DMPP-4: Candidate sub-Neptune mass planets orbiting a naked-eye star

Abstract We present radial velocity measurements of the very bright (V ∼ 5.7) nearby F star, DMPP-4 (HD 184960). The anomalously low Ca ii H&K emission suggests mass loss from planets orbiting a activity host star. Periodic variability with ∼10 m s−1 amplitude is found to persist over >4 year timescale. Although non-simultaneous photometric in four tess sectors supports view an inactive we identify periodic signals and also find spectroscopic evidence for stellar activity. used posterior sampling algorithm that includes number Keplerian signals, Np, as free parameter test compare (1) purely models (2) model linear correlation (3) Gaussian processes. A preferred model, one quasi-periodic process indicates planet period $P_\textrm {b} = 3.4982^{+0.0015}_{-0.0027}$ d corresponding minimum $m_\textrm {b}\, \textrm {sin}\, i 12.2^{+1.8}_{-1.9}$ M⊕. Without further high time resolution observations longer timescale, cannot definitively rule out 2 candidates 2.4570^{+0.0026}_{-0.0462}$ d, 8.0^{+1.1}_{-1.5}$ M⊕ {c} 5.4196^{+0.6766}_{-0.0030}$ 12.2^{+1.4}_{-1.6}$ candidate lie region below lower-envelope Neptune Desert. Continued may originate highly irradiated or yet undetected body system.