View source for Beehive Cluster

{{Short description|Open cluster in the constellation Cancer}}
{{about|the Beehive Cluster||Beehive}}
{{Infobox open cluster
| name = Messier 44 / Beehive Cluster
| image = M44-Star-Cluster.png
| caption = The Beehive Cluster in Cancer constellation (north is to the right)
| epoch = J2000.0
| constellation = [[Cancer (constellation)|Cancer]]
| ra = 08<sup>h</sup>&nbsp;40.4<sup>m</sup>
| dec = 19° 59′
| dist_ly = 610 ly<ref>{{Cite web|title=NGC 2632|url=http://simbad.u-strasbg.fr/simbad/sim-id?mescat.distance=on&Ident=%401110595&Name=NGC++2632&submit=display+selected+measurements#lab_meas|access-date=2020-06-11|website=sim-id}}</ref>
| dist_pc = 187 pc 
| appmag_v = 3.7<ref name="SEDS">
{{cite web
 |title=Messier 44
 |url=http://messier.seds.org/m/m044.html
 |work=[[SEDS]]
 |access-date=2009-12-10
}}</ref>
| size_v = 95′
| mass_kg = 
| mass_msol = ~500–600
| radius_ly = 11.42 ly
| v_hb = 
| age = ~600–700 million years
| names = Praesepe, M44, NGC 2632, [[Collinder catalogue|Cr]] 189
}}
[[File:Presepemap.png|thumb|Map showing the location of M44 in the constellation of Cancer]]
The '''Beehive Cluster''' (also known as '''Praesepe''' (Latin for "manger", "cot" or "crib"), '''M44''', '''NGC 2632''', or '''Cr 189'''), is an [[open cluster]] in the constellation [[Cancer (constellation)|Cancer]]. One of the nearest open clusters to [[Earth]], it contains a larger population of stars than other nearby bright open clusters holding around 1,000 [[Star|stars]]. Under dark skies, the Beehive Cluster looks like a small [[Nebula|nebulous]] object to the naked eye, and has been known since ancient times. Classical astronomer [[Ptolemy]] described it as a "nebulous mass in the breast of Cancer". It was among the first objects that [[Galileo]] studied with his
telescope.<ref name="Messier44">{{cite web |title=Messier 44: Observations and Descriptions |url=http://www.maa.clell.de/Messier/Mdes/dm044.html |access-date=2008-08-13 |archive-date=2016-04-13 |archive-url=https://web.archive.org/web/20160413184911/http://www.maa.clell.de/Messier/Mdes/dm044.html |url-status=dead }}</ref>

Its age and proper motion coincide with those of the [[Hyades (star cluster)|Hyades]], suggesting they may share similar origins.<ref name="Klein-Wassink1927">
{{cite journal
|last=Klein-Wassink |first=W.J.
|date=1927
|title=The proper motion and the distance of the Praesepe cluster
|journal=Publications of the Kapteyn Astronomical Laboratory Groningen
|volume=41
|pages=1–48
|bibcode=1927PGro...41....1K
}}</ref><ref name="Dobbie2006">
{{cite journal
|author=Dobbie PD |author2=Napiwotzki R |author3=Burleigh MR |date=2006
|title=New Praesepe white dwarfs and the initial mass-final mass relation
|journal=[[Monthly Notices of the Royal Astronomical Society]]
|volume=369
|issue=1 |pages=383–389
|bibcode=2006MNRAS.369..383D
|doi=10.1111/j.1365-2966.2006.10311.x
|doi-access=free |arxiv=astro-ph/0603314 |s2cid=17914736 |display-authors=etal}}</ref> Both clusters also contain [[red giants]] and [[white dwarfs]], which represent later stages of stellar evolution, along with many [[main sequence]] stars.

The distance to M44 is often cited to be between 160 and 187 [[parsecs]] (520–610 [[light years]]),<ref name="Pinfield2003">
{{cite journal
 |author=Pinfield DJ
 |display-authors=4
 |author2=Dobbie PD
 |author3=Jameson F
 |author4=Steele IA
 |author5=Jones HRA
 |author6=Katsiyannis AC
 |date=2003
 |title=Brown dwarfs and low-mass stars in the Pleiades and Praesepe: Membership and binarity
 |journal=[[Monthly Notices of the Royal Astronomical Society]]
 |volume=342 |issue=4
 |pages=1241–1259
 |bibcode= 2003MNRAS.342.1241P
 |doi=10.1046/j.1365-8711.2003.06630.x
|doi-access=free
 |arxiv = astro-ph/0303600 |s2cid=285922
 }}</ref><ref name="Kraus2007">
{{cite journal
 |author=Kraus AL |author2=Hillenbrand LA
 |date=2007
 |title=The stellar populations of Praesepe and Coma Berenices
 |journal=[[Astronomical Journal]]
 |volume=134 |issue=6
 |pages=2340–2352
 |bibcode=2007AJ....134.2340K
 |doi=10.1086/522831
|arxiv = 0708.2719 |s2cid=15945900
 }}</ref><ref name="WEBDA">[http://www.univie.ac.at/webda/ WEBDA]</ref> but the revised [[Hipparcos]] parallaxes (2009) for Praesepe members and the latest infrared [[color-magnitude diagram]] favors an analogous distance of 182 pc.<ref name=vanleeuwen09>van Leeuwen, F. [http://adsabs.harvard.edu/abs/2009A%26A...497..209V "Parallaxes and proper motions for 20 open clusters as based on the new Hipparcos catalogue"], ''A&A'', 2009</ref><ref name=majaess11>Majaess, D.; Turner, D.; Lane, D.; Krajci, T. [http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1102.1705 "Deep Infrared ZAMS Fits to Benchmark Open Clusters Hosting delta Scuti Stars"], ''Journal of the American Association of Variable Star Observers'', 2011</ref> There are better age estimates of around 600 million years<ref name="Dobbie2006"/><ref name="Kraus2007"/><ref name="Adams2002">
{{cite journal
|author=Adams JD |author2=Stauffer JR |author3=Skrutskie MF |date=2002
|title=Structure of the Praesepe Star Cluster
|journal=[[Astronomical Journal]]
|volume=124 |issue=3 |pages=1570–1584
|bibcode=2002AJ....124.1570A
|doi=10.1086/342016
|display-authors=etal|doi-access=free}}</ref> (compared to about 625 million years for the Hyades).<ref name="Perryman1998">
{{cite journal
|author=Perryman M
|author2=Brown A
|author3=Lebreton Y
|author4=Gomez A
|author5=Turon C
|author6=Cayrel de Strobel G
|author7=Mermilliod J
|author8=Robichon N
|author9=Kovalevsky J
|author10=Crifo F
|display-authors=6
|date=1998
|title=The Hyades: Distance, structure, dynamics, and age
|journal=[[Astronomy & Astrophysics]]
|volume=331 |pages=81–120
|bibcode=1998A&A...331...81P
|arxiv = astro-ph/9707253 }}</ref> The diameter of the bright inner cluster core is about 7.0 parsecs (23 light years).<ref name="Adams2002"/>

At 1.5° across, the cluster easily fits within the field of view of binoculars or low-powered small telescopes. [[Regulus]], [[Castor (star)|Castor]], and [[Pollux (star)|Pollux]] are [[guide star]]s. 

== History ==
In 1609, [[Galileo]] first telescopically observed the Beehive and was able to resolve it into 40 stars.  [[Charles Messier]] added it to [[Messier object|his famous catalog]] in 1769 after precisely measuring its position in the sky. Along with the [[Orion Nebula]] and the [[Pleiades]] cluster, Messier's inclusion of the Beehive has been noted as curious, as most of Messier's objects were much fainter and more easily confused with comets. Another possibility is that Messier simply wanted to have a larger catalog than his scientific rival [[Nicolas Louis de Lacaille|Lacaille]], whose 1755 catalog contained 42 objects, and so he added some well-known bright objects to boost his list.<ref>
{{cite web
 |author=Frommert, Hartmut
 |date=1998
 |url=http://messier.seds.org/m-q&a.html#why_M42-45
 |title=Messier Questions & Answers
 |publisher=[[SEDS]]
 |access-date=2005-03-01
 |archive-url=https://web.archive.org/web/20050209083425/http://www.seds.org/messier/m-q%26a.html#why_M42-45
 |archive-date=9 February 2005
 |url-status=live
 }}</ref> [[Wilhelm Schur]], as director of the [[Göttingen Observatory]], drew a map of the cluster in 1894.[[File:Wilhelm Schur, 004.jpg|left|thumb|[[Wilhelm Schur|Wilhelm Schur's]] map of the Beehive Cluster in 1894]]Ancient Greeks and Romans saw this object as a manger from which two donkeys, the adjacent stars [[Gamma Cancri|Asellus Borealis]] and [[Delta Cancri|Asellus Australis]], are eating; these are the donkeys that [[Dionysos]] and [[Silenus]] rode into battle against the [[Titan (mythology)|Titans]].<ref>
{{cite web |title=M44 |url=http://messier.seds.org/m/m044.html |publisher=[[SEDS]]|access-date=2005-02-06}}</ref>

[[Hipparchus]] (''c''.130 BC) refers to the cluster as ''Nephelion'' ("Little Cloud") in his star catalog.<ref name="Allen1899"/> [[Claudius Ptolemy]]'s ''[[Almagest]]'' includes the Beehive Cluster as one of seven "nebulae" (four of which are real<ref>{{Cite web | url=http://messier.seds.org/xtra/history/deepskyd.html#ptolemy | title=The Discovery of the Deep Sky Objects}}</ref>), describing it as "The Nebulous Mass in the Breast (of Cancer)".<ref>{{cite web|url=http://messier.seds.org/m/m044.html|title=Messier Object 44|publisher=[[SEDS]]|access-date=2013-09-28}}</ref> [[Aratus]] (''c''.260–270 BC) calls the cluster ''Achlus'' or "Little Mist" in his poem ''Phainomena''.<ref name="Allen1899"/>

[[Johann Bayer]] showed the cluster as a nebulous star on his [[Uranometria]] atlas of 1603, and labeled it Epsilon. The letter is now applied specifically to the brightest star of the cluster [[Epsilon Cancri]], of magnitude 6.29.<ref name=Ridpath>{{cite web |url = http://www.ianridpath.com/startales/cancer.html#praesepe |title = Cancer – the asses and the Manger |website = Star Tales (online edition) |access-date = 2023-11-19}}</ref> Bayer also cited the name ''Melleff'' or ''Meeleph'' for the cluster, from Arabic ''Al Ma'laf'', the Stall;<ref name="Allen1899"/> as ''Meleph'', this name is also now applied specifically to the star Epsilon Cancri.<ref name="IAU-CSN-new"/>

This perceived nebulous object is in the [[Ghost (Chinese constellation)|Ghost]] (Gui Xiu), the 23rd [[Twenty-Eight Mansions|lunar mansion]] of ancient Chinese astrology.  Ancient Chinese skywatchers saw this as a ghost or demon riding in a carriage and likened its appearance to a "cloud of pollen blown from willow catkins". It was also known by the somewhat less romantic name of ''Jishi qi'' (積屍氣, also transliterated ''Tseih She Ke''), the "Exhalation of Piled-up Corpses".<ref name="Allen1899"/> It is also known simply as Jishi (積屍), "cumulative corpses".

== Morphology and composition ==
Like many [[star cluster]]s of all kinds, Praesepe has experienced [[mass segregation]].<ref name="Kraus2007"/><ref name="Adams2002"/><ref name="Portegies2001">
{{cite journal
 |author=Portegies Zwart SF
 |author2=McMillan SL
 |author3=Hut P
 |author4=Makino J
 |date=2001
 |title=Star cluster ecology IV. Dissection of an open star cluster: Photometry
 |journal=[[Monthly Notices of the Royal Astronomical Society]]
 |volume=321 |issue=2
 |pages=199–226
 |bibcode= 2001MNRAS.321..199P
 |doi=10.1046/j.1365-8711.2001.03976.x
|doi-access=free
 |arxiv = astro-ph/0005248 |s2cid=18396503
 }}</ref> This means that bright massive stars are concentrated in the cluster's core, while dimmer and less massive stars populate its halo (sometimes called the ''corona''). The cluster's core radius is estimated at 3.5 parsecs (11.4 light years); its half-mass radius is about 3.9 parsecs (12.7 light years); and its  [[Roche limit|tidal radius]] is about 12 parsecs (39 light years).<ref name="Kraus2007"/><ref name="Adams2002"/> However, the tidal radius also includes many stars that are merely "passing through" and not ''bona fide'' cluster members.
[[File:M44 47x300s-10°C O30 G0 PM RGB 03032022.jpg|thumb|The Beehive Cluster in Cancer]]

Altogether, the cluster contains at least 1000 gravitationally bound stars, for a total mass of about 500–600 Solar masses.<ref name="Kraus2007" /><ref name="Adams2002" /> A recent survey counts 1010 high-probability members, of which 68% are [[red dwarf|M dwarfs]], 30% are Sun-like stars of [[stellar classification|spectral classes]] F, G, and K, and about 2% are bright stars of spectral class A.<ref name="Kraus2007" /> Also present are five giant stars, four of which have spectral class K0 III and the fifth G0 III.<ref name="Klein-Wassink1927" /><ref name="Kraus2007" /><ref name="Abt1999">
{{cite journal
 |author=Abt HA |author2=Willmarth DW
 |date=1999
 |title=Binaries in the Praesepe and Coma star clusters and their implications for binary evolution
 |journal=[[Astrophysical Journal]]
 |volume=521 |issue=2
 |pages=682–690
 |bibcode=1999ApJ...521..682A
 |doi=10.1086/307569
|s2cid=119772785
 |doi-access=free
 }}</ref>

So far, eleven [[white dwarf]]s have been identified, representing the final evolutionary phase of the cluster's most massive stars, which originally belonged to spectral type B.<ref name="Dobbie2006"/> [[Brown dwarf]]s, however, are rare in this cluster,<ref name="Gonzalez-Garcia2006"/> probably because they have been lost by tidal stripping from the halo.<ref name="Kraus2007"/> A brown dwarf has been found in the [[eclipsing binary]] system AD 3116.<ref name="Gillen2018"/>

The cluster has a visual brightness of magnitude 3.7. Its brightest stars are blue-white and of magnitude 6 to 6.5. [[42 Cancri]] is a confirmed member.

== Planets ==
In September 2012, two planets which orbit separate stars were discovered in the Beehive Cluster. The finding was significant for being the first planets detected orbiting stars like [[Earth]]'s [[Sun]] that were situated in stellar clusters. Planets had previously been detected in such clusters, but not orbiting stars like the Sun.<ref name="Quinn2012"/>

The planets have been designated [[Pr0201 b]] and [[Pr0211 b]]. The 'b' at the end of their names indicates that the bodies are planets. The discoveries are what have been termed [[hot Jupiter]]s, massive [[gas giants]] that, unlike the planet [[Jupiter]], orbit very close to their parent stars.<ref name="Quinn2012"/>

The announcement describing the planetary finds, written by Sam Quinn as the lead author, was published in the [[The Astrophysical Journal|''Astrophysical Journal'']] Letters. Quinn's team worked with David Latham of the [[Harvard–Smithsonian Center for Astrophysics]], utilizing the [[Smithsonian Astrophysical Observatory]]'s [[Fred Lawrence Whipple Observatory]].<ref name="Quinn2012"/><ref>{{Cite web|url=http://www.jpl.nasa.gov/news/news.php?release=2012-289|title=First Planets Found Around Sun-Like Stars in a Cluster|website=[[Jet Propulsion Laboratory]] |access-date=September 14, 2012}}</ref>

In 2016 additional observations found a second planet in the [[Pr0211]] system, Pr0211 c. This made Pr0211 the first multi-planet system to be discovered in an open cluster.<ref name="Malavolta2016"/>

The [[Kepler space telescope]], in its [[Kepler space telescope#Second Light (K2)|K2 mission]], discovered planets around several more stars in the Beehive Cluster. The stars K2-95,<ref name="Obermeier2016"/> K2-100, K2-101, K2-102, K2-103, and K2-104<ref name="Mann2017"/> host a single planet each, and K2-264 has a two-planet system.<ref name="Rizzuto2018"/>

==Gallery==
<gallery>
File:Comet-Neat-Messier-44.jpeg|Photo of comet C/2001 Q4 (NEAT) next to Messier 44
File:M44 Heggie.jpg|Widefield image of the Beehive Cluster
</gallery>

==See also==
* [[List of Messier objects]]
*[[Cancer (Chinese astronomy)]]
*[[List of open clusters]]
*[[Messier object]]
*[[New General Catalogue]]
*[[Open cluster family]]
*[[Open cluster remnant]]

== References ==
{{Reflist|30em|refs=

<ref name="Allen1899">{{cite book |last=Allen |first=Richard Hinckley |date=1899 |title=Star Names: Their Lore and Meaning |url=https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Cancer*.html |pages=112-113}}</ref>

<ref name="IAU-CSN-new">{{cite web |title=IAU Catalog of Star Names |url=https://exopla.net/star-names/modern-iau-star-names/ |access-date=24 April 2025}}</ref>

<ref name="Gonzalez-Garcia2006">
{{cite journal
 |author=Gonzalez-Garcia BM
 |display-authors=4
 |author2=Zapatero Osorio MR
 |author3=Bejar VJS
 |author4=Bihain G
 |author5=Barrado y Navascues D
 |author6=Caballero JA
 |author7=Morales-Calderon M
 |date=2006
 |title=A search for substellar members in the Praesepe and Sigma Orionis clusters
 |journal=[[Astronomy & Astrophysics]]
 |volume=460 |issue=3
 |pages=799–810
|arxiv = astro-ph/0609283 |bibcode = 2006A&A...460..799G |doi = 10.1051/0004-6361:20065909 |s2cid=119376131
 }}</ref>

<ref name="Quinn2012">{{cite journal |last1=Quinn |first1=Samuel N. |last2=White |first2=Russel J. |display-authors=etal |date=September 2012 |title=Two "b"s in the Beehive: The Discovery of the First Hot Jupiters in an Open Cluster |journal=[[The Astrophysical Journal Letters]] |volume=756 |issue=2 |pages=L33 |doi=10.1088/2041-8205/756/2/L33 |arxiv=1207.0818 |bibcode=2012ApJ...756L..33Q|s2cid=118825401 }}</ref>

<ref name="Malavolta2016">{{cite journal |last1=Malavolta |first1=L. |last2=Nascimbeni |first2=V. |display-authors=etal |date=April 2016 |title=The GAPS programme with HARPS-N at TNG. XI. Pr 0211 in M 44: the first multi-planet system in an open cluster |journal=[[Astronomy & Astrophysics]] |volume=588 |issue= |pages=A118 |doi=10.1051/0004-6361/201527933 |arxiv=1602.00009 |bibcode=2016A&A...588A.118M |s2cid=119207951}}</ref>

<ref name="Obermeier2016">{{cite journal |last1=Obermeier |first1=Christian |last2=Henning |first2=Thomas |display-authors=etal |date=December 2016 |title=K2 Discovers a Busy Bee: An Unusual Transiting Neptune Found in the Beehive Cluster |journal=[[The Astronomical Journal]] |volume=152 |issue=6 |pages=223 |doi=10.3847/1538-3881/152/6/223 |arxiv=1608.04760 |bibcode=2016AJ....152..223O |doi-access=free }}</ref>

<ref name="Mann2017">{{cite journal |last1=Mann |first1=Andrew W. |last2=Gaidos |first2=Eric |display-authors=etal |date=February 2017 |title=Zodiacal Exoplanets in Time (ZEIT). IV. Seven Transiting Planets in the Praesepe Cluster |journal=[[The Astronomical Journal]] |volume=153 |issue=2 |pages=64 |doi=10.1088/1361-6528/aa5276 |arxiv=1609.00726 |bibcode=2017AJ....153...64M|s2cid=119260879 }}</ref>

<ref name="Gillen2018">{{cite journal |last1=Gillen |first1=Edward |last2=Hillenbrand |first2=Lynne A. |display-authors=etal |date=November 2017 |title=New Low-mass Eclipsing Binary Systems in Praesepe Discovered by K2 |journal=[[The Astrophysical Journal]] |volume=849 |issue=1 |pages=11 |doi=10.3847/1538-4357/aa84b3 |arxiv=1706.03084 |bibcode=2017ApJ...849...11G |doi-access=free }}</ref>

<ref name="Rizzuto2018">{{cite journal |last1=Rizzuto |first1=Aaron C. |last2=Vanderburg |first2=Andrew |display-authors=etal |date=November 2018 |title=Zodiacal Exoplanets in Time (ZEIT). VIII. A Two-planet System in Praesepe from K2 Campaign 16 |journal=[[The Astronomical Journal]] |volume=156 |issue=5 |pages=195 |doi=10.3847/1538-3881/aadf37 |arxiv=1808.07068 |bibcode=2018AJ....156..195R |doi-access=free }}</ref>

}}

== External links ==
{{Commons category|Beehive Cluster}}
* [https://www.darkatmospheres.com/astro/gallery/clusters/enlarge.php?fileBase=clusters_5 M44 Photo detail Dark Atmospheres]
* [http://messier.seds.org/m/m044.html Messier 44, SEDS Messier pages]
* [http://www.nightskyinfo.com/archive/m44_open_cluster NightSkyInfo.com – M44, the Beehive Cluster] {{Webarchive|url=https://web.archive.org/web/20090225012455/http://www.nightskyinfo.com/archive/m44_open_cluster |date=2009-02-25 }}
* {{APOD |date=3 August 1998 |title=M44: A Beehive of Stars}}{{WikiSky|NGC 2632|name=The Beehive Cluster}}
* [http://www.constellation-guide.com/praesepe-m44-the-beehive-cluster/ Praesepe (M44) at Constellation Guide]

{{Sky|08|40.4|00|+|19|41|00|577}}

{{Messier objects}}
{{Ngc30}}
{{Stars of Cancer}}
{{Portal bar|Astronomy|Stars|Outer space}}
{{DEFAULTSORT:Beehive Cluster}}
[[Category:Cancer (constellation)]]
[[Category:Orion–Cygnus Arm]]
[[Category:Open clusters]]
[[Category:Messier objects|Beehive Cluster]]
[[Category:NGC objects]]
[[Category:Astronomical objects known since antiquity]]
[[Category:Dionysus]]
[[Category:Silenus]]