show the two stars, HD 238107 and HD 238108, are at distances of {{convert|1,013|+/-|4|ly|pc|0|abbr=off|lk=on|order=flip}} and {{convert|470.2|+/-|1|ly|adj=ri0|pc|1|abbr=off|lk=on|order=flip}} respectively. HD 238108 is itself a genuine binary star, with an 18th magnitude [[white dwarf]] companion 5 arcseconds away and a parallax distance of {{convert|478.8|+/-|7.5|ly|adj=ri0|pc|1|abbr=off|lk=on|order=flip}}.{{Cn|date=November 2024}}

==See also==
* [[List of Messier objects]]

==References==
{{Reflist|refs=

<ref name=dr2a>{{cite Gaia DR2|1575047353068482688}}</ref>

<ref name=edr3a>{{cite Gaia EDR3|1575047353068482688}}</ref>

<ref name=edr3b>{{cite Gaia EDR3|1575047731026006528}}</ref>

<ref name=constellation>{{cite constellation|Winnecke 4}}</ref>

<ref name=sit2020>{{cite journal |bibcode=2020ApJ...900....4S |title=The Age Distribution of Stars in the Milky Way Bulge |last1=Sit |first1=Tawny |last2=Ness |first2=M. K. |journal=The Astrophysical Journal |year=2020 |volume=900 |issue=1 |page=4 |doi=10.3847/1538-4357/ab9ff6 |arxiv=2006.01158 |s2cid=219179385 |doi-access=free }}</ref>

<ref name=merrifield>{{cite journal|bibcode=2017Obs...137...23M|arxiv=1612.00834|title=Gaia Shows that Messier 40 is Definitely Not a Binary Star|journal=The Observatory|volume=137|pages=23|last1=Merrifield|first1=M. R|last2=Gray|first2=M. E|last3=Haran|first3=B|year=2017}}</ref>

<ref name=nugent>{{cite journal|bibcode=2002JRASC..96...63N|title=The Nature of the Double Star M40|journal=Journal of the Royal Astronomical Society of Canada|volume=96|pages=63|last1=Nugent|first1=Richard L|year=2002}}</ref>

<ref name=tycho2>{{cite journal |last1=Høg |first1=E. |last2=Fabricius |first2=C. |last3=Makarov |first3=V. V. |last4=Urban |first4=S. |last5=Corbin |first5=T. |last6=Wycoff |first6=G. |last7=Bastian |first7=U. |last8=Schwekendiek |first8=P. |last9=Wicenec |first9=A. |title=The Tycho-2 catalogue of the 2.5 million brightest stars |journal=Astronomy and Astrophysics |date=March 2000 |volume=355 |pages=L27–L30 |issn=0004-6361 |bibcode=2000A&A...355L..27H}}</ref>

<ref name=burnham>{{cite book|author=Robert Burnham|title=Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System|url=https://books.google.com/books?id=tBQoCSRdLAAC|year=1978|publisher=Courier Corporation|isbn=978-0-486-23673-5|page=1982}}</ref>

<ref name=starhorse>{{cite journal |last1=Anders |first1=F. |last2=Khalatyan |first2=A. |last3=Chiappini |first3=C. |last4=Queiroz |first4=A. B. |last5=Santiago |first5=B. X. |last6=Jordi |first6=C. |last7=Girardi |first7=L. |last8=Brown |first8=A. G. A. |last9=Matijevič |first9=G. |last10=Monari |first10=G. |last11=Cantat-Gaudin |first11=T. |last12=Weiler |first12=M. |last13=Khan |first13=S. |last14=Miglio |first14=A. |last15=Carrillo |first15=I. |last16=Romero-Gómez |first16=M. |last17=Minchev |first17=I. |last18=de Jong |first18=R. S. |last19=Antoja |first19=T. |last20=Ramos |first20=P. |last21=Steinmetz |first21=M. |last22=Enke |first22=H. |title=Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18 |journal=Astronomy & Astrophysics |date=August 2019 |volume=628 |pages=A94 |doi=10.1051/0004-6361/201935765 |issn=0004-6361 |bibcode=2019A&A...628A..94A |arxiv=1904.11302 |doi-access=free}}</ref>

<ref name=ticv8>{{Cite journal|display-authors=1|last1=Stassun|first1=Keivan G.|last2=Oelkers|first2=Ryan J.|last3=Paegert|first3=Martin|last4=Torres|first4=Guillermo|last5=Pepper|first5=Joshua|last6=De Lee|first6=Nathan|last7=Collins|first7=Kevin|last8=Latham|first8=David W.|last9=Muirhead|first9=Philip S.|last10=Chittidi|first10=Jay|last11=Rojas-Ayala|first11=Bárbara|date=2019-10-01|title=The Revised TESS Input Catalog and Candidate Target List|bibcode=2019AJ....158..138S|journal=The Astronomical Journal|volume=158|issue=4|pages=138|doi=10.3847/1538-3881/ab3467|arxiv=1905.10694 |hdl=1721.1/124721|s2cid=166227927|issn=0004-6256|hdl-access=free |doi-access=free }}</ref>

}}

==External links==
* {{commonscat-inline}}
* [http://www.messier.seds.org/m/m040.html SEDS: Messier Object 40]
* [http://www.perseus.gr/Astro-DSO-M40.htm Messier 40 CCD LRGB image with 2 hrs total exposure]
* {{cite web|title=M40 – Optical Double Star|url=http://www.deepskyvideos.com/videos/messier/M40_optical_double_star.html|work=Deep Sky Videos|publisher=[[Brady Haran]]|author=Sir Patrick Moore|author-link=Patrick Moore|author2=Mike Merrifield |author3=Pete Lawrence }}{{WikiSky|Messier 40}}

{{Portal bar|Astronomy|Stars|Outer space}}
{{Messier objects}}
{{Stars of Ursa Major}}
{{Sky|12|22|12.5||58|04|59|510}}

[[Category:Double stars]]
[[Category:Messier objects|Winnecke 4]]
[[Category:Ursa Major]]
[[Category:WNC objects|4]]
[[Category:Orion–Cygnus Arm]]
[[Category:Astronomical objects discovered in 1764|17641024]]
[[Category:Henry Draper Catalogue objects|238107/8]]
[[Category:G-type main-sequence stars]]
[[Category:K-type giants]]
[[Category:Discoveries by Charles Messier]]
[[Category:Durchmusterung objects]]