HD 135344B multi-epoch images

We also reprocess archival JWST/NIRCam datasets with these algorithms. We measure an average spiral orbital motion of 0.81+/-0.05deg/year, in agreement with the literature value of about 0.85 deg/year at all wavelengths. With simple modeling of the twist morphology, we confirm that it is indeed co-moving with the spiral in which it is embedded.

While the position angle of the twist coincides with the dust filament, it is located at a smaller angular separation from the star, which we attribute to the fact that the spiral trace moves away from the central star with increasing wavelength. We find that a previously claimed protoplanet candidate in the disk can be adequately explained as a post-processing artifact. Our confirmation that the motion of the scattered light twist is consistent with the orbital velocity of a planet at 69+-4 au over a 10-year baseline suggests that the spirals, the gap and the dust filament in the sub-mm continuum, as well as the twist in scattered light, could indeed all be attributed to the same hypothetical protoplanet deeply embedded within the spiral.

A perplexing trend for a wavelength-dependence of the angular distance of the spiral traces to the central star still remains to be explained.