Stellar engines are a conceptual class of observatories that use a star's emission to generate useful energy. Cathcart and Badescu were the first to propose the idea. Some variations have been using this power to generate momentum, accelerating a star and anything orbiting it in a specific direction. The design of such a structure will result in the architects being classified as a Type-II community on the Kardashev level.
There are three classes of stellar engines which was defined as:
Class A which is named as Shkadov thurster: The Shkadov thruster (decided to title after Dr. Leonid Shkadov, who had first suggested it or a Category A stellar engine is among the most understanding of the concept of a stellar engine. A stellar fusion reactor would comprise of a huge rear-view glide a substantial form of solar statite broad enough to have been classified as a megastructure—that would regulate gravitational effect towards each other and radioactive pressure away from the star. That's because the star's heat generated pressure is now uneven, meaning that more energy is released in one path than another, the 'surplus' heat generated pressure serves as net thrust, boosting the star in the path of the floating steatite. Although such thrust and momentum would be negligible, such a device could be sustainable for centuries. Any celestial system connected to the star will be 'pulled' along by it. The cumulative thrust generated by representing half of the solar production will be 1.28 1018 N for a star like the Sun, which has a brightness of 3.85 1026 W and a density of 1.99 1030 kg. After just one million of years, this will result in a conferred rate of 200 m/s and a deviation of 0.03 light-years from either the original position. After hundred million years, the pace will be 20 km/s and the distance 34,000 light-years, a little more than a quarter of the Andromeda galaxy's projected width.
A Class B stellar engine is a Fusion reactor constructed around for a star that utilizes the temperature gradient between both the interstellar and the star space to obtain accessible energy to the system, likely using photovoltaic cells and heating engines. Such a device, except for the Shkadov thruster, is not propellant.
A Class C stellar engine, including the Badescu-Cathcart engine, blends the two different classes, utilizing both the traction features of the Shkadov propeller and the power generating attributes of a Class B engine.