天苑四
The magnetic field on the surface of Epsilon Eridani causes variations in the hydrodynamic behaviour of the photosphere. This results in greater jitter during measurements of its radial velocity. Variations of −1 were measured over a 20 year period, which is much higher than the measurement uncertainty of −1. This makes interpretation of periodicities in the radial velocity of Epsilon Eridani, such as those caused by an orbiting planet, more difficult.