View source for IC 4665

{{Short description|Open cluster in the constellation Opiuchus}}
{{Infobox open cluster
 | image     = File:IC 4665.png
 | caption   = Cluster IC 4665 with star [[Beta Ophiuchi]] below
 | name      = IC 4665
 | epoch     = [[J2000]]
 | ra        = {{RA|17|46|13.0}}<ref name=Tarricq_et_al_2021/>
 | dec       = {{DEC|+05|36|54}}<ref name=Tarricq_et_al_2021/>
 | dist_ly   = 1.12 [[Light-year#Distances in light-years|kly]]
 | dist_pc   = 343.6&nbsp;[[Parsec|pc]]<ref name=Jeffries_et_al_2023/>
 | appmag_v  = 4.2<ref name=Crossen_Rhemann_2012/>
 | size_v    = {{val|40|×|40|u=arcminute}}<ref name=Crossen_Rhemann_2012/>
 | constellation  = [[Ophiuchus]]
 | radius_ly = 33.59<ref>{{cite journal | last1=Abt | first1=Helmut A. | last2=Snowden | first2=Michael S. | title=The Galactic Cluster IC 4665 | journal=The Astrophysical Journal | date=1964 | volume=139 | page=1139 | doi=10.1086/147856 | bibcode=1964ApJ...139.1139A | url=https://articles.adsabs.harvard.edu//full/1964ApJ...139.1139A/0001146.000.html }}</ref>
 | absmag_v  = 
 | notes     = 
 | age       = {{val|55|3}}&nbsp;Myr<ref name=Jeffries_et_al_2023/>
 | names     = [[Collinder catalogue|Cr]] 349, [[Melotte catalogue|Mel]] 179<ref name="simbad" />
}}

'''IC 4665''' (Collinder 349 / Melotte 179), also known as the '''Summer Beehive Cluster'''<ref>{{cite web | title=Summer Beehive Cluster | work=Wolf Creek Observatory | date=28 June 2022 | url=https://wolfcreek.space/index.php/2022/06/28/summer-beehive-cluster/ }}</ref> or '''[[Poseidon]]'s Trident ''',<ref>{{cite web | title=Fall into Cygnus and More with September Deep-Sky Objects | url=https://www.unistellar.com/blog/observe-september-2023/ }}</ref> is an [[open cluster]] of stars in the [[constellation]] [[Ophiuchus]], about 1° to the northeast of the star [[Beta Ophiuchi]].<ref name=Crossen_Rhemann_2012/> It was discovered by Swiss astronomer [[Philippe Loys de Chéseaux]] in 1745. The cluster lies about 1,100 [[light year]]s away from [[Earth]].<ref name=Jeffries_et_al_2023/> It is easily visible in the smallest of [[telescope]]s and also with [[binoculars]].<ref name=Crossen_Rhemann_2012/> From a sufficiently dark place it is also visible to the [[naked eye]]. It is one of the brightest clusters not to be cataloged by [[Charles Messier]] or [[William Herschel]], probably because it is so loose and coarse.

Age estimates for this cluster have ranged from 20 up to as high as 100 million years. Comparison of the stellar [[Lithium depletion boundary|lithium depletion]] with other clusters suggests it began to develop about 55 million years ago.<ref name=Jeffries_et_al_2023/> The upper [[main sequence turnoff]] age is {{val|42|12}}&nbsp;Myr.<ref name=Cargile_James_2010/> 819 candidate cluster members have been identified.<ref name=Miret-Roig_et_al_2020/> Two [[chemically peculiar star]]s were found to be members in 1977.<ref name=Levato_Malaroda_1977/> It has an estimated mass of about 130 suns.

There is evidence that IC 4665 is undergoing a collision with the older cluster Collinder 350, located about 4° away. Currently they are separated by a distance of {{cvt|36.25|pc|ly|order=flip}}, after having formed at least {{cvt|500|pc|ly|order=flip}} apart. It is unclear whether the two clusters will merge as a result of the collision.<ref name=Piatti_Malhan_2022/>

== References ==
{{reflist|refs=

<ref name="simbad">{{cite simbad
 | title=IC 4665 | access-date=2007-04-17 }}</ref>

<ref name=Crossen_Rhemann_2012>{{cite book
 | title=Sky Vistas: Astronomy for Binoculars and Richest-Field Telescopes
 | first1=Craig | last1=Crossen | first2=Gerald | last2=Rhemann
 | publisher=Springer Science & Business Media
 | isbn=9783709106266 | page=60 | year=2012
 | url=https://books.google.com/books?id=3vELBwAAQBAJ&pg=PA60 }}</ref>

<ref name=Jeffries_et_al_2023>{{cite journal
 | title=A revised age greater than 50 Myr for the young cluster IC 4665
 | display-authors=1 | last1=Jeffries | first1=R. D.
 | last2=Jackson | first2=R. J. | last3=Binks | first3=A. S.
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=526 | pages=1260–1267 | date=2023
 | issue=1 | arxiv=2309.07619 | bibcode=2023MNRAS.526.1260J
 | doi=10.1093/mnras/stad2845 | doi-access=free }}</ref>

<ref name=Tarricq_et_al_2021>{{cite journal
 | title=3D kinematics and age distribution of the open cluster population
 | display-authors=1 | last1=Tarricq | first1=Y.
 | last2=Soubiran | first2=C. | last3=Casamiquela | first3=L.
 | last4=Cantat-Gaudin | first4=T. | last5=Chemin | first5=L.
 | last6=Anders | first6=F. | last7=Antoja | first7=T.
 | last8=Romero-Gómez | first8=M. | last9=Figueras | first9=F.
 | last10=Jordi | first10=C. | last11=Bragaglia | first11=A.
 | last12=Balaguer-Núñez | first12=L. | last13=Carrera | first13=R.
 | last14=Castro-Ginard | first14=A. | last15=Moitinho | first15=A.
 | last16=Ramos | first16=P. | last17=Bossini | first17=D.
 | journal=Astronomy & Astrophysics
 | volume=647 | at=id. A19 | date=March 2021
 | doi=10.1051/0004-6361/202039388 | arxiv=2012.04017
 | bibcode=2021A&A...647A..19T }}</ref>

<ref name=Piatti_Malhan_2022>{{cite journal
 | title=First evidence of a collision between two unrelated open clusters in the Milky Way
 | last1=Piatti | first1=Andrés E. | last2=Malhan | first2=Khyati
 | journal=Monthly Notices of the Royal Astronomical Society: Letters
 | volume=511 | issue=1 | pages=L1–L7 | date=March 2022
 | doi=10.1093/mnrasl/slab130 | doi-access=free | arxiv=2112.03786
 | bibcode=2022MNRAS.511L...1P }}</ref>

<ref name=Miret-Roig_et_al_2020>{{cite journal
 | title=Searching for debris discs in the 30 Myr open cluster IC 4665
 | display-authors=1 | last1=Miret-Roig | first1=N.
 | last2=Huélamo | first2=N. | last3=Bouy | first3=H.
 | journal=Astronomy & Astrophysics
 | volume=641 | at=id. A156 | date=September 2020
 | doi=10.1051/0004-6361/202038205 | arxiv=2007.04992
 | bibcode=2020A&A...641A.156M }}</ref>

<ref name=Cargile_James_2010>{{cite journal
 | title=Employing a New, BVI<sub>c</sub> Photometric Survey of IC 4665 to Investigate the Age of This Young Open Cluster
 | last1=Cargile | first1=P. A. | last2=James | first2=D. J.
 | journal=The Astronomical Journal
 | volume=140 | issue=3 | pages=677–691 | date=September 2010
 | doi=10.1088/0004-6256/140/3/677 | arxiv=1005.3329
 | bibcode=2010AJ....140..677C }}</ref>

<ref name=Levato_Malaroda_1977>{{cite journal
 | title=Spectroscopic study of two peculiar stars in IC 4665 : HD 161480 and HD 161733
 | last1=Levato | first1=H. | last2=Malaroda | first2=S.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=89 | pages=84–94 | date=February 1977
 | doi=10.1086/130078 | bibcode=1977PASP...89...84L }}</ref>

}}

== External links ==
* {{commonscat-inline}}
* [http://messier.seds.org/xtra/ngc/i4665.html IC 4665 @ SEDS IC objects pages]
* [http://www.univie.ac.at/webda/cgi-bin/ocl_page.cgi?cluster=IC+4665 IC 4665 www.univie.ac.at]
* {{WikiSky}}
* [https://purl.fdlp.gov/GPO/gpo42005 X-Ray Activity in the Open Cluster IC 4665] [[National Aeronautics and Space Administration]]

{{Ophiuchus}}
{{Sky|17|46|18|+|05|43|00|1400}}

[[Category:IC objects|4665]]
[[Category:Open clusters]]
[[Category:Ophiuchus]]