IRAS Observations of Symbiotic Stars

Abstract

AbstractOf the 129 symbiotic stars in Allen's (1984) catalogue, 42 were found to be IRAS sources. Of these 42 IRAS sources, 22 are D-type (symbiotic Miras), 5 are D'-type (yellow symbiotics) and 15 are S-type. The separation of S, D and D’ types into three distinct groups is clearer in the log[fλ(25μm)/fλ(12μm)] versus (H-K) diagram. The IRAS fluxes of S-type symbiotics are consistent with that observed from normal M giants. This result suggests that mass-loss rate from most of the S-type symbiotics is similar to that from normal M giants. The IRAS data of D-type symbiotics shows evidence for the presence of dust envelopes. The masses of the dust envelopes (10-6 to 10-7 Mo) around Miras in D-type symbiotics are similar to that observed in field Mira variables. These results suggest that mass-loss rates in symbiotic Miras are similar to those from field Mira variables and also that the mass loss from symbiotic Miras is pulsationally driven similar to that found in field Mira variables by Whitelock, Pottasch and Feast (1987). Analysis of IRAS data of yellow symbiotics Ml-2, AS201, Cnl-1, Wray 157. and HD149427 suggests that they are young planetary nebulae containing a binary nucleus. Ml-2, AS201 and Cnl-1 show evidence for the presence of evolved hot companions. The evolutionary stage of the late type (F-G) companions is not clear.