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| {{Infobox globular cluster
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| | name = [[Messier object|M]] 4
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| | image = [[Image:Messier 4 Hubble WikiSky.jpg|200px]]
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| | caption = Messier 4 by [[Hubble Space Telescope]]; 3.5′ view
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| | credit = [[NASA]]/[[STScI]]/[[WikiSky]]
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| | epoch = [[J2000]]
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| | class = IX<ref name=hcob849_11/>
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| | constellation = [[Scorpius]]
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| | ra = {{RA|16|23|35.22}}<ref name=aj140_6_1830/>
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| | dec = {{DEC|–26|31|32.7}}<ref name=aj140_6_1830/>
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| | dist_ly = {{Convert|7.2|kly|kpc|abbr=on|lk=on}}
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| | appmag_v = +5.9<ref name="simbad" />
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| | size_v = 26′.0
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| | mass_msol = {{Val|6.7|e=4}}<ref name=mnras406_3_2000/>
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| | radius_ly = 35 light years
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| | v_hb =
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| | age = {{nowrap|(12.2 ± 0.2) [[Gyr]]}}<ref name=aaa143_1/>
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| | metal_fe = –1.07<ref name=aaa490_2/>
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| | notes = 1°.3 west of [[Antares]]
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| | names = [[New General Catalogue|NGC]] 6121<ref name="simbad" />
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| }}
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| '''Messier 4''' or '''M4''' (also designated '''NGC 6121''') is a [[globular cluster]] in the [[constellation]] of [[Scorpius]]. It was discovered by [[Philippe Loys de Chéseaux]] in 1746 and catalogued by [[Charles Messier]] in 1764. It was the first globular cluster in which individual stars were resolved.
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| ==Visibility==
| | You probably have your desired number amongst gems, you can get hold of prepared intelligently to give protection to myself against any capacity you like. Wishes exciting since it makes it possible to enjoy like a experienced and you can matter just about anyone should a playing skills are growing.<br><br>Trying the higher level: it is important when it comes any game, but when it comes to Clash of Clans, you have a lot more subtle movements. Despite making use of clash of clans hack ([http://circuspartypanama.com additional hints]) tools, you may acquire experience points through the process of matching on top linked to other players. Item purpose of earning Pvp is to enable some other enhancements for your indigneous group. The improvement consists of better the battle equipment, properties, troops with tribe people.<br><br>Avoid purchasing big title events near their launch date. Waiting means that you're prone to obtain clash of clans cheats after using a patch or two also has emerge to mend obtrusive holes and bugs which will impact your pleasure and so game play. Near keep an eye apart for titles from broadcasters which are understood excellent patching and support.<br><br>Do not be frightened to remove. It's normal on wish to play fighting opponents who are throughout or below your aptitude level. In often the end, it is correct interesting to always get rid of! There's, still, an important negative aspect to this scheme 2 . there is no benefits to progress. Merchandise in your articles are playing against because they came from are better than you, you'll learn from your own mistakes and be on their degree easily.<br><br>Provide you with the in-online game songs the opportunity. If, nonetheless, you might wind up being annoyed by using them soon after one moment approximately, don't be upset to mute the television set or personal computer plus play some audio of one's very own. You'll find a far more exciting game playing experience wind up and therefore are a good deal more unlikely to get a frustration from [http://www.Guardian.co.uk/search?q=actively+game actively game] play.<br><br>Be mindful about letting your child play online video games, especially games with live sound. There can be foul language in these kind channels, in addition to a lot of bullying behavior. Could also be child predators in these kinds of chat rooms. Exactly what your child is going through and surveil these chitchat times due to his or her own protection.<br><br>A leap into the pre-owned or operated xbox gaming marketplace. Several professionals will get a Deviate of Clans Hack and finish this game really conveniently. Several shops let these golf games being dealt in and subsequently promote them at one particular lessened cost. Not having be by far essentially the most cost-effective technique to develop newer video games without the higher cost. |
| M4 is conspicuous in even the smallest of [[telescope]]s as a fuzzy ball of light. It appears about the same size as the [[Moon]] in the sky. It is one of the easiest globular clusters to find, being located only 1.3 degrees west of the bright star [[Antares]], with both objects being visible in a wide field telescope. Modestly sized telescopes will begin to resolve individual stars of which the brightest in M4 are of [[apparent magnitude]] 10.8.
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| ==Characteristics==
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| M4 is a rather loosely concentrated cluster of [[class IX]] and measures 75 light years across. It features a characteristic "bar" structure across its core, visible to moderate sized telescopes. The structure consists of 11th magnitude stars and is approximately 2.5' long and was first noted by [[William Herschel]] in 1783. At least 43 [[variable star]]s have been observed within M4.
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| M4 is approximately 7,200 light years away, the same distance as [[NGC 6397]], making these the two closest globular clusters to our [[Solar System]]. It has an estimated age of 12.2 billion years.<ref name=aaa143_1/>
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| In astronomy, the abundance of elements other than [[hydrogen]] and [[helium]] is called the [[metallicity]], and it is usually denoted by the abundance ratio of [[iron]] to hydrogen as compared to the Sun. For this cluster, the measured abundance of iron is equal to:
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| :<math>\left[\frac{Fe}{H}\right]\ =\ -1.07 \pm 0.01</math>
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| This value is the [[logarithm]] of the ratio of iron to hydrogen relative to the same ratio in the Sun. Thus the cluster has an abundance of iron equal to 8.5% of the iron abundance in the Sun. Based upon the abundance measurements, there is evidence that this cluster hosts two distinct stellar populations. Each of the populations is a group of stars that all formed at about the same time. Thus the cluster may have undergone at least two separate cycles of star formation.<ref name=aaa490_2/>
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| The [[Space velocity (astronomy)|space velocity]] components of this cluster are (U, V, W) = ({{nowrap|–57 ± 3}}, {{nowrap|–193 ± 22}}, {{nowrap|–8 ± 5}}) km/s. It is following an orbit through the [[Milky Way]] that has a period of {{nowrap|(116 ± 3) million years}} and an [[Orbital eccentricity|eccentricity]] of 0.80 ± 0.03. During [[periapsis]] it comes within {{nowrap|(0.6 ± 0.1) kpc}} from the Galactic core, while at [[apoapsis]] it travels out to a distance of {{nowrap|(5.9 ± 0.3) kpc}}. The orbital [[inclination]] is at an angle of {{nowrap|23° ± 6°}} from the galactic plane, carrying it as much as {{nowrap|(1.5 ± 0.4) kpc}} above the disk.<ref name=aj117_4/> When passing through the disk, this cluster does so at distances of less than 5 kpc from the [[galactic nucleus]]. The cluster undergoes [[tidal shock]] during each passage, which can cause the repeated shedding of stars. Thus the cluster may have been much more massive in the past.<ref name=aaa490_2/>
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| ==Notable stars==
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| Photographs taken with the [[Hubble Space Telescope]] in 1995 have revealed [[white dwarf]] stars in M4 that are among the oldest known stars in the [[Milky Way Galaxy]] at an age of 13 billion years. One such white dwarf has been found to be a [[binary star]] with a pulsar companion, [[PSR B1620-26]] and a [[PSR B1620-26 b|planet]] orbiting it with a mass of 2.5 times that of [[Jupiter mass|Jupiter]].
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| In 1987 a [[millisecond pulsar]] was discovered in M4 with a period of 3.0 [[millisecond]]s or about ten times faster than the [[Crab Pulsar]].
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| ==Gallery==
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| <gallery>
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| File:The globular star cluster Messier 4.jpg|One star in Messier 4 was also found to have much more of the rare light element lithium than expected.<ref>{{cite news|title=A Cluster with a Secret|url=http://www.eso.org/public/news/eso1235/|accessdate=5 September 2012|newspaper=ESO Press Release}}</ref>
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| File:Messier 4 HST.jpg|Messier 4 contains several tens of thousand stars and is noteworthy in being home to many [[white dwarf]]s.<ref>{{cite news|title=Ancient orbs|url=http://www.spacetelescope.org/images/potw1236a/|accessdate=3 September 2012|newspaper=ESA/Hubble Picture of the Week}}</ref>
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| File:M4HunterWilsonNew.jpg|[[Globular cluster]] '''Messier 4''' with amateur telescope.
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| </gallery>
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| ==References==
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| {{reflist|refs=
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| <ref name="simbad">{{cite web | title=M 4 – Globular Cluster | work=SIMBAD Astronomical Database | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=M+4 | accessdate=2010-03-25}}</ref>
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| <ref name=aj140_6_1830>{{Cite journal | 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 }}</ref>
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| <ref name=aaa143_1>{{cite journal | author=Caputo, F.; Castellani, V.; Quarta, M. L. | title=Reddening, distance modulus and age of the globular cluster NGC 6121 (M4) from the properties of RR Lyrae variables | journal=Astronomy and Astrophysics | volume=143| issue=1 |date=February 1985 | pages=8–12 | bibcode=1985A&A...143....8C | last2=Castellani | last3=Quarta | |
| }}</ref>
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| <ref name=aj117_4>{{cite journal | author=Dinescu, Dana I.; Girard, Terrence M.; van Altena, William F. | title=Space Velocities of Globular Clusters. III. Cluster Orbits and Halo Substructure | journal=The Astronomical Journal | volume=117| issue=4 | pages=1792–1815 |date=April 1999 | doi=10.1086/300807 | bibcode=1999AJ....117.1792D }}</ref>
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| <ref name=aaa490_2>{{cite journal | author=Marino, A. F. | coauthors=''et al.'' | title=Spectroscopic and photometric evidence of two stellar populations in the Galactic globular cluster NGC 6121 (M 4) | journal=Astronomy and Astrophysics | volume=490 | issue=2 | pages=625–640 |date=November 2008 | doi=10.1051/0004-6361:200810389 | bibcode=2008A&A...490..625M |arxiv = 0808.1414 }}</ref> | |
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| <ref name=hcob849_11>{{Cite journal | 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>
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| <ref name=mnras406_3_2000>{{Cite journal | last1=Marks | first1=Michael | last2=Kroupa | first2=Pavel | title=Initial conditions for globular clusters and assembly of the old globular cluster population of the Milky Way | journal=Monthly Notices of the Royal Astronomical Society | volume=406 | issue=3 | pages=2000–2012 |date=August 2010 | doi=10.1111/j.1365-2966.2010.16813.x | bibcode=2010MNRAS.406.2000M | postscript=. |arxiv = 1004.2255 }} Mass is from M<sub>PD</sub> on Table 1.</ref>
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| == External links ==
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| {{Commons category|Messier 4}}
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| * [http://www.seds.org/messier/m/m004.html M4, SEDS Messier pages]
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| * [http://gclusters.altervista.org/cluster_4.php?ggc=M+4 M4, Galactic Globular Clusters Database page]
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| * {{cite news | title=Hubble Space Telescope Finds Stellar Graveyard | publisher=Hubble News Desk | date=1995-08-28 | url=http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/32/text/ | accessdate=2006-05-24 }}
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| * {{cite web|last=Gray|first=Meghan|title=M4 – Globular Cluster|url=http://www.deepskyvideos.com/videos/messier/M4.html|work=Deep Sky Videos|publisher=[[Brady Haran]]}}
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| * {{WikiSky}}
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| {{Messier objects}}
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| {{Sky|16|23|35.41|-|26|31|31.9|7200}}
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| [[Category:Globular clusters|Messier 004]]
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| [[Category:Scorpius (constellation)|Messier 004]]
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| [[Category:Messier objects|004]]
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| [[Category:NGC objects|Messier 004]]
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| [[Category:Astronomical objects discovered in 1746]]
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| [[Category:Objects within 10 kly of Earth]]
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