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The viscous decretion disk (VDD) model is able to explain most of thecurrently observable properties of the circumstellar disks of Be stars.However, more stringent tests, focusing on reproducing multitechniqueobservations of individual targets via physical modeling, are needed to studythe predictions of the VDD model under specific circumstances. In the case ofnearby, bright Be star $\beta$ CMi, these circumstances are a very stablelow-density disk and a late-type (B8Ve) central star. The aim is to test theVDD model thoroughly, exploiting the full diagnostic potential of individualtypes of observations, in particular, to constrain the poorly known structureof the outer disk if possible, and to test truncation effects caused by apossible binary companion using radio observations. We use the Monte Carloradiative transfer code HDUST to produce model observables, which we comparewith a very large set of multitechnique and multiwavelength observations thatinclude ultraviolet and optical spectra, photometry covering the intervalbetween optical and radio wavelengths, optical polarimetry, and optical andnear-IR (spectro)interferometry. Due to the absence of large scale variability,data from different epochs can be combined into a single dataset. A parametricVDD model with radial density exponent of $n$ = 3.5, which is the canonicalvalue for isothermal flaring disks, is found to explain observables typicallyformed in the inner disk, while observables originating in the more extendedparts favor a shallower, $n$ = 3.0, density falloff. Modeling of radioobservations allowed for the first determination of the physical extent of a Bedisk (35$^{+10}_{-5}$ stellar radii), which might be caused by a binarycompanion. Finally, polarization data allowed for an indirect measurement ofthe rotation rate of the star, which was found to be $W \gtrsim 0.98$, i.e.,very close to critical.

Multitechnique testing of the viscous decretion disk model I. The stable and tenuous disk of the late-type Be star $\beta$ CMi