Linear activity terms weaken the 35-day velocity peak in 232 HD 40307 HARPS nights

We search 30 to 40 days in two reductions of 448 HARPS exposures on 232 nights. Three linear activity terms reduce the largest fitted wave power by 57.2 percent in SERVAL and 54.8 percent in DRS. Conditional scan tail fractions rise to 0.0175 to 0.0900 with 30-day and 90-day residual signs. Neither reduction then passes the stated 1 percent threshold. A fixed 34.62-day wave has amplitudes of 0.052 and 0.140 m/s after activity adjustment. The activity design retains at least 96.3 percent of the squared signal norm for every phase at that fixed period. Specified 1 m/s injections have high conditional recovery. The evidence supports further activity tests but does not prove a stellar cause or exclude a planet. Both reductions use the same exposures. No independent instrument series is fit. Code, aggregate results, source hashes, retrieval steps and a figure are included. External source records stay outside the baseline publication.

astronomy · HD 40307 · HARPS · stellar activity · radial velocity · conditional noise test · injection recovery