XO-2
star system in the constellation Lynx
XO-2 is a binary star system about 490 light-years (150 parsecs) away in the constellation Lynx. It consists of two components, XO-2N and XO-2S, both of which host planetary systems.
Star system
This system is unusual in that the stars are not typically referred to as components A & B, but are designated based on their positions in the sky: XO-2N is the northern star and XO-2S is the southern star.
Both of the stars are slightly cooler than the Sun and are nearly identical to each other. The system has a magnitude of 11 and cannot be seen with the naked eye but is visible through a small telescope. These stars are also notable for their large proper motions.
XO-2N and XO-2S have a separation of approximately 4,600 AU.
Planetary systems
Two planets were reported to orbit around XO-2S in 2014 using the radial velocity method. One of them is Jupiter-mass and another has a mass comparable to Saturn. A 2024 study found evidence for a third, super-Jupiter mass planet around XO-2S.
There is one confirmed exoplanet orbiting XO-2N. XO-2Nb, which is classified as a hot Jupiter, was discovered by the XO Telescope using the transit method around XO-2N in 2007. It was initially the only known planet in the system and was referred to as XO-2b.
This brief starts where responsible research should: with the source description of “XO-2” as star system in the constellation Lynx. 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 May 13, 2026. The linked authority identifier is Q113630358. None of the 0 selected statements returned an explicit reference. The first chronological checks are 2014, 2024 and 2007.
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This entry incorporates text from “XO-2” 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.