Editing Messier 9

{{short description|Globular cluster in Ophiuchus}}
{{Infobox globular cluster
| name = Messier 9
| image = [[Image:Globular cluster Messier 9 (captured by the Hubble Space Telescope).tif|250px]]
| caption = Messier 9 by [[Hubble Space Telescope|HST]]
| credit = 
| epoch = [[J2000]]
| class = VIII<ref name=hcob849_11/>
| constellation = [[Ophiuchus]]
| ra = {{RA|17|19|11.78}}<ref name=mnras332_2_441/>
| dec = {{DEC|–18|30|58.5}}<ref name=mnras332_2_441/>
| dist_ly = {{Convert|25.8|kly|kpc|abbr=on|lk=on}}<ref name=apj742_1_51/>
| appmag_v = 7.7<ref>{{cite web |url=http://www.messier.seds.org/m/m009.html |title=Messier 9 |access-date=21 July 2024 |website=SEDS Messier Catalog}}</ref>
| size_v = 9.3′<ref name="Gilmour2012"/>
| mass_msol = {{Val|4.22|e=5}}<ref name=apj742_1_51/>
| radius_ly = 45&nbsp;ly<ref name=apj742_1_51/>
| metal_fe = –1.77<ref name=apj742_1_51/>
| v_hb = 
| age = 12.0&nbsp;[[Gigayear|Gyr]]<ref name=mnras385_4_1998/>
| notes = 
| names = [[Henry Draper catalogue|HD]] 156587, [[New General Catalogue|NGC]] 6333<ref name="simbad" />
}}

'''Messier 9''' or '''M9''' (also designated '''NGC 6333''') is a [[globular cluster]] in the [[constellation]] of [[Ophiuchus]]. It is positioned in the southern part of the constellation to the southwest of [[Eta Ophiuchi]], and lies atop a dark cloud of dust designated Barnard 64.<ref name="Gilmour2012"/><ref name="OMeara2014"/> The cluster was discovered by French astronomer [[Charles Messier]] on June 3, 1764, who described it as a "nebula without stars".<ref name="Machholz2002"/> In 1783, English astronomer [[William Herschel]] was able to use his reflector to resolve individual stars within the cluster. He estimated the cluster to be 7&ndash;8[[arcminutes|′]] in diameter with stars densely packed near the center.<ref name="Klein1901"/>

M9 has an [[apparent magnitude]] of 7.9, an angular size of 9.3′, and can be viewed with a small [[telescope]].<ref name="Gilmour2012"/> It is one of the nearer globular clusters to the center of [[Milky Way Galaxy|the galaxy]] as is around 5,500 [[light-year]]s from the [[Galactic Center]]. Its distance from [[Earth]] is 25,800 light-years.

The total [[luminosity]] of this cluster is around 120,000 times that of the [[Sun]], the [[absolute magnitude]] being -8.04. The brightest individual [[star]]s in M9 are of [[apparent magnitude]] 13.5, making them visible in moderately sized [[telescope]]s. There have been 24 [[variable star]]s found in M9: 21 [[RR Lyrae variable]]s, plus a [[Long-period variable star|long-period variable]], [[Type II Cepheid]], and an [[Algol variable|eclipsing binary]]. No [[blue straggler]]s or [[SX Phoenicis variable]]s have been discovered. Based upon the periods of the RR Lyr variables, this cluster is classified as an Oosterhoff type II globular, which precludes an extra-galactic origin.<ref name=mnras434_2_1220/>

At about 80' ({{frac|1|1|3}} degrees) to the northeast of M9 is the dimmer globular cluster [[NGC 6356]], while about the same to the southeast is the globular [[NGC 6342]].

==Gallery==

<gallery>
File:Messier object 009.jpg|Messier 9, from ''[[2MASS]]''
File:M9map.png|Map showing the location of Messier 9
</gallery>

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

==References==

{{Reflist|refs=

<ref name="simbad">{{cite simbad | title=M 9 | access-date=2006-11-15}}</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 | volume=849 | issue=849 | pages=11–14 |date=August 1927 | bibcode=1927BHarO.849...11S | postscript=. }}</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>

<ref name=mnras385_4_1998>{{citation | display-authors=1 | last1=Koleva | first1=M. | last2=Prugniel | first2=Ph. | last3=Ocvirk | first3=P. | last4=Le Borgne | first4=D. | last5=Soubiran | first5=C. | title=Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=385 | issue=4 | pages=1998–2010 |date=April 2008 | doi=10.1111/j.1365-2966.2008.12908.x | doi-access=free | bibcode=2008MNRAS.385.1998K |arxiv = 0801.0871 | s2cid=17571531 }}</ref>

<ref name="Machholz2002">{{citation
 | first1=Don | last1=Machholz
 | title=The Observing Guide to the Messier Marathon: A Handbook and Atlas
 | page=23 | year=2002 | publisher=[[Cambridge University Press]] | isbn=978-0521803861
 | url=https://books.google.com/books?id=iGI1wjkGLkQC&pg=PA23
 | postscript=. }}</ref>

<ref name="Klein1901">{{citation
 | first1=Hermann Joseph | last1=Klein | title=Star Atlas
 | page=55 | year=1901 | publisher=Society for promoting Christian knowledge
 | url=https://books.google.com/books?id=XszaAAAAMAAJ&pg=PA55
 | postscript=. }}</ref>

<ref name="Gilmour2012">{{citation
 | first1=Jess K. | last1=Gilmour
 | title=The Practical Astronomer's Deep-sky Companion
 | series=The Patrick Moore Practical Astronomy Series
 | page=75 | publisher=Springer Science & Business Media | year=2012
 | url=https://books.google.com/books?id=HyMRBwAAQBAJ&pg=PA75
 | isbn=978-1447100713 | postscript=. }}</ref>

<ref name="OMeara2014">{{citation
 | first1=Stephen James | last1=O'Meara
 | title=Deep-Sky Companions: The Messier Objects
 | page=71 | publisher=Cambridge University Press | year=2014
 | url=https://books.google.com/books?id=fDQZAwAAQBAJ&pg=PA71
 | isbn=978-1107018372 | postscript=. }}</ref>

<ref name=mnras332_2_441>{{citation
 | display-authors=1 | last1=Formiggini | first1=Liliana
 | last2=Brosch | first2=Noah | last3=Almoznino | first3=Elchanan
 | last4=Bowyer | first4=Stuart | last5=Lampton | first5=Michael 
 | title=Hidden subluminous stars among the FAUST UV sources towards Ophiuchus 
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=332 | issue=2 | pages=441–455 | date=May 2002
 | doi=10.1046/j.1365-8711.2002.05327.x | doi-access=free | bibcode=2002MNRAS.332..441F
 | arxiv=astro-ph/0210325 | s2cid=119462293 | postscript=. }}</ref>

<ref name=mnras434_2_1220>{{citation
 | display-authors=1 | last1=Arellano Ferro | first1=A.
 | last2=Bramich | first2=D. M. | last3=Figuera Jaimes | first3=R.
 | last4=Giridhar | first4=Sunetra | last5=Kains | first5=N.
 | last6=Kuppuswamy | first6=K. | last7=Jørgensen | first7=U. G.
 | last8=Alsubai | first8=K. A. | last9=Andersen | first9=J. M.
 | last10=Bozza | first10=V. | last11=Browne | first11=P.
 | last12=Calchi Novati | first12=S. | last13=Damerdji | first13=Y.
 | last14=Diehl | first14=C. | last15=Dominik | first15=M.
 | last16=Dreizler | first16=S. | last17=Elyiv | first17=A.
 | last18=Giannini | first18=E. | last19=Harpsøe | first19=K.
 | last20=Hessman | first20=F. V. | last21=Hinse | first21=T. C.
 | last22=Hundertmark | first22=M. | last23=Juncher | first23=D.
 | last24=Kerins | first24=E. | last25=Korhonen | first25=H.
 | last26=Liebig | first26=C. | last27=Mancini | first27=L.
 | last28=Mathiasen | first28=M. | last29=Penny | first29=M. T.
 | last30=Rabus | first30=M. | last31=Rahvar | first31=S.
 | last32=Ricci | first32=D. | last33=Scarpetta | first33=G.
 | last34=Skottfelt | first34=J. | last35=Snodgrass | first35=C.
 | last36=Southworth | first36=J. | last37=Surdej | first37=J.
 | last38=Tregloan-Reed | first38=J. | last39=Vilela | first39=C.
 | last40=Wertz | first40=O. | last41=Mindstep Consortium 
 | title=A detailed census of variable stars in the globular cluster NGC 6333 (M9) from CCD differential photometry
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=434 | issue=2 | pages=1220–1238 | date=September 2013
 | doi=10.1093/mnras/stt1080 | doi-access=free | bibcode=2013MNRAS.434.1220A 
 | arxiv=1306.3206 | postscript=. }}</ref>

}}

==External links==
{{commonscat}}
* [http://www.messier.seds.org/m/m009.html Messier 9, SEDS Messier pages]
* [http://gclusters.altervista.org/cluster_4.php?ggc=M+9 M9, Galactic Globular Clusters Database page]
* [http://www.tgdaily.com/space-features/62135-the-glittering-stars-of-messier-9 The glittering stars of Messier 9], March 16, 2012, Tg Daily Staff, ''TG Daily''
* {{APOD |date=23 March 2012|title=Messer 9 Close Up}}
* {{WikiSky}}


{{Sky|17|19|11.78|-|18|30|58.5|25800}}
{{Portal bar|Astronomy|Stars|Outer space}}
{{Catalogs|M=9|NGC=6333|HD=156587}}
{{Messier objects}}
{{Ngc65}}

[[Category:Globular clusters|Messier 009]]
[[Category:Ophiuchus|Messier 009]]
[[Category:Messier objects|009]]
[[Category:NGC objects|Messier 009]]
[[Category:Astronomical objects discovered in 1764|17640528]]
[[Category:Discoveries by Charles Messier]]