{{Short description|Type-cD galaxy in the constellation Draco}} {{Infobox galaxy|name=[[Abell 2218]] BCG|epoch=[[J2000.0]]|constellation name=[[Draco (constellation)|Draco]]|ra={{RA|16|35|49.12}}<ref name="ned" />|dec={{DEC|+66|12|33.88}}<ref name="ned" />|z=0.172000<ref name="ned" />|h_radial_v=51,564 ± 120 [[kilometer per second|km/s]]<ref name="ned" />|dist_ly={{convert|763.25 ± 53.49|Mpc|Mly|abbr=on|lk=on|order=flip}}<ref name="ned" />|group_cluster=[[Abell 2218]]|mag_j=15.17<ref name="ned" />|type=cD;E<ref name="ned" />|size=~{{convert|183.9|kpc|ly|abbr=on|lk=on|order=flip}} (estimated){{r|ned}}|names=[[2MASX]] J16354949+6612360, [[Abell 2218]]:[BOW83] 008, [[Lyon-Meudon Extragalactic Database|LEDA]] 140648, 2MFGC 13294, [HMD2010] J163549.1+661233.9<ref name="ned" />|image=File:Image of Abell 2218 BCG.png|caption=[[Pan-STARRS]] image of Abell 2218 BCG}}
'''Abell 2218 BCG''' (Short for '''Abell 2218 Brightest Cluster Galaxy''') is a massive [[elliptical galaxy]] of [[Type-cD galaxy|type-cD]] located in the constellation of [[Draco (constellation)|Draco]]. The [[redshift]] of the galaxy is (z) 0.172<ref name="ned">{{Cite web |title=NED Search results for Abell 2218 BCG (LEDA 140648) |url=https://ned.ipac.caltech.edu/byname?objname=LEDA+140648&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1 |access-date=2026-05-15 |website=NASA/IPAC Extragalactic Database}}</ref> and it was first discovered in January 1988 by astronomers who noted curved structures around it.<ref name=":0">{{Cite web |last1=Pello-Descayre |first1=R. |last2=Soucail |first2=G. |last3=Sanahuja |first3=B |last4=Mathez |first4=G. |last5=Ojero |first5=E. |date=January 1988 |title=Detection and photometry of a complex system in the center of the A 2218 cluster of galaxies. |url=https://articles.adsabs.harvard.edu/pdf/1988A%26A...190L..11P |access-date=2026-05-15 |website=ui.adsabs.harvard.edu}}</ref> It is the [[brightest cluster galaxy]] of [[Abell 2218]], a luminous [[Bautz–Morgan classification|Bautz-Morgan]] class II [[galaxy cluster]].<ref>{{Cite journal |last1=Egami |first1=E. |last2=Misselt |first2=K. A. |last3=Rieke |first3=G. H. |last4=Wise |first4=M. W. |last5=Neugebauer |first5=G. |last6=Kneib |first6=J.-P. |last7=Le Floc’h |first7=E. |last8=Smith |first8=G. P. |last9=Blaylock |first9=M. |last10=Dole |first10=H. |last11=Frayer |first11=D. T. |last12=Huang |first12=J.-S. |last13=Krause |first13=O. |last14=Papovich |first14=C. |last15=Perez-Gonzalez |first15=P. G. |date=2006-08-20 |title=''Spitzer'' Observations of the Brightest Galaxies in X-Ray-Luminous Clusters |journal=The Astrophysical Journal |volume=647 |issue=2 |pages=922–933 |doi=10.1086/504519 |arxiv=astro-ph/0603656 |bibcode=2006ApJ...647..922E |issn=0004-637X}}</ref><ref name=":1">{{Cite journal |last1=McHardy |first1=I. M. |last2=Stewart |first2=G. C. |last3=Edge |first3=A. C. |last4=Cooke |first4=B. |last5=Yamashita |first5=K. |last6=Hatsukade |first6=I. |date=January 1990 |title=GINGA observations of Abell 2218: implications for H0 |url=https://articles.adsabs.harvard.edu/pdf/1990MNRAS.242..215M |journal=Monthly Notices of the Royal Astronomical Society |volume=242 |issue=2 |pages=215–220 |doi=10.1093/mnras/242.2.215 |doi-access=free |issn=0035-8711}}</ref>
== Description == Abell 2218 BCG is the central dominant galaxy of Abell 2218.<ref name=":1" /><ref name=":2">{{Cite journal |last1=Rafferty |first1=D. A. |last2=McNamara |first2=B. R. |last3=Nulsen |first3=P. E. J. |date=2008-11-10 |title=The Regulation of Cooling and Star Formation in Luminous Galaxies by Active Galactic Nucleus Feedback and the Cooling-Time/Entropy Threshold for the Onset of Star Formation |journal=The Astrophysical Journal |volume=687 |issue=2 |pages=899–918 |doi=10.1086/591240 |arxiv=0802.1864 |bibcode=2008ApJ...687..899R |issn=0004-637X}}</ref> The galaxy has a low [[surface brightness]] central profile and a single nucleus. Its galactic envelope is best described by a [[De Vaucouleurs's law|de Vaucouleurs law]] profile and is more than 180 [[Parsec|kiloparsecs]] in length.<ref name=":3">{{Cite journal |last1=Kneib |first1=J. P. |last2=Y. |first2=Mellier |last3=Pello |first3=R. |last4=Miralda-Escude |first4=J. |last5=Le Borgne |first5=J.-F. |last6=Boehringer |first6=H. |last7=Picat |first7=J.-P. |date=November 1995 |title=Dynamics of Abell 2218 from optical and near-IR imagery of arc(let)s and the ROSAT/HRI X-ray map. |journal=Astronomy and Astrophysics |volume=303 |page=27 |arxiv=astro-ph/9504038 |bibcode=1995A&A...303...27K }}</ref><ref name=":0" /> The [[Flattening|ellipticity]] increases in an outward direction with the isothopes in the innermost region at the [[radius]] of one arcsecond depicted as circularized. The BCG's [[Semi-major and semi-minor axes|major axis]] decreases along with its radius, with the twist angle being around 8°.<ref name=":3" />
The total [[stellar population]] of the BCG is estimated to be aged 9.8 ± 2.8 billion years, with a [[stellar mass]] of 102.1 ± 2.6 × 10<sup>10</sup> M<sub>ʘ</sub>.<ref>{{Cite journal |last1=Sánchez |first1=S. F. |last2=Cardiel |first2=N. |last3=Verheijen |first3=M. A. W. |last4=Pedraz |first4=S. |last5=Covone |first5=G. |date=2007-03-21 |title=Morphologies and stellar populations of galaxies in the core of Abell 2218 |journal=Monthly Notices of the Royal Astronomical Society |volume=376 |issue=1 |pages=125–150 |doi=10.1111/j.1365-2966.2007.11335.x |doi-access=free |arxiv=astro-ph/0611660 |bibcode=2007MNRAS.376..125S |issn=0035-8711}}</ref> The U – R color is 0.02 ± 0.10 [[Magnitude (astronomy)|magnitude]] with a U – R [[color gradient]] of -0.41 ± 0.11 magnitude per dex<sup>-1</sup>.<ref name=":2" /> A study published in July 1999, has found the [[Visible spectrum|optical spectrum]] of the BCG shows the absence of [[Spectral line|emission lines]].<ref>{{Cite journal |last1=Crawford |first1=C. S. |last2=Allen |first2=S. W. |last3=Ebeling |first3=H. |last4=Edge |first4=A. C. |last5=Fabian |first5=A. C. |date=1999-07-11 |title=The ROSAT Brightest Cluster Sample -- III. Optical spectra of the central cluster galaxies |journal=Monthly Notices of the Royal Astronomical Society |volume=306 |issue=4 |pages=857–896 |doi=10.1046/j.1365-8711.1999.02583.x |doi-access=free |arxiv=astro-ph/9903057 |bibcode=1999MNRAS.306..857C |issn=0035-8711}}</ref> The central core of the BCG has a red appearance based on its inner color profile shape with the r' best surface brightness profile parameter being 23.60<sup>+0.14</sup><sub>-0.17</sub> magnitude.<ref>{{Cite journal |last1=Bildfell |first1=Chris |last2=Hoekstra |first2=Henk |last3=Babul |first3=Arif |last4=Mahdavi |first4=Andisheh |date=2008-08-26 |title=Resurrecting the red from the dead: optical properties of BCGs in X-ray luminous clusters |journal=Monthly Notices of the Royal Astronomical Society |volume=389 |issue=4 |pages=1637–1654 |doi=10.1111/j.1365-2966.2008.13699.x |doi-access=free |arxiv=0802.2712 |bibcode=2008MNRAS.389.1637B |issn=0035-8711}}</ref>
There are two faint resolved arc structures extending from east to west around the BCG. The first arc is the brightest, with a [[curvature]] radius of 130 ± 20 kiloparsecs and is located from the center. The second arc is faint, with both a bright part and a faint extension. This faint arc has a curvature radius of 100 kiloparsecs and is situated 20 kiloparsecs from the BCG's center from south to east.<ref name=":0" />
== References == <references />
== External links == {{WikiSky}}
{{Draco (constellation)}} [[Category:Elliptical galaxies]] [[Category:Draco (constellation)]] [[Category:LEDA objects|140648]] [[Category:Astronomical objects discovered in 1988]]