View source for Terzan 7

{{Infobox globular cluster
| name = Terzan 7
| image = [[Image:It came from outer space.jpg|250px]]
| caption = Terzan7 by [[Hubble Space Telescope]]; 3.5{{prime}} view
| credit = 
| epoch = [[Epoch (astronomy)#Julian years and J2000|J2000]]
| class = 
| constellation = [[Sagittarius (constellation)|Sagittarius]]
| ra = {{RA|19|17|43.92}}<ref name=aj140_6_1830/>
| dec = {{DEC|-34|39|27.8}}<ref name=aj140_6_1830/>
| dist_ly = {{Convert|75.7|kly|kpc|abbr=on|lk=on}}<ref name="seds">{{citation
 |title       = Terzan 7 @ seds
 |url         = http://www.seds.org/~spider/spider/MWGC/ter07.html
 |url-status     = dead
 |archiveurl  = https://web.archive.org/web/20021024065203/http://www.seds.org/~spider/spider/MWGC/ter07.html
 |archivedate = 2002-10-24
}}</ref>
| appmag_v = 12.0<ref name="seds" />
| size_v = 7.3{{prime}}<ref name="seds" />
| mass_msol = 
| radius_ly = 160&nbsp;[[light year|ly]]{{Ref_label|A|a|none}}
| v_hb = 17.76<ref name="Wilson1995">{{citation
 | last1 = Wilson
 | first1 = Barbara
 | date = July 2, 1995
 | title = Obscure Globulars
 | url = http://www.astronomy-mall.com/Adventures.In.Deep.Space/obscure.htm
}}</ref>
| age = [[1 E17 s|7.5 Gyr]]<ref name="Geisleretal2007">{{citation
 | last1 = Geisler
 | first1 = Doug
 | last2 = Wallerstein
 | first2 = George
 | last3 = Smith
 | first3 = Verne V.
 | last4 = Casetti-Dinescu
 | first4 = Dana I.
 | title = Chemical Abundances and Kinematics in Globular Clusters and Local Group Dwarf Galaxies and Their Implications for Formation Theories of the Galactic Halo
 
 | date = September 2007
 | journal = The Publications of the Astronomical Society of the Pacific
 | volume = 119
 | issue = 859
 | pages = 939–961
 | bibcode = 2007PASP..119..939G
 | doi = 10.1086/521990
|arxiv = 0708.0570 | s2cid = 119599242
 }}</ref>
| notes = young extragalactic globular
| names = Ter 7,<ref name="Geisleretal2007" /> GCl 109.1<ref name="simbad" />
}}

'''Terzan&nbsp;7''' is a sparse and young [[globular cluster]] that is believed to have originated in the [[Sagittarius Dwarf Spheroidal Galaxy]] (Sag DEG) and is physically associated with it. It is relatively [[metallicity|metal rich]] with {{Fe/H|link=y|-0.6}}<ref name ="Sbordoneetal2005">{{citation
 | last1 = Sbordone
 | first1 = L.
 | last2 = Bonifacio
 | first2 = P.
 | last3 = Marconi
 | first3 = G.
 | last4 = Buonanno
 | first4 = R.
 | last5 = Zaggia
 | first5 = S.
 | title = Family ties: Abundances in Terzan 7, a Sgr dSph globular cluster
 | date = July 3, 2005
 | journal = Astronomy and Astrophysics
 | volume = 437
 | issue = 3
 | pages = 905–910
 | bibcode = 2005A&A...437..905S
 | doi = 10.1051/0004-6361:20042315
|arxiv = astro-ph/0505307 | s2cid = 11063189
 }}</ref> and an estimated age of 7.5 [[Byr|Gyr]].<ref name="Geisleretal2007" /> Terzan&nbsp;7 has low levels of [[nickel]] ([Ni/Fe] = -0.2) which supports its membership in the Sag DEG system since it has a similar chemical signature.<ref name ="Sbordoneetal2004">{{citation
 | last1 = Sbordone
 | first1 = L.
 | last2 = Bonifacio
 | first2 = P.
 | last3 = Marconi
 | first3 = G.
 | last4 = Buonanno
 | first4 = R.
 | date = 2004
 | title = Chemical abundances in Terzan 7
 | journal = Memorie della Societa Astronomica Italiana
 | volume = 75
 | page = 396
 | bibcode = 2004MmSAI..75..396S
}}</ref> It has a rich population of [[blue straggler]]s that are strongly concentrated toward the center of Terzan&nbsp;7.<ref name="Heldetal2001">{{citation
 | last1 = Held
 | first1 = Enrico V.
 | last2 = Rosenberg
 | first2 = Alfred
 | last3 = Saviane
 | first3 = Ivo
 | last4 = Momany
 | first4 = Yazan
 | title = The Globular Cluster Terzan 7 in the Sagittarius Dwarf Spheroidal Galaxy
 | journal = Extragalactic Star Clusters
 | volume = 207
 | publisher=Astronomical Society of the Pacific
 | location = Pucon, Chile
 | date = March 12–16, 2001
 | editor1-first = D.
 | editor2-last = Grebel
 | editor2-first = E.K.
 | editor3-last = Minniti
 | editor3-first = D.
 | publication-date = 2002
 | publication-place = San Francisco
 | page = 165
 | bibcode = 2002IAUS..207..165H
 | editor-last = Geisler
}}</ref> It has an average luminosity distribution of M<sub>v</sub> = -5.05.<ref name="Bergh2007">{{citation
 | last1 = van den Bergh
 | first1 = Sidney
 | authorlink1 = Sidney van den Bergh
 
 | date = July 2007
 | title = The Luminosity Distribution of Globular Clusters in Dwarf Galaxies
 | journal = The Astronomical Journal
 | volume = 134
 | issue = 1
 | pages = 344–345
 | bibcode = 2007AJ....134..344V
 | doi = 10.1086/518868
|arxiv = 0704.2226 | s2cid = 14209616
 }}</ref> It has a [[Effective radius|half-light radius]] (R<sub>h</sub>) of 6.5pc.<ref name="Bergh2000">{{citation
 | last1 = van den Bergh
 | first1 = Sidney
 | authorlink1 = Sidney van den Bergh
 | title = Young Globular Clusters and Dwarf Spheroidals
 
 | date = February 2000
 | journal = The Astrophysical Journal
 | volume = 530
 | issue = 2
 | pages = 777–782
 | bibcode = 2000ApJ...530..777V
 | doi = 10.1086/308413
|arxiv = astro-ph/9910243 | s2cid = 14218931
 | url = https://cds.cern.ch/record/403506/files/9910243.pdf
 }}</ref>

==History==
Terzan&nbsp;7 was the brightest<ref name="skyandtelescope2000" /> of six globulars discovered by Turkish-Armenian<ref name="skyandtelescope2000">{{citation
 | title = 
 | last1 = Gottlieb
 | first1 = Steve
 | journal = Sky and Telescope
 | volume = 100
 | issue = 2
 | issn = 0037-6604
 | page = 112
 | date = August 1, 2000
}}</ref> astronomer [[Agop Terzan]] in 1968.<ref name="Terzan1968">{{citation
 | last1 = Terzan
 | first1 = Agop
 | date = 1968
 | title = Six nouveaux amas stellaires (Terzan 3-8) dans la region DU centre de la Voie lactee et les constellations DU Scorpion et DU Sagittaire
 | journal = C. R. Acad. Sci.
 | issue = Ser. B
 | volume = 267
 | pages = 1245–1248
 | bibcode = 1968CRASB.267.1245T
}}</ref>

==Young globular==
Nearly all globular clusters of the [[Milky Way]]'s [[galactic halo]] formed at the same time (12-15 Gyr). Even the far situated [[NGC 2419]] (~100 kpc from [[Galactic Center]]) has a similar age. This trend also applies to the age of globulars found in the [[Large Magellanic Cloud]] and [[Fornax Dwarf]] (~140 kpc from Galactic Center). However, a few globulars seem to be significantly younger than the rest; these include [[Palomar 1]], [[Palomar 3]], [[Palomar 4]], [[Palomar 12]], [[Palomar 14]], [[Ruprecht 106]], [[IC 4499]], [[Arp 2]], [[Eridanus (globular cluster)|Eridanus]], [[Fornax 4]], and Terzan 7. In particular, the ones associated with the Sag DEG appear to have formed more recently. The data suggests that all the present outer halo globulars may have originally formed in dwarf spheroidals.<ref name="Bergh2000" />

===Hierarchical galaxy formation===
Alternatively, a hierarchical galaxy formation model is hypothesized under which a portion, possibly large, of the Milky Way's globular clusters would have originated in the [[Accretion (astrophysics)|accretion]] of other [[dwarf spheroidal galaxy|dwarf spheroidals]] like Sag DEG.  The best candidate for this idea is [[Palomar 12|Palomar&nbsp;12]].<ref name ="Sbordoneetal2005" /><ref name ="Briley2007">{{citation
 | last1 = Briley
 | first1 = Michael M.
 | last2 = Martell
 | first2 = S.
 | last3 = Smith
 | first3 = G. H.
 | title = The Homogeneity of Light Elements in the Sagittarius Elliptical Dwarf Galaxy Globular Clusters Terzan 7 and Arp 2
 
 | date = December 2007
 | journal = American Astronomical Society, AAS Meeting #211, #58.31
 | volume = 211
 | pages = 58.31
 | bibcode = 2007AAS...211.5831B
}}</ref>

==Notes==
{{refbegin}}
<ol type="a">
<li>{{Note_label|A|a|none}}75.7 kly × tan( 7.3{{prime}} / 2 ) = 160 ly. radius</li>
</ol>
{{refend}}

==References==
{{Reflist|30em|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="simbad">{{cite simbad | title=Cl Terzan 7 | accessdate=2008-01-27}}</ref>

}}

{{sky|19|17|43.5|-|34|39|27|75700}}

{{Milky Way}}

{{DEFAULTSORT:Terzan 07}}
[[Category:Globular clusters]]
[[Category:Sagittarius Dwarf Spheroidal Galaxy]]
[[Category:Sagittarius (constellation)]]
[[Category:Astronomical objects discovered in 1968|?]]