We have used the Keck I telescope to resolve at mid-infrared wavelengths the dust emission from HD 56126 ( IRAS 07134+1005 ) , a post-Asymptotic Giant Branch carbon star with a detached dust shell .
The gross morphology of the image can be explained by a strong wind which started to die about 1500 years ago .
If the star had an effective temperature , T _ { * } , near 2600 K when it was losing { \sim } 3 { \times } 10 ^ { -5 } M _ { \odot } yr ^ { -1 } , then during the past 1500 yr , the average value of dT _ { * } / dt has been +2.2 K yr ^ { -1 } .
With such a time variation of the effective temperature , the 11.7 { \mu } m image can be approximately reproduced if the mass loss rate varied as T _ { * } ^ { -8.26 } , as proposed in recent models for dust-driven winds .
Since the mass loss rate appears to be very sensitive to the effective temperature of the star , we speculate that the observed deviations from spherical symmetry of the dust shell can be explained by plausible variations in the surface temperature of the mass-losing star caused by rotation and/or magnetic fields .