Differential Multi-Star Decorrelation (DMSD)

Interactive simulation companion to: Kriger, B. (2026). Submitted to Astronomische Nachrichten, 19 March 2026.

The host star B contains a planetary RV signal, stellar jitter, and instrumental systematics. The reference star A shares the same systematics (scaled by ρ) but has no planet. Regressing B against A removes the common-mode component.

RṼ_B(t) = RV_B(t) − β · RV_A(t) | η ≈ 1/√(1 − ρ²)

Planet semi-amplitude K

0.47 m/s

Stellar jitter (host B)

1.5 m/s

Systematic amplitude

0.30 m/s

Common-mode fraction ρ

0.85

Raw RV of host star B

Reference star A

DMSD-corrected RV of B

Lomb–Scargle periodogram

Dashed red: raw. Solid green: DMSD-corrected. Vertical line: true planet period (P = 2.1 yr).

How it works

In a resolved triple system like Polaris, stars A and B are observed on the same spectrograph within minutes. Instrumental drifts, calibration lamp aging, and focus changes affect both stars similarly. These common-mode systematics create false periodogram peaks at ~1 yr. DMSD removes them by OLS regression of RV_B against RV_A.

Try ρ = 0 (no improvement) vs ρ = 0.95 (strong suppression). Increase systematic amplitude to see alias peaks.