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The group of lambda Bootis type stars comprises late B- to early F-type,Population I objects which are basically metal weak, in particular the Fe groupelements, but with the clear exception of C, N, O and S. One of the theories toexplain the abundance pattern of these stars involves circumstellar orinterstellar matter around the objects. Hence, we have compiled all availabledata from the literature of well established members of the lambda Bootis groupredward of 7000A in order to find evidence for matter around these objects.Furthermore, we present unpublished ISO as well as submillimeter continuum andCO (2-1) line measurements to complete the data set. In total, measurements for34 (26 with data redward of 20 mu m) well established lambda Bootis stars areavailable. There is evidence for an infrared excesses in six stars (HD 31295,HD 74873, HD 110411, HD 125162, HD 198160/1 and HD 210111) and two are doubtfulcases (HD 11413 and HD 192640) resulting in a percentage of 23% (excluding thetwo doubtful cases). Dust models for these objects show fractional dustluminosities comparable to the Vega-type stars and slightly higher dusttemperatures. ISO-SWS spectroscopy for HD 125162 and HD 192640 resulted in thedetection of pure stellar HI lines ruling out an active accretion disk (asfound for several Herbig Ae/Be stars) around these objects. The submillimetermeasurements gave only upper limits for the line and continuum fluxes.Comment: 16 pages, 5 figures, accepted by A&

A study of λ Bootis type stars in the wavelength region beyond 7000 Å