One of the most recent types added to the list are the howler variety.
Howler stars received their name because of their characteristic radio frequency emission which when received on standard radio-telescope equipment resembles a howling noise similar to wind or the suction sound associated with a whirlpool.
It’s not understood how a cloud star can also be a radio frequency emitter (RFE) because, once again, their low density eliminates the usual sources by which normal stars emit light, heat and all other types of electromagnetic radiation.
One possibility that’s been suggested is that cloud stars that “howl” don’t actually create the radio transmissions themselves like a pulsar does but rather only alter the signal produced by another star just like a pocket of gas can act like a prism when regular light from another source is passed through it.
This is similar to one of the theories used to explain the existence of cloud stars themselves, that being resonances or eddies in the gravitational fields of stars which creates areas of stronger than normal gravity where gas and other matter subsequently collect yet without the presence of any mass which would normally be necessary to create such a gravitational field.
In fact some astronomers at first referred to these cloud star formations as “sargasso” stars in reference to the Sargasso Sea in the Atlantic Ocean, a central area where debris becomes trapped due to the ocean currents which revolve around it and independently of any influence by land.