HD 16760
HD 16760 is a binary star system approximately 186 light-years away in the constellation Perseus. The primary star HD 16760A is a G-type main sequence star similar to the Sun. The secondary, HD 16760B is 1.521 magnitudes fainter and located at a separation of 14.6 arcseconds from the primary, corresponding to a physical separation of at least 660 AU.
The primary star also has a companion, either a red dwarf or a brown dwarf, that is designated HD 16760 b. SIMBAD also lists the designation HD 16760C for this object.
Companion (HD 16760 b)
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Hierarchy of orbits in the HD 16760 system
Hierarchy of orbits in the HD 16760 system
The companion object was discovered independently by the SOPHIE extrasolar planets program and the N2K Consortium. It has a minimum mass slightly exceeding the lower limit required for fusion of deuterium in its interior. This criterion is sometimes used to distinguish between brown dwarfs, which lie above the limit, and planets which lie below the limit. However its orbit is nearly circular, indicating that it may have formed in the same way as planets do, from a circumstellar disc. The formation of massive planets up to 20–25 Jupiter masses has been predicted in some models of the core accretion process. The identity of this object as a brown dwarf or a massive planet was thus unclear.
However, data analysed from direct imaging of the companion object using ground-based telescopes fitted with adaptive optics has revealed that it is aligned in a much more face-on orbit than previously realised. Consequently, its mass has been revised upwards. With a mass calculated at around one quarter that of the Sun, or nearly 300 Jupiter masses, it easily qualifies as a stellar object, probably a red dwarf. A 2020 study using Gaia astrometry supported a stellar true mass, but a 2026 study instead found a mass consistent with a brown dwarf. These two studies do not incorporate data from direct imaging.
The same 2026 study found evidence for a second companion from radial velocity. This candidate object would have a 234-day period and a minimum mass of 0.4 Jupiter masses, making it a probable planet.