The spectral energy distributions of classical Cepheids in the Magellanic Clouds

The spectral energy distributions (SEDs) of a sample of 142 LMC and 77 SMC fundamental mode classical Cepheids (CCs) were constructed using photometric data in the literature. The sample was build from stars that have a metallicity determination from high-resolution spectroscopy, have been used in Baade-Wesselink type of analysis, have a radial velocity curve published in {\it Gaia} DR3, have Walraven photometry, or have their light- and radial-velocity curves modelled by pulsation codes. The SEDs were fitted with stellar photosphere models to derive the best-fitting luminosity and effective temperature. Distance and reddening were taken from the literature. Only one star with a significant infrared (IR) excess was found in the LMC and none in the SMC, contrary to earlier work on the Milky Way (MW) suggesting that IR excess may be more prominent in MW cepheids than in the Magellanic Clouds. The stars were plotted in a Hertzsprung-Russell diagram (HRD) and compared to evolutionary tracks for CCs and to theoretical instability strips. For the large majority of stars, the position in the HRD is consistent with the instability strip. Period-luminosity ($PL$) and period-radius relations are derived and compared to these relations in the MW.