Editing Wild Duck Cluster (section)

{{Short description|Open cluster in the constellation Scutum}}
{{Infobox open cluster
 | image=[[File:Eso1430a.jpg|300px]]
 | caption= Open cluster Messier 11 in Scutum
 | name  = Wild Duck Cluster
 | epoch = J2000.0
 | class = I,2,r
 | constellation = [[Scutum (constellation)|Scutum]]
 | ra  = {{RA|18|51|05.0}}<ref name=Wu2009/>
 | dec = {{Dec|-06|16|12}}<ref name=Wu2009/>
 | dist_ly   = {{Convert|1877|pc|ly|order=flip|lk=on}}<ref name=kharchenko2005/>
 | dist_pc   = 
 | appmag_v  = 5.8<ref name=OMeara1998/>
 | size_v    = {{Val|22.8|ul=arcminute}}<ref name=kharchenko2005/>
 | mass_msol = 11,000<ref name=Santos2005/>
 | radius_ly = {{Convert|29|pc|ly|disp=out}}<ref name=Santos2005/>
 | v_hb  = 
 | age   = {{Val|316|50|u=million years}}<ref name=Casamiquela2018/>
 | notes = 
 | names = [[Messier Catalog|Messier]] 11, [[New General Catalogue|NGC]] 6705, [[Collinder catalog|Cr]] 391, [[Melotte catalogue|Mel]] 213, OCl 76.0<ref name=SIMBAD/>
}}

The '''Wild Duck Cluster''' (also known as '''Messier 11''', or '''NGC 6705''') is an [[open cluster]] of stars in the [[constellation]] [[Scutum (constellation)|Scutum]] (the Shield). It was discovered by [[Gottfried Kirch]] in 1681.<ref name=OMeara1998/> [[Charles Messier]] included it in his catalogue of diffuse objects in 1764. Its popular name derives from the brighter stars forming a triangle which could resemble a flying flock of [[duck]]s<ref name=OMeara1998/> (or, from other angles, one swimming duck). The cluster is located just to the east of the Scutum Star Cloud midpoint.<ref name=Crossen2012/>

The Wild Duck Cluster is one of the richest and most compact of the known open clusters. It is one of the most massive open clusters known, and it has been extensively studied. Its age has been estimated to about 316 million years.<ref name=Casamiquela2018/> The core radius is {{cvt|1.23|pc|ly}} while the [[Globular_cluster#Radii|tidal radius]] is {{cvt|29|pc|ly}}. Estimates for the cluster's mass range from {{Val|3700|ul=solar mass|fmt=commas}}<ref name=Gaudin2014/> to {{Val|11000|u=solar mass|fmt=commas}},<ref name=Santos2005/> depending on the method chosen. The brightest cluster member is visual magnitude 8, and it has 870 members of at least magnitude 16.5. It has an integrated [[absolute magnitude]] of –6.5, and a visual [[extinction (astronomy)|extinction]] of 1.3.<ref name=Crossen2012/>

The cluster is [[metallicity|metal-rich]] with an iron abundance of [Fe/H] = {{Val|0.17|0.04}}. Despite its youth, it shows an enhancement of [[alpha process]] elements. Possibly this is due to an enhancement of its birth [[molecular cloud]] by a nearby [[Type II supernova]] explosion.<ref name=Casamiquela2018/> At least nine [[variable star]] members have been identified with high probability, plus 29 lower probability members. The former include two [[eclipsing binary]] star systems.<ref name=Messina2010/> The cluster is located {{cvt|6.8|kpc|ly}} from the [[Galactic Center]], close to the [[galactic plane]], and is not far from its birthplace.<ref name=Casamiquela2018/>