Infrared Absorption Spectra of Deuterated Amorphous Carbon

We analyze the spectral appearance of gaps occurring in circumstellar disks possibly indicating the presence of a protoplanetary or planetary object. Based on the standard parameterized disk model, we explore the 10-parameter space of possible disk configurations and properties to identify the parameter ranges where the ratio of the continuum flux from disks without and with a gap is maximum. The exploration is performed with a Monte Carlo search; the maxima are found using a simulated annealing algorithm. The strongest influence on the spectra occurs for wavelengths ranging from 10 to 300 (mu)m, with a maximum flux ratio of 1.5 for a single-planet gap and 2.5 for a double-planet gap, respectively. Analyzing the resulting spectra, we conclude that, investigating spectral energy distributions without spectral dust features, gaps typically caused by planets cannot be detected as a prominent feature.