HD 90089 (HR 4084; Gliese 392.1) is a star system located in the northerncircumpolar constellationCamelopardalis. With a combinedapparent magnitude of 5.25,[3] it is faintly visible to thenaked eye under ideal conditions. This star is located relatively close at a distance of 75light years,[9] but is drifting away at a rate of almost 8 km/s.[7]
This is anastrometric binary system, initially indicated throughGaia astrometry, and validated in 2026 with the direct detection of the secondary component. The observed separation was of 0.024" along aposition angle of 182.4°.[10] The main component of HD 90089 is an F4main-sequence star with thecalcium K-line and metallic lines of an F2 star.[5] Although the spectral type is of a form that would indicate anAm star, it is not listed in any of the major catalogues ofchemically peculiar stars.[11] The secondary is only 0.45 magnitudes fainter than the primary.[10]
Aninfrared excess has been detected around this system, most likely indicating the presence of acircumstellar disk at a radius of 145 AU. The temperature of this dust is 30 K.[3]
In addition to the inner pair, there is an M0 companion separated 13" away[12] and at approximately the same distance.[13]
^abJohnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars".Communications of the Lunar and Planetary Laboratory.4:99–110.Bibcode:1966CoLPL...4...99J.
^abHartman, Zachary D.; Clark, Catherine A.; Lund, Michael B.; Lester, Kathryn V.; Caballero, José A.; Howell, Steve B.; Ciardi, David; Deveny, Sarah; Everett, Mark E. (2026-01-08). "Paving the Road to the Habitable Worlds Observatory with High-Resolution Imaging I: New and Archival Speckle Observations of Potential HWO Target Stars".The Astrophysical Journal.arXiv:2601.05387.
