The infrared properties of barium stars

The infrared properties of barium stars are studied using published data in the K band and from IRAS . At 12 and 25 μm the emission from barium stars shows no excess over photospheric emission. Thus the claim made by Hakkila that some barium stars show evidence of the presence of warm (～300  K ) circumstellar material is not supported. The 60-μm properties of barium stars are studied using survival analysis methods, and it is found that very few (3.7 ± 2.6 per cent) barium stars exhibit far-infrared excesses. Furthermore, it is found that the incidence of excess emission at 60 μm is lower in barium stars than for normal G and K giants. This may indicate that the mass-transfer event that is assumed to have taken place in barium stars has removed any cool circumstellar material that may have existed in these systems. Alternatively, it is suggested that the incidence of infrared excesses in normal G and K giants may have been over-estimated as a result of not fully accounting for foreground contamination by interstellar cirrus.