The next seven brightest stars in Cassiopeia are also all confirmed or suspected variable stars, including 50 Cassiopeiae which was not given a Greek letter by Bayer and is a suspected variable with a very small amplitude. Zeta Cassiopeiae is a suspected slowly pulsating B-type star . Eta Cassiopeiae is a spectroscopic binary star with a period of 480 years, and a suspected RS Canum Venaticorum variable . The primary is a yellow-hued star of magnitude and the secondary is a red-hued star of magnitude . The system is 19 light-years from Earth. Kappa Cassiopeiae is a blue supergiant of spectral type that is some 302,000 times as luminous as the Sun and has 33 times its diameter.  It is a runaway star , moving at around million mph relative to its neighbors (1,100 kilometers per second).  Its magnetic field and wind of particles creates a visible bow shock 4 light-years ahead of it, colliding with the diffuse, and usually invisible, interstellar gas and dust. The dimensions of the bow shock are vast: around 12 light-years long and light-years wide.  Theta Cassiopeiae , named Marfak, is a suspected variable star whose brightness changes by less than a tenth of a magnitude. Iota Cassiopeiae is a triple star 142 light-years from Earth. The primary is a white-hued star of magnitude and an α 2 Canum Venaticorum variable , the secondary is a yellow-hued star of magnitude , and the tertiary is a star of magnitude . The primary and secondary are close together but the primary and tertiary are widely separated. Omicron Cassiopeiae is a triple star and the primary is another γ Cassiopeiae variable.