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We present the results of a survey of young intermediate mass stars (age$<$~5 Myr, 1.5 $<M_{\star} \leq $ 15 $M_{\odot}$) in the W5 massive starforming region. We use combined optical, near-infrared and {\it Spitzer} SpaceTelescope photometry and optical spectroscopy to define a sample of stars ofspectral type A and B and examine their infrared excess properties. We findobjects with infrared excesses characteristic of optically thick disks, i.e.Herbig AeBe stars. These stars are rare: $<$1.5% of the entire spectroscopicsample of A and B stars, and absent among stars more massive than 2.4$M_\odot$. 7.5% of the A and B stars possess infrared excesses in a variety ofmorphologies that suggest their disks are in some transitional phase between aninitial, optically thick accretion state and later evolutionary states. Weidentify four morphological classes based on the wavelength dependence of theobserved excess emission above theoretical photospheric levels: (a) theoptically thick disks; (b) disks with an optically thin excess over thewavelength range 2 to 24 $\micron$, similar to that shown by Classical Bestars; (c) disks that are optically thin in their inner regions based on theirinfrared excess at 2-8 $\micron$ and optically thick in their outer regionsbased on the magnitude of the observed excess emission at 24 $\micron$; (d)disks that exhibit empty inner regions (no excess emission at $\lambda$ $\leq$8 $\micron$) and some measurable excess emission at 24 $\micron$. A sub-classof disks exhibit no significant excess emission at $\lambda \leq$ 5.8$\micron$, have excess emission only in the {\it Spitzer} 8 $\micron$ band andno detection at 24 $\micron$. We discuss these spectral energy distribution(SED) types, suggest physical models for disks exhibiting these emissionpatterns and additional observations to test these theories.

Disk Evolution in W5: Intermediate Mass Stars at 2-5 Myr