{{Short description|Radio galaxy located in the constellation Draco}} {{Infobox galaxy|name=Goldfish galaxy|epoch=[[J2000.0]]|constellation name=[[Draco (constellation)|Draco]]|ra={{RA|17|13|03.78}}<ref name="ned" />|dec={{DEC|+64|07|01.71}}<ref name="ned" />|z=0.080923<ref name="ned" />|h_radial_v=24,260 [[kilometer per second|km/s]] ± 4<ref name="ned" />|dist_ly={{convert|360.67 ± 25.25|Mpc|Mly|abbr=on|lk=on|order=flip}}|group_cluster=[[Abell 2255]]|mag_j=13.48<ref name="ned" />|type=Radio galaxy<ref name="ned" />|size=~{{convert|58.9|kpc|ly|abbr=on|lk=on|order=flip}} (estimated){{r|ned}}|names=14W 118, [[Seventh Cambridge Survey|7C]] 1713+6407a, ABELL 2255:[DMM2003] 2, [[Principal Galaxies Catalogue|PGC]] 59858, [[Sloan Digital Sky Survey|SDSS]] J171303.78+640701.6, [[2MASX]] J17130384+6407014<ref name="ned" />|image=File:Image of Goldfish galaxy.png|caption=[[Sloan Digital Sky Survey|SDSS]] image of the Goldfish galaxy}}
The '''Goldfish galaxy''', also known as '''7C 1713+6407a''', is a [[radio galaxy]] located in the constellation of [[Draco (constellation)|Draco]]. The [[redshift]] of the galaxy is z=0.080<ref name="ned">{{Cite web |title=NED Search results for Goldfish galaxy |url=https://ned.ipac.caltech.edu/byname?objname=LEDA+59858&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1 |access-date=2026-02-14 |website=NASA/IPAC Extragalactic Database}}</ref> and it was first discovered by [[Astronomer|astronomers]] in 1974 as an [[astronomical radio source]] whom they described it having a steep [[radio spectrum]].<ref>{{Cite journal |last1=Slingo |first1=A. |last2=Baldwin |first2=J. E. |date=1974-08-01 |title=The Structure and Origin of Radio Sources with Very Steep Spectra |journal=Monthly Notices of the Royal Astronomical Society |volume=168 |issue=2 |pages=307–330 |doi=10.1093/mnras/168.2.307 |doi-access=free |issn=0035-8711}}</ref> It is considered to be a member of the rich [[galaxy cluster]] [[Abell 2255]], alongside the [[Beaver galaxy]], the [[Embryo galaxy]], the [[Original TRG]], and the [[Bean galaxy|Bean Galaxy]].<ref name=":0">{{Cite journal |last1=Davis |first1=David S. |last2=Miller |first2=Neal A. |last3=Mushotzky |first3=Richard F. |date=November 2003 |title=Chandra Observations of Point Sources in A2255 |url=https://ui.adsabs.harvard.edu/abs/2003ApJ...597..202D/abstract |journal=The Astrophysical Journal |language=en |volume=597 |issue=1 |pages=202–209 |doi=10.1086/378384 |arxiv=astro-ph/0307370 |bibcode=2003ApJ...597..202D |issn=0004-637X |archive-url=http://web.archive.org/web/20220629104758/https://ui.adsabs.harvard.edu/abs/2003ApJ...597..202D/abstract |archive-date=2022-06-29}}</ref><ref name=":1">{{Cite journal |last1=Harris |first1=D. E. |last2=Kapahi |first2=V. K. |last3=Ekers |first3=R. D. |date=February 1980 |title=Westerbork synthesis observations of 8 clusters of galaxies which contain tailed radio galaxies. |url=https://articles.adsabs.harvard.edu/pdf/1980A%26AS...39..215H |journal=Astronomy and Astrophysics, Suppl. Ser. |volume=39 |issue=39 |pages=215–233 |bibcode=1980A&AS...39..215H }}</ref><ref>{{Cite journal |last1=Pizzo |first1=R. F. |last2=Bruyn |first2=A. G. de |date=2009-11-01 |title=Radio spectral study of the cluster of galaxies Abell 2255 |url=https://www.aanda.org/articles/aa/abs/2009/44/aa12465-09/aa12465-09.html |journal=Astronomy & Astrophysics |language=en |volume=507 |issue=2 |pages=639–659 |doi=10.1051/0004-6361/200912465 |arxiv=0909.5198 |bibcode=2009A&A...507..639P |issn=0004-6361}}</ref>
== Description == The Goldfish galaxy is classified as an [[elliptical galaxy]] with an [[active galactic nucleus]] (AGN).<ref name=":0" /> It is a head-tail radio galaxy<ref name=":1" /> or alternatively a [[Fanaroff–Riley classification|Fanaroff-Riley class]] type I narrow-tailed radio galaxy.<ref name=":2">{{Cite journal |last1=Rubeis |first1=E. De |last2=Bondi |first2=M. |last3=Botteon |first3=A. |last4=Weeren |first4=R. J. van |last5=Jong |first5=J. M. G. H. J. de |last6=Rudnick |first6=L. |last7=Brunetti |first7=G. |last8=Rajpurohit |first8=K. |last9=Gheller |first9=C. |last10=Röttgering |first10=H. J. A. |date=2025-07-01 |title=Revealing the intricacies of radio galaxies and filaments in the merging galaxy cluster Abell 2255 - I. Insights from deep LOFAR-VLBI sub-arcsecond resolution images |url=https://www.aanda.org/articles/aa/abs/2025/07/aa55268-25/aa55268-25.html |journal=Astronomy & Astrophysics |language=en |volume=699 |pages=A229 |doi=10.1051/0004-6361/202555268 |arxiv=2505.13595 |bibcode=2025A&A...699A.229D |issn=0004-6361}}</ref><ref name=":3">{{Citation |last1=Gregory |first1=Beatrice Terni de |title=Narrow head-tail radio galaxies at very high resolution |date=2017-11-07 |arxiv=1709.00223 |last2=Feretti |first2=Luigina |last3=Giovannini |first3=Gabriele |last4=Govoni |first4=Federica |last5=Murgia |first5=Matteo |last6=Perley |first6=Rick A. |last7=Vacca |first7=Valentina |journal=Astronomy & Astrophysics |volume=608 |pages=A58 |doi=10.1051/0004-6361/201730878 |bibcode=2017A&A...608A..58T }}</ref> When observed, it is found to have a weak tail feature. The head feature on the other hand, is shown little [[Polarization (cosmology)|polarized]] by around 4%.<ref name=":1" />
Radio imaging made at 1.4 [[Hertz|GHz]] [[Frequency|frequencies]] has found the head of the Goldfish galaxy as clearly resolved with two [[Astrophysical jet|radio jets]] on opposite sides, one of them displaying a bend degree towards the east. A compact [[radio]] core is detected at 5 GHz frequencies. When imaged at 15 GHz, the nucleus and only the part of the northern jet is found.<ref name=":3" /> The tail feature of the Goldfish galaxy is shown to have an total extension of 261 [[Parsec|kiloparsecs]] and further extended by around 180 kiloparsecs towards the direction of southeast.<ref>{{Cite journal |last1=Pizzo |first1=R. F. |last2=Bruyn |first2=A. G. de |last3=Bernardi |first3=G. |last4=Brentjens |first4=M. A. |date=2011-01-01 |title=Deep multi-frequency rotation measure tomography of the galaxy cluster A2255 |url=https://www.aanda.org/articles/aa/pdf/2011/01/aa14158-10.pdf |journal=Astronomy & Astrophysics |language=en |volume=525 |pages=A104 |doi=10.1051/0004-6361/201014158 |arxiv=1008.3530 |bibcode=2011A&A...525A.104P |issn=0004-6361}}</ref> Earlier observations depicted the nucleus as unresolved.<ref>{{Cite journal |last1=L. |first1=Feretti |last2=H. |first2=Boehringer |last3=G. |first3=Giovannini |last4=D. |first4=Neumann |date=January 1997 |title=The radio and X-ray properties of Abell 2255. |journal=Astronomy and Astrophysics |language=en |volume=317 |page=432 |arxiv=astro-ph/9607027 |bibcode=1997A&A...317..432F |issn=0004-6361 }}</ref>
Further observations at sub-arcsecond resolutions have detected traces of [[Radio wave|radio emission]] emitting out from the tail region of the Goldfish galaxy. Evidence also found the tail exhibits a [[Helix|helical]] morphology with jets appearing to spiral around each other before merging back into a single tail feature. A region of increased [[surface brightness]] is detected about 170 kiloparsecs away from the core region.<ref name=":2" />
== References == <references />
== External links == {{WikiSky}} *[https://simbad.u-strasbg.fr/simbad/sim-id?Ident=2MASX%20J17130384%2B6407014&NbIdent=1 Goldfish galaxy on SIMBAD]
{{Draco (constellation)}} [[Category:Radio galaxies]] [[Category:Draco (constellation)]] [[Category:Active galaxies]] [[Category:Elliptical galaxies]] [[Category:SDSS objects]] [[Category:Principal Galaxies Catalogue objects|59858]] [[Category:Astronomical objects discovered in 1974]]