Anomalous dust in the environment of Herbig Ae/Be stars

Photometric data in the UBVRI bands of Herbig Ae/Be stars has been analysed to study the wavelength dependence of extinction to these objects. The colour excess ratios E(U−B)/E(B−V), E(V−R)/E(B−V), E(V−I)/E(B−V) and E(V−I)/E(V−R) for these stars have been computed and compared with those for the mean interstellar extinction. The colour excess ratios for Herbig Ae/Be stars are found to be anomalous. For a majority of the Herbig Ae/Be stars the values of the colour excess ratios imply that the dust causing extinction to these stars is dominated by grains that are larger in size than the average dust grain in the interstellar medium