Lindblad resonance

Lindblad resonance A resonance that can affect stars in a galaxy's disk at certain distances from the galaxy's centre. It occurs when the natural frequency of the radial (i.e. in and out in the direction of the centre) component of motion of a star in its orbit is the same as the frequency of passage of the star through the maxima of the gravitational potential associated with the spiral pattern. If the star is moving around the centre faster than, and overtakes, the spiral pattern, then an inner Lindblad resonance occurs; if the pattern is moving faster than the star around the centre, then an outer Lindblad resonance occurs. At an inner resonance, energy is fed into the orbits of the stars from the spiral pattern, and vice versa at an outer resonance. The effect is named after B.Lindblad.