Astrometric monitoring of the Sirius binary system over the past century has yielded several predictions for an unseen third system component, the most recent one suggesting a ≲50 MJup object in a ∼6.3 year orbit around Sirius A. Here we present two epochs of high-contrast imaging observations performed with Subaru IRCS and AO188 in the 4.05 μm narrowband Br α filter. These data surpass previous observations by an order of magnitude in detectable companion mass, allowing us to probe the relevant separation range down to the planetary-mass regime (6-12 MJup at 1″, 2-4 MJup at 2″, and 1.6 MJup beyond 4″). We complement these data with one epoch of M-band observations from MMT/AO Clio, which reach comparable performance. No data set reveals any companion candidates above the 5σ level, allowing us to refute the existence of Sirius C as suggested by the previous astrometric analysis. Furthermore, our Br α photometry of Sirius B confirms the lack of an infrared excess beyond the white dwarf's blackbody spectrum.
- planetary systems
- stars: individual (Sirius A, Sirius B)
- techniques: high angular resolution
- white dwarfs
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science