View source for Messier 50

{{short description|Open cluster in the constellation Monoceros}}
{{Use dmy dates|date=March 2021}}
{{Infobox open cluster
 | name      = [[Messier object|Messier]] 50
 | image     = [[File:M50 Open Star Cluster.png|300px]]
 | caption   = Open Messier 50 in Monoceros
 | epoch     = [[J2000]]
 | constellation = [[Monoceros (constellation)|Monoceros]]
 | ra        = {{RA|07|02|47.5}}<ref name=Frolov2012/>
 | dec       = {{Dec|−08|20|16}}<ref name=Frolov2012/>{{efn|Eight out of ninety degrees south of the [[celestial equator]]. Thus its light reaches all parts of the Earth, down to a good minimal cumulation 15° above the horizon, on the unobstructed southern horizons of the [[67th parallel north]]. This rules out Iceland and the north coasts of the two northernmost continents.}}
 | dist_ly   = {{Convert|881|pc|ly|order=flip|abbr=on|lk=on}}<ref name=kharchenko2005/>
 | appmag_v  = 5.9<ref name=Thompson2007/>
 | size_v    = {{Val|16.0|ul=arcminute}}<ref name=Thompson2007/>
 | mass_msol = > {{Val|285|ul=solar mass}}<ref name=Claria1998/>
 | radius_ly = {{convert|2.73|pc|ly|order=flip|abbr=on}}<ref name=Claria1998/>
 | age       = 158<ref name=Qin2025/>&nbsp;Myr
 | notes     = 
 | names     = M50, [[New General Catalogue|NGC]] 2323, [[Collinder catalogue|Cr]] 124, C&nbsp;0700-082, OCl&nbsp;559<ref name=SIMBAD/>
}}

'''Messier 50''' or '''M 50''', also known as '''NGC 2323''' or the '''Heart-shaped Cluster''', is an [[open cluster]] of [[star]]s in the [[constellation]] [[Monoceros (constellation)|Monoceros]]. It was recorded by [[Giovanni Domenico Cassini|G. D. Cassini]] before 1711 and independently discovered by [[Charles Messier]] in 1772{{efn|On 5 April}} while observing [[Biela's Comet]]. It is sometimes described as a 'heart-shaped' figure or a blunt arrowhead.<ref name=Thompson2007/>

M50 is about 2,900 [[light-year]]s away from [[Earth]]<ref name=kharchenko2005/> and is near to but narrowly not estimated to be gravitationally tied to the [[Canis Major]] (CMa) [[OB association|OB1 association]].<ref name=Claria1998/> It has a core radius of {{convert|1.8|pc|ly|abbr=on|order=flip}}<ref name=Sharma2008/> and spans {{convert|5.46|pc|ly|order=flip|abbr=on}}.<ref name=Claria1998/> The cluster has 508 confirmed and 109 probable members &ndash; their combined mass is more than {{Val|285|ul=solar mass}}, the mean stellar density would thus be 1.3 stars per cubic parsec.<ref name=Claria1998/> It is around 140&nbsp;million years old,<ref name=Frolov2012/> with two high-mass [[white dwarf]]s<ref name=Cummings2016/> and two [[chemically peculiar star]]s.<ref name=Paunzen2014/>

Traditionally considered to be a single star cluster, in 2025 it was found to consist of two separate sub-clusters (NGC 2323-a and NGC 2323-b), making it a binary cluster.<ref name=Qin2025>{{cite journal|doi=10.1051/0004-6361/202452962 |title=Unveiling the binary nature of NGC 2323 |date=2025 |last1=Qin |first1=Songmei |last2=Zhong |first2=Jing |last3=Tang |first3=Tong |last4=Jiang |first4=Yueyue |last5=Wang |first5=Long |last6=Wu |first6=Kai |last7=Anders |first7=Friedrich |last8=Balaguer-Núñez |first8=Lola |last9=Liu |first9=Guimei |last10=Li |first10=Chunyan |last11=Hou |first11=Jinliang |last12=Chen |first12=Li |journal=Astronomy & Astrophysics |volume=693 |pages=A317 |arxiv=2411.03787 |bibcode=2025A&A...693A.317Q }}</ref>

==Gallery==
{{Gallery|width=150
|File:M50_Mazur.jpg|Open Messier 50 in Monoceros
|File:Sirius Mirzam M41.jpg|[[Sirius]] and [[Messier 41|M41]] (lower right), M50 (upper left), and [[NGC 2360]] (lower left)
|File:Canis Major constellation map.svg|Messier 50 is found 8° north and 3° east of [[Sirius]]
}}

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

==References and footnotes==
{{reflist|refs=

<ref name=SIMBAD>{{cite simbad | title=M 50 | access-date=27 November 2018 }}</ref>

<ref name=Claria1998>{{citation
 | title=Photometric study of the open cluster NGC 2323
 | last1=Claria | first1=J. J. | last2=Piatti | first2=A. E.
 | last3=Lapasset | first3=E. | display-authors=1
 | journal=Astronomy and Astrophysics Supplement
 | volume=128 | pages=131–138 | date=February 1998
 | doi=10.1051/aas:1998130 | bibcode=1998A&AS..128..131C | doi-access=free }}</ref>

<ref name=Sharma2008>{{citation
 | title=Mass Functions and Photometric Binaries in Nine Open Clusters
 | last1=Sharma | first1=Saurabh | last2=Pandey | first2=A. K.
 | last3=Ogura | first3=K. | last4=Aoki | first4=T.
 | last5=Pandey | first5=Kavita | last6=Sandhu | first6=T. S.
 | last7=Sagar | first7=R. | display-authors=1
 | journal=The Astronomical Journal
 | volume=135 | issue=5 | pages=1934–1945 | date=May 2008
 | doi=10.1088/0004-6256/135/5/1934 | postscript=.
 | bibcode=2008AJ....135.1934S | arxiv=0803.0122 | s2cid=11895493 }}</ref>

<ref name=Paunzen2014>{{citation
 | title=Photoelectric search for peculiar stars in open clusters. XV. Feinstein 1, NGC 2168, NGC 2323, NGC 2437, NGC 2547, NGC 4103, NGC 6025, NGC 6633, Stock 2, and Trumpler 2
 | last1=Paunzen | first1=E. | last2=Netopil | first2=M.
 | last3=Maitzen | first3=H. M. | last4=Pavlovski | first4=K.
 | last5=Schnell | first5=A. | last6=Zejda | first6=M.
 | journal=Astronomy & Astrophysics | display-authors=1
 | volume=564 | id=A42 | pages=8 | date=April 2014
 | doi=10.1051/0004-6361/201423521 | postscript=.
 | bibcode=2014A&A...564A..42P | arxiv=1403.3538 | s2cid=119174151 }}</ref>

<ref name=Cummings2016>{{citation
 | title=Two Massive White Dwarfs from NGC 2323 and the Initial-Final Mass Relation for Progenitors of 4 to 6.5 M
 | last1=Cummings | first1=Jeffrey D. | last2=Kalirai | first2=Jason S.
 | last3=Tremblay | first3=P. -E. | last4=Ramirez-Ruiz | first4=Enrico
 | journal=The Astrophysical Journal | display-authors=1
 | volume=818 | issue=1 | id=84 | pages=13 | date=February 2016
 | doi=10.3847/0004-637X/818/1/84 | postscript=.
 | bibcode=2016ApJ...818...84C | arxiv=1601.03053 | s2cid=119263067 | doi-access=free }}</ref>

<ref name=Thompson2007>{{citation
 | title=Illustrated Guide to Astronomical Wonders: From Novice to Master Observer
 | first1=Robert | last1=Thompson | first2=Barbara | last2=Thompson
 | series=DIY science | publisher=O'Reilly Media, Inc.
 | year=2007 | isbn=978-0596526856 | page=321
 | url=https://books.google.com/books?id=ymt9nj_uPhwC&pg=PA321 }}</ref>

<ref name=kharchenko2005>{{Citation 
 | last1=Kharchenko | first1=N. V. | last2=Piskunov | first2=A. E.
 | last3=Röser | first3=S. | last4=Schilbach | first4=E.
 | last5=Scholz | first5=R.-D. | display-authors=1
 | title=Astrophysical parameters of Galactic open clusters
 | journal=Astronomy and Astrophysics
 | volume=438 | issue=3 | pages=1163–1173 | year=2005
 | bibcode=2005A&A...438.1163K | arxiv=astro-ph/0501674
 | doi=10.1051/0004-6361:20042523 | s2cid=9079873 | postscript=. }}</ref>

<ref name=Frolov2012>{{citation
 | title=Investigation of the open star cluster NGC 2323 (M50) based on the proper motions and photometry of its constituent stars
 | last1=Frolov | first1=V. N. | last2=Ananjevskaja | first2=Yu. K.
 | last3=Polyakov | first3=E. V. | display-authors=1
 | journal=Astronomy Letters | postscript=.
 | volume=38 | issue=2 | pages=74–86 | date=February 2012
 | doi=10.1134/S106377371202003X | bibcode=2012AstL...38...74F | s2cid=255199532 }}</ref>

}}
{{noteslist}}

==External links==
{{Commons category|Messier 50}}
* [https://www.youtube.com/watch?v=17LITLns-pk Messier 50 - at Deep Sky Videos]
* [http://messier.seds.org/m/m050.html Messier 50, SEDS Messier pages]
* [https://www.waid-observatory.com/m050-2006-04-07.html M50 Image by Waid Observatory]
* {{WikiSky}}
{{Sky|07|03.2|00|-|08|20|00|3200}}
*{{APOD |date=28 January 1997|title=Open Cluster M50}}

{{Messier objects}}
{{Ngc25}}
{{Monoceros}}
{{Portal bar|Astronomy|Stars|Outer space}}

[[Category:Open clusters|Messier 050]]
[[Category:Orion–Cygnus Arm]]
[[Category:Monoceros|Messier 050]]
[[Category:Messier objects|050]]
[[Category:NGC objects|Messier 050]]
[[Category:Astronomical objects discovered in 1711|?]]