UDFy-38135539 (also known as "HUDF.YD3") is the Hubble Ultra Deep Field (UDF) identifier for a galaxy which was calculated as of October 2010 to have a light travel time of 13.1 billion years with a present proper distance of around 30 billion light-years. It was discovered by three teams in September 2009 in sensitive infrared Hubble Space Telescope images and identified by these as source UDF-38135539 (R Bouwens et al.), source HUDF.YD3 (A Bunker et al.) and source 1721 (R McLure et al.), and additionally reported in the Astrophysical Journal, and the Monthly Notices of the Royal Astronomical Society. All teams independently identified the source to likely be an extremely distant galaxy because there was no measurable light at visible wavelengths (caused by absorption of hydrogen gas along the line of sight). Following the discovery of this candidate distant galaxy, another team targeted this object with ground-based spectroscopy to confirm the distance, reporting a redshift z=8.6. However, attempts to replicate this observation strongly suggest the original claim was in error, meaning that at the present time the galaxy only has a photometric redshift estimate.
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This article is an automated import of the Wikipedia article "UDFy-38135539", available at https://en.wikipedia.org/wiki/UDFy-38135539 . Text is licensed under CC BY-SA 4.0.