SED of R Aqr described by single-band photometry (filled squares) compiled from the literature as well as the available ISO-SWS (blue line) and -LWS (cyan line) spectra. Overplotted are the synthetic spectra based on models for the photosphere (MARCS; green line) and the combined photosphere + wind (red line; see Section 4.1.2 for details). In addition, aperture photometry of the PACS 70 μm and 160 μm bands (triangles) is included. There are three data points for each of these measurements. From bottom to top: aperture photometry (i) of the eastern arm; (ii) of the central source; and (iii) of the whole IR-emitting region. The dotted line represents the model for the dust emission of the eastern arm.