The star sign * is an indication that the displayed temperature precision may not be within the specification of the camera. This could happen when the camera is warming up after a cold start or you have changed the temperature range setting and in other cases where the firmware in the camera detects "rapidly" changing internal temperatures or other parameters. If the object temperature is within the actual temperature setting, this sign will disappear after a shutter movement or NUC.

The bigger than sign > indicates a total out of range and the temperature reading is no longer valid. This indication usually comes up when the object temperature is 5-10% higher than the maximum temperature of the actual range. The camera detector could be in saturation and the same temperature is shown all the time.