This synchronous rotation is considered a defining feature of polars. Additionally, the WD's magnetic field captures the accretion stream from the donor star before it can develop into an accretion disk. The capture of the accretion stream is known as threading, and it occurs when the magnetic pressure from the WD matches the stream's ram pressure.
The synchronized rotation is a defining feature of polars. Furthermore, the WD's magnetic field ensnares the accretion stream from the donor star before it forms an accretion disk. This trapping process is known as threading, and it happens when the WD's magnetic pressure aligns with the ram pressure of the accretion stream.