HD 209458
star in the constellation Pegasus
HD 209458 is a star with an orbiting exoplanet in the constellation Pegasus. It has an apparent visual magnitude of 7.65 and an absolute magnitude of 4.28. Because it is located at a distance of 157 light-years (48 parsecs) from the Sun as measured via parallax, it is not visible to the unaided eye. With good binoculars or a small telescope it should be easily detectable. The system is drifting closer with a heliocentric radial velocity of −14.8 km/s.
Stellar properties
The spectrum of HD 209458 presents as a late F- or early G-type main-sequence star with a stellar classification of F9 V or G0 V, respectively. It is roughly 3.5 billion years old and is spinning with a projected rotational velocity of 4.2 km/s. The star displays a moderate amount of magnetic activity in its chromosphere. It has a 15% greater mass than the Sun and a 20% larger radius. The abundance of iron, a measure of the metallicity of the star, is solar.
This brief starts where responsible research should: with the source description of “HD 209458” as star in the constellation Pegasus. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the general reference register because the source frames it as star in the constellation Pegasus. Its deeper value depends on whether names, dates, institutions and citations support that framing.
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 Sep 12, 2026. The linked authority identifier is Q186053. None of the 0 selected statements returned an explicit reference.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
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This entry incorporates text from “HD 209458” 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.