40 Aurigae

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40 Aurigae is a binary star system in the northern constellation Auriga. It shines with an apparent magnitude of about 5.35, so it is just barely visible to the naked eye under good conditions. The system is about 340 light-years away. It is a double-lined spectroscopic binary, meaning the two stars are very close together and we detect their motion from shifts in the spectrum rather than by resolving them with a telescope. The stars orbit each other every 28.28 days in an elongated path (eccentricity about 0.56). The brighter star is an A-type main-sequence star with a peculiar Am spectrum, and its temperature is around 7,840 K. It also has a higher metal content than the Sun.