Context. Simulations suggest that gas heating due to radiative feedback is a key factor in whether or not multiple protostellar systems will form. Chemistry is a good tracer of the physical structure of a protostellar system, since it depends on the temperature structure.
Aims: We aim to study the relationship between envelope gas temperature and protostellar multiplicity.
Methods: Single dish observations of various molecules that trace the cold, warm, and UV- irradiated gas were used to probe the temperature structure of multiple and single protostellar systems on 7000 AU scales.
Results: Single, close binary, and wide multiples present similar current envelope gas temperatures, as estimated from H
2CO and DCO
+ line ratios. The temperature of the outflow cavity, traced by c-C
3H
2, on the other hand, shows a relation with bolometric luminosity and an anticorrelation with envelope mass. Although the envelope gas temperatures are similar for all objects surveyed, wide multiples tend to exhibit a more massive reservoir of cold gas compared to close binary and single protostars.
Conclusions: Although the sample of protostellar systems is small, the results suggest that gas temperature may not have a strong impact on fragmentation. We propose that mass, and density, may instead be key factors in fragmentation. The reduced spectra are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/620/A30">http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/620/A30</A>
