View source for Messier 79

{{Short description|Globular cluster in constellation Lepus}}
{{Use dmy dates|date=June 2021}}
{{Infobox globular cluster
| name = [[Messier object|Messier]] 79
| image = [[Image:A snowstorm of stars.jpg|300px]]
| epoch = [[J2000]]
| class = V<ref name=hcob849_11/>
| constellation = [[Lepus constellation|Lepus]]
| ra = {{RA|05|24|10.59}}<ref name="simbad">
{{cite simbad
 | title=M 79
 | access-date=2006-11-17
}}</ref>
| dec = {{DEC|-24|31|27.3}}<ref name="simbad" />
| dist_ly = {{Convert|12.9|kpc|kly|abbr=on|lk=on}}<ref name=AJ112_1487/>
| appmag_v = 7.7<ref>{{cite web |url=https://messier.seds.org/m/m079.html |title=Messier 79 |access-date=30 April 2022 |website=SEDS Messier Catalog}}</ref>
| size_v = 8.7'
| mass_kg = 
| mass_msol = 
| radius_ly = 53&nbsp;[[light-year|ly]]<ref>distance × sin( diameter_angle / 2 ) = 53 ly. radius</ref>
| v_hb = 
| age = 11.7&nbsp;[[Gigayear|Gyr]]<ref name=mnras385_4_1998/>
| metal_fe = –1.55<ref name=mnras385_4_1998/>
| notes = 
| names = M79, [[New General Catalogue|NGC]] 1904, GCl 10, [[Melotte catalogue|Melotte]] 34<ref name="simbad" />
}}

'''Messier 79''' (also known as '''M79'''<ref>Abbreviated Messier</ref> or '''NGC 1904''') is a [[globular cluster]] in the southern [[Lepus constellation|constellation Lepus]]. It was discovered by [[Pierre Méchain]] in 1780 and is about 42,000 [[light-year]]s away from [[Earth]] and 60,000 light years from the [[Galactic Center]].

Like [[Messier 54]] (the other extragalactic globular on [[Messier object|Messier's list]]), it is believed to not be native to the [[Milky Way]] galaxy at all, but instead to the putative [[Canis Major Dwarf Galaxy]], which is currently experiencing a very close encounter with our galaxy. This is, however, a contentious subject as astronomers are still debating the nature of the Canis Major dwarf galaxy itself.<ref>
{{cite journal
 |author=López-Corredoira, M.
 |author2=Momany, Y.
 |author3=Zaggia, S.
 |author4=Cabrera-Lavers, A.
 |date=2007
 |title=Re-affirming the connection between the Galactic stellar warp and the Canis Major over-density
 |journal=[[Astronomy & Astrophysics]]
 |volume=472 |issue=3 |pages=L47–L50
 |arxiv=0707.4440
 |bibcode=2007A&A...472L..47L
 |doi=10.1051/0004-6361:20077813
|s2cid=17662347
 }}</ref> Messier 79 may also be part of the [[Gaia Sausage]].<ref name=Myeong_etal>{{cite journal |last1=Myeong |first1=G.C.
 |last2=Evans |first2=N.W.
 |last3=Belokurov |first3=V.
 |last4=Sanders |first4=J.L.
 |last5=Koposov |first5=S.
 |title=The Sausage globular clusters
 |journal=The Astrophysical Journal |volume=863 |issue=2 |pages=L28
 |date=2018|bibcode=2018ApJ...863L..28M |arxiv=1805.00453 |doi=10.3847/2041-8213/aad7f7|s2cid=67791285
 |doi-access=free
 }}</ref>

The cluster is being disrupted by the [[galactic tide]], trailing a long [[tidal tail]].<ref>{{citation|arxiv=1710.08927|year=2017|title=Tails and streams around the Galactic globular clusters NGC 1851, NGC 1904, NGC 2298 and NGC 2808|doi=10.1093/mnras/stx2767 |last1=Carballo-Bello |first1=Julio A. |last2=Martínez-Delgado |first2=David |last3=Navarrete |first3=Camila |last4=Catelan |first4=Márcio |last5=Muñoz |first5=Ricardo R. |last6=Antoja |first6=Teresa |last7=Sollima |first7=Antonio |journal=Monthly Notices of the Royal Astronomical Society |volume=474 |pages=683–695 |doi-access=free }}</ref>

==Color-magnitude diagram==
[[File:Infrared color magnitude diagram of Messier 79.png|left|thumb|An infrared color-magnitude diagram of Messier 79]]
This [[Hertzsprung–Russell diagram|color-magnitude diagram]] was made using near-infrared images of the cluster in [[Photometric system#Photometric letters|J and K bands]]. J-band magnitude is plotted along the y-axis and J to K dominant color is plotted along the x-axis. Such a diagram is made rapidly with specialized code for crowded-field photometry.<ref>This diagram was made by [[Astromundus]] students attending lectures and a workshop by Peter Stetson, the writer of DAOPHOT, standard code for crowded-field photometry. Date: June 2011, [[University of Rome Tor Vergata]]</ref>

From this, it is evident that most of the bright stars in this cluster are red giants. The elongated branch is the [[red giant branch]]. Some of the stars in the diagram, including those extending outward from the red giant branch toward the upper left, are actually foreground stars that are not members of the cluster.

Altogether three regions of the [[Hertzsprung–Russell diagram]] are present here: the low-mass end of the [[main sequence]], the complete red giant branch and the [[horizontal branch]]. Compared to optical bands, in infrared bands the lower main sequence is shallower and the horizontal branch is steeper (the blue end is fainter and the red end is brighter).
{{clear}}

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

==References==
{{Reflist|2|refs=

<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 }}</ref>

<ref name=AJ112_1487>{{citation | last1=Harris | first1=William E. | title=A New Catalog of Globular Clusters in the Milky Way | date=December 2010 | url=http://physwww.mcmaster.ca/~harris/mwgc.dat | bibcode=2010arXiv1012.3224H |arxiv = 1012.3224 }}</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>

}}

==External links==
{{Commons category}}
* [http://messier.seds.org/m/m079.html Messier 79, SEDS Messier pages]
* [http://gclusters.altervista.org/cluster_4.php?ggc=M+79 Messier 79, Galactic Globular Clusters Database page]
* {{WikiSky}}

{{Portal bar|Astronomy|Stars|Outer space}}
{{Messier objects}}
{{NGC20}}
{{Lepus (constellation)}}

{{Sky|05|24|10.59|-|24|31|27.3|41000}}

{{DEFAULTSORT:Messier 79}}
[[Category:Globular clusters|Messier 079]]
[[Category:Canis Major Overdensity|Messier 079]]
[[Category:Lepus (constellation)|Messier 079]]
[[Category:Messier objects|079]]
[[Category:NGC objects|Messier 079]]
[[Category:Astronomical objects discovered in 1780]]
[[Category:Discoveries by Pierre Méchain]]