View source for Coma Star Cluster

{{Short description|Open cluster in the constellation Coma Berenices}}
{{Distinguish|Coma Cluster}}
{{Infobox open cluster|
| name = Coma Star Cluster
| image = ASY-MB0124-Coma-Star-Cluster.jpg
| image_size = 300px
| caption= Coma Star Cluster, Mel 111
| epoch = [[J2000]]
| class = 
| constellation = [[Coma Berenices]]
| ra = {{RA|12|22.5}}<ref name="simbad">{{cite web |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Melotte+111 |title=Cl Melotte 111 -- Open (galactic) Cluster |work=[[SIMBAD]] |access-date=23 October 2013}}</ref>
| dec = {{DEC|+25|51}}<ref name="simbad" />
| dist_ly = 280 ly
| dist_pc = 86 pc<ref name=vanleeuwen09/><ref name=majaess11/>
| appmag_v = +1.8
| size_v = 7.5° <ref name=vanleeuwen09/>
| mass_kg = -
| mass_msol = -
| radius_ly = -
| v_hb = -
| age = -
| notes = Second closest [[open cluster]]{{cn|date=June 2020}}
| names = Coma Ber Cluster,<ref name="simbad" /> [[Collinder catalogue|Cr]] 256,<ref name="sandt-clusters">{{cite web |url=http://www.skyandtelescope.com/observing/objects/deepsky/3304896.html?page=8 |archive-url=https://archive.today/20131023150227/http://www.skyandtelescope.com/observing/objects/deepsky/3304896.html?page=8 |url-status=dead |archive-date=October 23, 2013 |title=Open Clusters by the Season |work=Sky & Telescope |first=Walter Scott |last=Houston |page=8 |access-date=23 October 2013 }}</ref> [[Philibert Jacques Melotte|Mel]] 111,<ref name="simbad" /> OCl 558.0<ref name="simbad" /> 
}}

The '''Coma Star Cluster''' (also known as '''Melotte 111''' or '''Collinder 256''') is a nearby [[open cluster]] located in the constellation [[Coma Berenices]]. The cluster contains about 40 brighter stars (between magnitudes 5 and 10) with a [[common proper motion]]. The brighter stars of the cluster make out a distinctive "V" shape as seen when Coma Berenices is rising. The cluster used to represent the tail of [[Leo (constellation)|Leo]]. However, in around 240 BC, [[Ptolemy III]] renamed it for the Egyptian queen Berenice's legendary sacrifice of her hair.

The ''[[Hipparcos]]'' satellite and infrared [[color-magnitude diagram]] fitting have been used to establish a distance to the cluster's center of approximately {{convert|86|pc}}.<ref name=vanleeuwen09>{{cite journal |title=Parallaxes and proper motions for 20 open clusters as based on the new Hipparcos catalogue |journal=Astronomy and Astrophysics |first=F. |last=van Leeuwen |volume=497 |issue=1 |pages=209–242 |date=April 2009 |bibcode=2009A&A...497..209V |doi=10.1051/0004-6361/200811382|arxiv = 0902.1039 |s2cid=16420237 }}</ref><ref name=majaess11>{{cite journal |title=Deep Infrared ZAMS Fits to Benchmark Open Clusters Hosting Delta Scuti Stars |journal=Journal of the American Association of Variable Star Observers |first1=D. |last1=Majaess |first2=D. |last2=Turner |first3=D. |last3=Lane |first4=T. |last4=Krajci |volume=39 |issue=2 |page=219 |date=September 2011 |bibcode=2011JAVSO..39..219M |arxiv=1102.1705}}</ref> The distance established via the independent analyses agree, thereby making the cluster an important rung on the [[cosmic distance ladder]]. The open cluster is roughly twice as distant as the [[Hyades (star cluster)|Hyades]] and covers an area of more than 7.5 degrees on the sky.<ref name=vanleeuwen09/><ref name=majaess11/> The cluster is approximately 450 million years old.
[[File:Galaxymap.com, map 100 parsecs (2022).png|center|thumb|450x450px|Map of stars and [[Open cluster|open clusters]] within 100 parsecs of the Sun. The Ursa moving group is near the center at 225° [[Galactic coordinate system|galactic longitude]].]]
{| class="wikitable" style="text-align:center;"
|+ Brightest&nbsp;members<br>{{nowrap|(m<sub>v</sub> < 6.5)<ref name=tang2018>{{cite journal |bibcode=2018ApJ...862..106T |title=Characterization of Stellar and Substellar Members in the Coma Berenices Star Cluster |journal=The Astrophysical Journal |volume=862 |issue=2 |pages=106 |last1=Tang |first1=Shih-Yun |last2=Chen |first2=W. P. |last3=Chiang |first3=P. S. |last4=Jose |first4=Jessy |last5=Herczeg |first5=Gregory J. |last6=Goldman |first6=Bertrand |year=2018 |arxiv=1806.08322 |doi=10.3847/1538-4357/aacb7a |s2cid=119416393 |doi-access=free }}</ref>
}}
! Identifier
! Magnitude
|-
| [[Gamma Comae Berenices|γ Com]]{{efn|Outside a nominal 5° radius adopted as the cluster size}}
| 4.81
|-
| [[12 Comae Berenices|12 Com]]
| 4.81
|-
| [[31 Comae Berenices|31 Com]]
| 4.94
|-
| [[14 Comae Berenices|14 Com]]
| 4.95
|-
| [[16 Comae Berenices|16 Com]]
| 4.96
|-
| [[13 Comae Berenices|13 Com]]
| 5.18
|-
| [[17 Comae Berenices|17 Com]]
| 5.24
|-
| [[21 Comae Berenices|21 Com]]
| 5.44
|-
| [[18 Comae Berenices|18 Com]]{{efn|At the same distance as Melotte 111, but its proper motion and isochrone are inconsistent.}}
| 5.47
|-
| [[HD 106887]]
| 5.71
|-
| [[HD 105805]]
| 5.99
|-
| [[8 Comae Berenices|8 Com]]
| 6.22
|-
| [[22 Comae Berenices|22 Com]]
| 6.24
|-
| [[FM Comae Berenices|FM Com]]
| 6.43
|}
{{notelist}}

== See also ==
* [[Alpha Persei Cluster]]
* [[List of nearby stellar associations and moving groups]]

== References ==
{{reflist}}

== External links ==
* {{commons category-inline|Melotte 111}}
* [http://webda.physics.muni.cz/cgi-bin/ocl_page.cgi?cluster=Mel111 WEBDA page for open cluster Coma Ber] by [[Masaryk University]]
* [http://messier.seds.org/xtra/ngc/mel111.html SEDS] – Melotte 111

{{Coma Berenices|state=collapsed}}
{{Sky|12|22|30|+|25|51|00|288}}
{{star-cluster-stub}}

{{DEFAULTSORT:Coma Star Cluster}}
[[Category:Open clusters]]
[[Category:Coma Berenices]]
[[Category:Astronomical objects known since antiquity]]