Transmission spectrum of the coadded sodium D₁ + D₂ shown in velocity space for WASP-8b (acting as a control star, in black) and WASP-49b (in red), both binned by 15 ×. A sodium absorption is present in both rest frames for WASP-49b, but slightly more significant in the planet rest frame, as expected for a planetary signature. Both stars are classified G6V and share common properties, except that WASP-8b is much more active, which could possibly lead to spurious sodium signatures of stellar origin. However, no sodium signal can be seen in WASP-8b in spite of its high activity level. Thus it is not likely that the sodium signal of WASP-49 has a stellar activity origin.