Gamma Cephei Ab
extrasolar planet in the constellation Cepheus
Gamma Cephei Ab (abbreviated γ Cephei Ab, γ Cep Ab), formally named Tadmor , is an exoplanet approximately 45 light-years away in the constellation of Cepheus that orbits Gamma Cephei A. The planet was suspected to exist in 1988, and later confirmed in 2003, technically making it the first exoplanet discovered.
Naming
In July 2014 the International Astronomical Union (IAU) launched NameExoWorlds, a process for giving proper names to certain exoplanets. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name for this planet was Tadmor. It was submitted by the Syrian Astronomical Association and is the ancient Semitic name and modern Arabic name for the city of Palmyra, a (UNESCO) World Heritage Site.
Detection and discovery
1988 claims
The first indications of γ Cephei Ab were reported in July 1988. The planet was tentatively identified by a Canadian team of astronomers, which was led by Bruce Campbell, Gordon Walker and Stephenson Yang, while its existence was also announced by Anthony Lawton and P. Wright in 1989. Though not confirmed, this would have been the first true discovery of an extrasolar planet, and it was hypothesized based on the same radial velocity technique later used successfully by others. However, the claim was retracted in 1992 due to the quality of the data not being good enough to make a solid discovery.
2003 confirmation
On 7 May 2003, γ Cephei Ab was finally confirmed.
This brief starts where responsible research should: with the source description of “Gamma Cephei Ab” as extrasolar planet in the constellation Cepheus. Everything that follows is an evidence route, not borrowed authority.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 23, 2026. The linked authority identifier is Q429779. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1988, 2003, 2014 and 2015.
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This entry incorporates text from “Gamma Cephei Ab” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.