View source for Messier 30

{{short description|Globular cluster in the constellation Capricornus}}
{{Use dmy dates|date=February 2021}}
{{Infobox globular cluster
| name = [[Messier object|Messier]] 30
| image = [[File:M30 NASA.jpg|300px|]]
| caption = Open cluster Messier 30 in Capricornus
| epoch = [[J2000]]
| class = V<ref name=hcob849_11/>
| ra = {{RA|21|40|22.12}}<ref name=aj140_6_1830/>
| dec = {{DEC|–23|10|47.5}}<ref name=aj140_6_1830/>
| dist_ly = {{cvt|27.14|+/-|0.65|kly|kpc|lk=on|sigfig=2}}<ref name=apj657_1_286/><ref name=aa555_36/>
| appmag_v = 7.2<ref>{{cite web |url=http://www.messier.seds.org/m/m030.html |title=Messier 30 |access-date=22 July 2024 |website=SEDS Messier Catalog}}</ref>
| size_v = 12'.0
| constellation = [[Capricornus constellation|Capricornus]]
| mass_msol = {{Val|1.6|e=5}}<ref name=mnras392_1_113/>
| radius_ly =
| v_hb =
| age = 12.93&nbsp;[[Gigayear|Gyr]]<ref name=mnras404_3_1203/>
| metal_fe = –2.27<ref name=apj742_1_51/>
| notes =
| names = M30, [[New General Catalogue|NGC]] 7099, GCl 122<ref name="simbad"/>
}}

'''Messier 30''' (also known as '''M30''', '''NGC 7099''', or the '''Jellyfish Cluster''') is a [[globular cluster]] of stars in the southeast of the southern [[constellation]] of [[Capricornus]], at about the declination of the Sun when the latter is at [[December solstice]].{{efn|Thus, its northern limit for good visibility is a few degrees south of the [[Arctic Circle]], all year}} It was discovered by the French astronomer [[Charles Messier]] in 1764, who described it as a circular [[nebula]] without a star. In the [[New General Catalogue]], compiled during the 1880s, it was described as a "remarkable globular, bright, large, slightly oval." It can be easily viewed with a pair of 10×50 binoculars,<ref name=jbaa118_4_231/> forming a patch of hazy light some 4&nbsp;[[arcminute]]s wide that is slightly elongated along the east–west axis.<ref name=jbaa118_4_231/> With a larger instrument, individual stars can be resolved and the cluster will cover an angle of up to 12&nbsp;[[arcminute]]s across graduating into a compressed core about one arcminute wide that has further star density within.<ref name=omeara1998/> 

It is longest observable (opposed to the Sun) in the first half of August.{{efn|This is when it is risen, throughout the night, so culminates about midnight. The Earth's orbit means the sun leaves Capricornus, as if it heads east a few degrees NNE, on about 15 or 16 February, having figured in the constellation for a month.}}<ref name=jbaa118_4_231/>

M30 is centered 27,100 [[light-year]]s away from [[Earth]] with a roughly 2.5% margin of error,<ref name=aa555_36/> and is about 93 light-years across.<ref name=omeara1998/> The estimated age is roughly 12.9 billion years<ref name=mnras404_3_1203/> and it forms a mass of about 160,000 times the [[solar mass|mass of the Sun]] ({{solar mass}}).<ref name=mnras392_1_113/> The cluster is following a [[retrograde orbit]] (against the general flow) through the inner galactic halo, suggesting that it was acquired from a [[satellite galaxy]] rather than forming within the [[Milky Way]].<ref name=mnras404_3_1203/> It is in this epoch {{cvt|22.2|kly|kpc}}, from the center of the galaxy, compared to an estimated {{cvt|26|kly|kpc}} for the [[Sun]].<ref name=aj117_1_277/>

The cluster has passed through a dynamic process called [[Core collapse (cluster)|core collapse]] and now has a concentration of mass at its core of about a million times the [[solar mass|Sun's mass]] per cubic [[parsec]]. This makes it one of the highest density regions in the [[Milky Way]] galaxy. Stars in such close proximity will experience a high rate of interactions that can create [[binary star]] systems, as well as a type of star called a [[blue straggler]] that is formed by mass transfer.<ref name=apj657_1_286/> A process of mass segregation may have caused the central region to gain a greater proportion of higher mass stars, creating a color gradient with increasing blueness toward the middle of the cluster.<ref name=aj119_3_1259/>
[[File:M30map.png|thumbnail|Masp showing the location of M30]]


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

==References and footnotes==
{{reflist|refs=
<ref name=aj140_6_1830>{{citation | display-authors=1 | last1=Goldsbury | first1=Ryan | last2=Richer | first2=Harvey B. | last3=Anderson | first3=Jay | last4=Dotter | first4=Aaron | last5=Sarajedini | first5=Ata | last6=Woodley | first6=Kristin | title=The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters | journal=The Astronomical Journal | volume=140 | issue=6 | pages=1830–1837 |date=December 2010 | doi=10.1088/0004-6256/140/6/1830 | bibcode=2010AJ....140.1830G | postscript=. |arxiv = 1008.2755 | s2cid=119183070 }}</ref>

<ref name=apj657_1_286>{{citation | display-authors=1 | last1=Lugger | first1=Phyllis M. | last2=Cohn | first2=Haldan N. | last3=Heinke | first3=Craig O. | last4=Grindlay | first4=Jonathan E. | last5=Edmonds | first5=Peter D. | title=Chandra X-Ray Sources in the Collapsed-Core Globular Cluster M30 (NGC 7099) | journal=The Astrophysical Journal | volume=657 | issue=1 | pages=286–301 |date=March 2007 | doi=10.1086/507572 | bibcode=2007ApJ...657..286L |arxiv = astro-ph/0606382 | s2cid=14188771 }}</ref>

<ref name=aa555_36>{{citation | display-authors=1 | last1=Kains | first1=N. | last2=Bramich | first2=D. | last3=Arellano Ferro | first3=A. | last4=Figuera Jaimes | first4=R. | last5=Jorgensen | first5=U.G. | last6=Giridhar | first6=S. | last7=Penny | first7=M.T. | last8=Alsubai | first8=K. | last9=Andersen | first9=J.M. | title=Estimating the parameters of globular cluster M 30 (NGC 7099) from time-series photometry | journal=Astronomy and Astrophysics | volume=555 | issue=1 | pages=36–50 |year=2016 | doi=10.1051/0004-6361/201321819 | bibcode=2013A&A...555A..36K |arxiv = 1305.3606 | s2cid=53669510 }}</ref>

<ref name=aj119_3_1259>{{citation | last1=Howell | first1=Justin H. | last2=Guhathakurta | first2=Puragra | last3=Tan | first3=Amy | title=Radial Color Gradient and Main-Sequence Mass Segregation in M30 (NGC 7099) | journal=The Astronomical Journal | volume=119 | issue=3 | pages=1259–1267 |date=March 2000 | doi=10.1086/301270 | bibcode=2000AJ....119.1259H |arxiv = astro-ph/9912002 | s2cid=15083719 }}</ref>

<ref name=omeara1998>{{citation | first1=Stephen James | last1=O'Meara | title=The Messier objects | series=Deep-sky companions | publisher=[[Cambridge University Press]] | year=1998 | isbn=978-0-521-55332-2 | url=https://books.google.com/books?id=jis4evHuuzUC&pg=PA108 | page=108 }}</ref>

<ref name=mnras404_3_1203>{{citation | last1=Forbes | first1=Duncan A. | last2=Bridges | first2=Terry | title=Accreted versus in situ Milky Way globular clusters | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=404 | issue=3 | pages=1203–1214 |date=May 2010 | doi=10.1111/j.1365-2966.2010.16373.x | doi-access=free | bibcode=2010MNRAS.404.1203F |arxiv = 1001.4289 | s2cid=51825384 }}</ref>

<ref name=aj117_1_277>{{citation | display-authors=1 | last1=Dinescu | first1=Dana I. | last2=van Altena | first2=William F. | last3=Girard | first3=Terrence M. | last4=López | first4=Carlos E. | title=Space Velocities of Southern Globular Clusters. II. New Results for 10 Clusters | journal=The Astronomical Journal | volume=117 | issue=1 | pages=277–285 |date=January 1999 | doi=10.1086/300699 | bibcode=1999AJ....117..277D | doi-access=free }}</ref>

<ref name=jbaa118_4_231>{{citation | last1=Bone | first1=N. M. | title=Sky notes, 2008 August & September | journal=Journal of the British Astronomical Association | volume=118 | issue=4 | pages=231–232 |date=August 2008 | bibcode=2008JBAA..118..231B }}</ref>

<ref name="simbad">{{cite simbad | title=M 30 | access-date=2006-11-16}}</ref>

<ref name=mnras392_1_113>{{citation | last1=Vande Putte | first1=D. | last2=Cropper | first2=Mark | title=Detecting the effect of globular cluster impacts on the disc of the Milky Way | journal=Monthly Notices of the Royal Astronomical Society | volume=392 | issue=1 | pages=113–124 |date=January 2009 | doi=10.1111/j.1365-2966.2008.14072.x | doi-access=free | bibcode=2009MNRAS.392..113V | arxiv=0811.3106 | s2cid=17244698 }}</ref>

<ref name=hcob849_11>{{citation | last1=Shapley | first1=Harlow | last2=Sawyer | first2=Helen B. | title=A Classification of Globular Clusters | journal=Harvard College Observatory Bulletin | issue=849 | pages=11–14 |date=August 1927 | bibcode=1927BHarO.849...11S | postscript=. | volume=849 }}</ref>

<ref name=apj742_1_51>{{citation | display-authors=1 | last1=Boyles | first1=J. | last2=Lorimer | first2=D. R. | last3=Turk | first3=P. J. | last4=Mnatsakanov | first4=R. | last5=Lynch | first5=R. S. | last6=Ransom | first6=S. M. | last7=Freire | first7=P. C. | last8=Belczynski | first8=K. | title=Young Radio Pulsars in Galactic Globular Clusters | journal=The Astrophysical Journal | volume=742 | issue=1 | page=51 |date=November 2011 | doi=10.1088/0004-637X/742/1/51 | bibcode=2011ApJ...742...51B | postscript=. |arxiv = 1108.4402 | s2cid=118649860 }}</ref>

}}

==Notes==
{{notelist}}

==External links==
{{Commons category|Messier 30}}
* [http://www.messier.seds.org/m/m030.html Globular Cluster M30 @ SEDS Messier pages]
* [http://gclusters.altervista.org/cluster_4.php?ggc=M+30 Messier 30, Galactic Globular Clusters Database page]
* {{cite web|last=Gray|first=Meghan|title=M30 – Globular Cluster|url=http://www.deepskyvideos.com/videos/messier/M30_globular_cluster.html|work=Deep Sky Videos|publisher=[[Brady Haran]]}}
* {{WikiSky}}

{{Sky|21|40|22.03|-|23|10|44.6|26000}}
{{Messier objects}}
{{Ngc75}}
{{Capricornus}}
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{{DEFAULTSORT:Messier 30}}
[[Category:Globular clusters|Messier 030]]
[[Category:Capricornus|Messier 030]]
[[Category:Messier objects|030]]
[[Category:NGC objects|Messier 030]]
[[Category:Astronomical objects discovered in 1764|17640803]]
[[Category:August]]
[[Category:Discoveries by Charles Messier]]