[1] Most of the exoplanets currently known were discovered using indirect techniques — such as radial velocity variations of the host star, or the dip in brightness of the star caused by a transiting exoplanet. (sciencedaily.com)
The primary shows long - period radial velocity variations that indicate the presence of a low mass companion whose projected mass is in the planetary regime (m sin i = 9.33 Mjup). (arxiv.org)
This so - called radial velocity variation is what astronomers often measure to find exoplanets. (scientificamerican.com)