SDSS J1229+1122
{{Short description|Star in the constellation of Virgo}}
{{sky|12|29|52.66|+|11|22|27.8|55000000}}
{{Starbox begin}}
{{Starbox observe
| constell = Virgo
| epoch = J2000.0{{cite web |url= http://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Obj_id&objid=47435649&objname=9&img_stamp=YES&hconst=73.0&omegam=0.27&omegav=0.73&corr_z=1 |title= INDEX for SDSS J122952.66+112227.8 |publisher= NASA/IPAC Extragalactic Database |access-date= 2014-05-05 }}
}}
{{Starbox character
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{{Starbox astrometry
| dist_ly = 55 million
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{{Starbox catalog
| names = SDSS J122952.66+112227.8
}}
{{Starbox reference
| Simbad = SDSS+J122952.66%2b112227.8
}}
{{Starbox end}}
SDSS J1229+1122 (SDSS J122952.66+112227.8) is a blue supergiant O-type star in the tail of dwarf irregular galaxy IC 3418. It illuminates a nebula clump of gas, and was discovered from the spectrum of the illumination source. The clump of gas resides in a tail caused by ram pressure stripping of gas from the galaxy by the galaxy cluster.{{cite journal |title= Discovery of a Possibly Single Blue Supergiant Star in the Intra-cluster Region of Virgo Cluster of Galaxies |doi= 10.1088/2041-8205/767/2/L29 |bibcode= 2013ApJ...767L..29O |arxiv= 1304.2560 |journal= The Astrophysical Journal Letters |volume= 767 |issue= 2 |id= L29 |page= 6 |date= 9 April 2013 |publication-date= April 2013 |first1= Youichi |last1= Ohyama |first2= Ananda |last2= Hota |s2cid= 119020275 }} It was determined to be a blue supergiant through analysis of its spectrum taken with the 8m Subaru telescope.{{cite web |url= http://www.naoj.org/Pressrelease/2013/04/10/index.html |title= Discovery of a Blue Supergiant Star Born in the Wild |date= 10 April 2013 |publisher= Subaru Telescope }} The discovery was made by Youichi Ohyama and Ananda Hota,{{cite magazine |date=16 April 2013 |title=Researchers Discover Aging Blue Supergiant Star In Virgo Cluster |url=http://www.asianscientist.com/in-the-lab/researchers-discover-aging-blue-supergiant-star-virgo-cluster-2013/ |magazine=Asian Scientist}} using the Subaru Telescope.{{cite news |last=Miller |first=Erin |date=19 April 2013 |title=Island telescopes spot rare blue supergiant star |publisher=West Hawaii Today |url=http://westhawaiitoday.com/sections/news/local-news/island-telescopes-spot-rare-blue-supergiant-star.html}} This discovery was then followed up with the AstroSat to image it with finer angular resolution in the ultraviolet than that of GALEX. With addition of HST optical data the astronomers believe that the ram pressure stripped tail of IC3418 many have many such young star forming clumps and potentially single O-type stars.
Until the discovery of the doubly gravitationally lensed MACS J1149 Lensed Star 1 (also known as Icarus) in 2018, SDSS J1229+1122 was the most distant-known star, at {{convert|55|e6ly|Mpc|lk=on}} (stars more distant than this are only known through events that they cause, such as stellar explosions of supernovae and gamma ray bursts).{{cite news |publisher= Sky and Telescope |url= http://www.skyandtelescope.com/astronomy-news/the-most-distant-star-everseen/ |title= The Most Distant Star Ever Seen? |author= Camille M. Carlisle |date= 12 April 2013 }} (The record for the most distant star is Earendel, as of October 2023.)
The star (SDSS J1229+1122) and its galaxy are in the Virgo Cluster of galaxies. The clump of gas that the star illuminates is referred to as D3 or IC3418 D3, and lies within a filamentary structure referred to as F1 or IC3418 F1. The galactic tail and all within it are escaping the galaxy to become intracluster flotsam, unattached to any galaxy, just the cluster.