Piercing the Glare: Direct Imaging Search for Planets in the Sirius System

Abstract

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 \leq50 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 \mum narrow-band Br alpha 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 M_Jup at 1", 2-4 M_Jup at 2", and 1.6 M_Jup beyond 4"). We complement these data with one epoch of M-band observations from MMT/AO Clio, which reach comparable performance. No dataset reveals any companion candidates above the 5-sigma level, allowing us to refute the existence of Sirius C as suggested by the previous astrometric analysis. Furthermore, our Br alpha photometry of Sirius B confirms the lack of an infrared excess beyond the white dwarf's blackbody spectrum.

6 pages, 5 figures, accepted for publication in ApJ Letters

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• SPOTS: The Search for Planets Orbiting Two Stars. III. Complete Sample and Statistical Analysis
• A New Method for Finding Nearby White Dwarf Exoplanets and Detecting Biosignatures
• High contrast imaging at 10 microns, a search for exoplanets around: Eps Indi A, Eps Eri, Tau Ceti, Sirius A and Sirius B
• Impact of planetesimal eccentricities and material strength on the appearance of eccentric debris disks
• Combining high contrast imaging and radial velocities to constrain the planetary architecture of nearby stars
• Improved companion mass limits for Sirius A with thermal infrared coronagraphy using a vector-apodizing phase plate and time-domain starlight-subtraction techniques
• High contrast imaging with Fizeau interferometry: The case of Altair
• An Imaging Search for Post-Main-Sequence Planets of Sirius B
• Galactic astronomy with AO: Nearby star clusters and moving groups