2025AJ....169..287U

HD 163296 is a Herbig Ae/Be star with multiple signposts of ongoing planet formation on its disk, such as prominent rings and gaps, as well as kinematic features as identified by previous Atacama Large Millimeter/submillimeter Array (ALMA) observations. We carried out JWST/NIRCam coronagraphic imaging using the F410M and F200W NIRCam filters, with the goal of detecting the emission from the putative young planets in this system. Our F410M observations did not detect the putative planets at the predicted locations of the ALMA velocity kinks, but they did detect a point-like source candidate at a separation of $\approx 0\mathop{.}\limits^{^{\prime\prime} }75$ and a position angle of $\approx 231\mathop{.}\limits^{^\circ }4$ that is unlikely a background star because of the measured flux in the F410M filter and the detection limit in the F200W filter. These data achieved unprecedented contrast levels at ∼4 μm at stellocentric separations $\rho \gtrsim 0\mathop{.}\limits^{^{\prime\prime} }8$. This allowed us to derive stringent constraints at the outer velocity kink (ΔF410M = 15.2 mag) on the mass of the putative planet with or without a circumplanetary disk, and considering different possible initial entropies for the planet.