Finding ExoplanetsAnother signature of an exoplanet would be doppler shifts in the star's spectral lines as they orbit their common center of mass. The doppler shift technique(also sometimes called the radial velocity technique) has been the easiest and most prolific way to find exoplanets so far. At of the time of writing over 500 exoplanets have been found using the doppler shift technique.The searches have so far focussed on stars similar to the Sun, though two systems have planets orbiting a pulsar (a type of ultra-compact, dead star discussed in the stellar evolution chapter---planets found using a variation of the doppler shift technique called the timing technique), ten systems have M-type red dwarf stars(including one that has a terrestrial-sized planet in its habitable zone), four systems have brown dwarfs, four systems have A-type stars, and three have B-type stars. Like the astrometric technique,the doppler shift techniqueis well-suited to finding massive jovian planets close to their parent stars. The number of systems discovered and the
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