The TRENDS High-contrast Imaging Survey. VII. Discovery of a Nearby Sirius-like White Dwarf System (HD 169889)

Monitoring the long-term radial velocity (RV) and acceleration of nearby stars has been proven as an effective method for directly detecting binary and substellar companions. Some fraction of nearby RV trend systems are expected to be comprised of compact objects that likewise induce a systemic Doppler signal. In this paper, we report the discovery of a white dwarf (WD) companion found to orbit the nearby (π = 28.297 0.066 mas) G9 V star HD 169889. High-contrast imaging observations using NIRC2 at the W. M. Keck Observatory and LMIRCam at the Large Binocular Telescope (LBT) Observatory uncover the (ΔH = 9.76 0.16, ΔL′ = 9.60 0.03) companion at an angular separation of 0 8 (28 au). Thirteen years of precise Doppler observations reveal a steep linear acceleration in the RV time series and place a dynamical constraint on the companion mass of M ≥ 0.369 0.010 M . This "Sirius-like" system adds to the census of WD companions suspected to be missing from surveys of in the solar neighborhood.