Coralie radial velocities for l Car

Two successive maxima yield {Delta}_max_{Theta}=13.1+/-0.7(stat.){mu}as for uniform disc models and 22.5+/-1.4(stat.){mu}as (4 percent of the total angular variation) for limb-darkened models. By comparing new RVs with 2014 RVs, we show modulation to vary in strength. Barring confirmation, our results suggest the optical continuum (traced by interferometry) to be differently affected by modulation than gas motions (traced by spectroscopy).

This implies a previously unknown time dependence of projection factors, which can vary by 5 percent between consecutive cycles of expansion and contraction. Additional interferometric data are required to confirm modulated angular diameter variations. By understanding the origin of modulated variability and monitoring its long-term behaviour, we aim to improve the accuracy of BW distances and further the understanding of stellar pulsations.