Differential Multi-Star Decorrelation for Exoplanet Detection in Triple Systems: The Challenging Case of Polaris
Authors/Creators
Description
Submitted to Astronomische Nachrichten, 19 March 2026
We introduce Differential Multi-Star Decorrelation (DMSD), a technique that uses quasi-simultaneous spectroscopy of a resolved stellar companion as a common-mode calibrator to suppress long-timescale instrumental systematics in radial-velocity exoplanet searches. When two gravitationally bound stars are observed through the same spectrograph within a short time window, instrumental drifts, calibration aging, and barycentric correction errors imprint correlated signatures on both. Regressing the host-star radial velocity against the companion's spectral diagnostics removes the shared component while preserving the planetary signal.
We derive an analytic suppression factor η ≈ 1/√(1 − ρ²), where ρ is the common-mode correlation coefficient, and validate it with an end-to-end simulation. Applied to the Polaris triple system, DMSD reduces alias power at the habitable-zone period (P ≈ 2 yr) by a factor of ~4 and the false-positive rate from 12% to <1%. A 5 M⊕ planet at 1.97 AU around Polaris B would be detectable at SNR ≈ 3 in ~5 yr with HARPS-N at TNG.
The method is applicable to any resolved multiple-star system and represents a new application of differential measurement to the radial-velocity method. An interactive browser-based simulation is included as supplementary material.
Submitted to Astronomische Nachrichten, 19 March 2026.
Keywords
exoplanets; radial velocity; binary stars; triple stars; Polaris; instrumental systematics; differential spectroscopy
License
CC-BY-4.0
Related identifiers
- Interactive simulation: https://boriskriger.github.io/publicationsiiir/dmsd_simulation.html (isSupplementedBy, URL)
Files to upload
- DMSD_AN_v2.pdf — manuscript
- DMSD_AN_v2.tex — LaTeX source
- dmsd_simulation.html — interactive simulation (supplementary)
Authors
Kriger, Boris (ORCID: 0009-0001-0034-2903)
Affiliation
Department of Theoretical Astrophysics and Cosmology, Information Physics Institute (ROR: 05y04vm71)