A1703 zD6
{{Notability|Astro|date=August 2019}}
{{Infobox galaxy
| name = A1703 zD6
| image = 250px
| caption = A1703 zD6 (top right)
| alt =
| epoch = J2000
| constellation name = Canes Venatici
| h_radial_v = {{convert|2112038|km/s|abbr=on}}
| gal_v = {{convert|2112133|km/s|abbr=on}}
| dist_ly = {{convert|12.9|e9ly|e9pc|abbr=unit|lk=on}} (light travel distance)
{{convert|29|e9ly|e9pc|abbr=unit|lk=on}}
(comoving distance)
| appmag_v = 25.8J
| names = [BBZ2012] A1703-zD6
}}
A1703 zD6 is a strongly lensed Lyman-alpha emitter. It is located behind a foreground galaxy cluster known as Abell 1703, hence its name. It has a spectroscopically determined redshift of over 7, corresponding to a light travel time of 12.9 billion years.{{citation needed|date=August 2019}} It is located in the Canes Venatici constellation. It was discovered in 2012, by a group led by L. D. Bradley, published in The Astrophysical Journal.{{cite journal|bibcode=2012ApJ...747....3B|doi=10.1088/0004-637X/747/1/3|title= Through the looking glass: bright, highly magnified galaxy candidates at z ~ 7 behind A1703|journal=The Astrophysical Journal|volume=747|issue=1|pages=3|year=2012|last1=Bradley|first1=L. D.|last2=Bouwens|first2=R. J.|last3=Zitrin|first3=A.|last4=Smit|first4=R.|last5=Coe|first5=D.|last6=Ford|first6=H. C.|last7=Zheng|first7=W.|last8=Illingworth|first8=G. D.|last9=Benítez|first9=N.|last10=Broadhurst|first10=T. J.|arxiv=1104.2035|s2cid=118567077 }}
The C IV emission line (with a wavelength of 1548 Å) was detected from this galaxy, signifying triply ionized carbon. Because it takes high amounts of energy to triply ionize carbon, it may suggest that A1703 zD6 has an active galactic nucleus (AGN), or a population of very young, hot, and metal-poor stars.{{cite journal|bibcode=2015MNRAS.454.1393S|title=Spectroscopic detection of C IV λ1548 in a galaxy at z = 7.045: Implications for the ionizing spectra of reionization-era galaxies|journal=Monthly Notices of the Royal Astronomical Society|volume=454|issue=2|pages=1393|last1=Stark|first1=Daniel P.|last2=Walth|first2=Gregory|last3=Charlot|first3=Stéphane|last4=Clément|first4=Benjamin|last5=Feltre|first5=Anna|last6=Gutkin|first6=Julia|last7=Richard|first7=Johan|last8=Mainali|first8=Ramesh|last9=Robertson|first9=Brant|last10=Siana|first10=Brian|last11=Tang|first11=Mengtao|last12=Schenker|first12=Matthew|year=2015|arxiv=1504.06881|doi=10.1093/mnras/stv1907| doi-access=free }} Subsequent investigations found that the ionization source is likely to be the latter: a cluster of stars (abbreviated SF, for star-forming region).{{cite journal|doi=10.1093/mnras/sty1658|title=Nature and chemical abundances of a sample of Lyman-α emitter objects at high redshift|journal=Monthly Notices of the Royal Astronomical Society|volume=479|issue=2|pages=2294–2307|year=2018|last1=Dors|first1=O. L.|last2=Agarwal|first2=B.|last3=Hägele|first3=G. F.|last4=Cardaci|first4=M. V.|last5=Rydberg|first5=Claes-Erik|last6=Riffel|first6=R. A.|last7=Oliveira|first7=A. S.|last8=Krabbe|first8=A. C.|doi-access=free |bibcode=2018MNRAS.479.2294D|arxiv=1806.07732}}