Camryn Mullin

As the nearest protoplanetary disk to Earth ( d = 60.14 pc), TW Hya is one of the most studied protoplanetary disks and a critical benchmark for testing planet formation theories. We present high-contrast coronagraphic imaging of the TW Hya disk from JWST/NIRCam across four filters (F187N, F200W, F356W, and F444W). We detect the disk’s scattered-light emission in F200W, F356W, and F444W. An elliptical fit to the disk image yields an average inclination of i = 8 . ° 74 − 0 . ° 94 + 1 . ° 03 and a position angle of PA = 75 . ° 62 − 6 . ° 56 + 7 . ° 86 . We find tentative evidence for radial variations in these parameters, a trend consistent with a disk warp. Our companion search yields no new detections, placing the lowest mass limits yet on companions that might be responsible for carving out the dust gap. Assuming no local extinction and a system age of 10 Myr, the F444W data are sensitive to masses down to ∼0.4 M _Jup at separations of 1″ (∼60 au). Accounting for local disk extinction analogous to the AS 209 system, our limits reach sub-Jupiter masses beyond 2″. Furthermore, our analysis provides a detailed view of a previously detected feature in the outer disk at ∼120 au, confirming its morphology as a distinct bifurcation structure. This feature may indicate the presence of complex substructures arising from dynamical planet–disk interactions. These results demonstrate JWST’s ability to characterize the architecture of protoplanetary disks and constrain the properties of forming worlds.

Using the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument, we present near-infrared K -band polarimetric imaging of nine Herbig stars selected from a volume-limited sample within 200 pc. We detect the disks around MWC 480, HD 163296, and HD 143006 for the first time with SCExAO, and compare these observations with previous Very Large Telescope/SPHERE datasets to identify surface-brightness variability. In MWC 480, we resolve two azimuthal brightness dips near the disk minor axis and find evidence that one of them shifted between 2021 and 2022. In HD 163296, we identify an apparent linear azimuthal motion of a localized peak in polarized intensity along the outer ring over a 15 month baseline. The rapid motion of these features relative to the local Keplerian velocity suggests that the observed variability is driven by changing illumination rather than physical material motion. Due to uncertainties in the underlying scattering background, however, we cannot determine the precise physical origin of the variability. No significant disk variability is detected in HD 143006 over a 10 month baseline. We also report the first detection of a protoplanetary disk using the fast polarimetric differential imaging mode on SCExAO, illustrating both the promise and current limitations of this observing mode. Finally, we report nondetections toward HD 144432, HD 56895, PDS 76, HIP 80425, HD 148352, and HIP 81474. All nondetections with Meeus classifications belong to Group II systems and are likely self-shadowed. For these six systems, we measure the system-integrated polarization fraction and angle of linear polarization, providing quantitative constraints on their unresolved circumstellar environments.

As part of the James Webb Space Telescope (JWST) Guaranteed Time Observation program “Direct Imaging of YSOs” (program ID 1179), we use JWST NIRCam’s direct imaging mode in F187N, F200W, F405N, and F410M to perform high-contrast observations of the circumstellar structures surrounding the protostar HL Tau. The data reveal the known stellar envelope, outflow cavity, and streamers, but do not detect any companion candidates. We detect scattered light from an inflowing spiral streamer previously detected in HCO⁺ by the Atacama Large Millimeter/submillimeter Array, and part of the structure connected to the c-shaped outflow cavity. For detection limits in planet mass we use BEX evolutionary tracks when M _p < 2 M _J and AMES-COND evolutionary tracks otherwise, assuming a planet age of 1 Myr (youngest available age). Inside the disk region, due to extended envelope emission, our point-source sensitivities are ∼5 mJy (37 M _J) at 40 au in F187N and ∼0.37 mJy (5.2 M _J) at 140 au in F405N. Outside the disk region, the deepest limits we can reach are ∼0.01 mJy (0.75 M _J) at a projected separation ∼ 525 au.

We present JWST/NIRCam F187N, F200W, F405N, and F410M direct imaging data of the disk surrounding SAO 206462. Previous images show a very structured disk, with a pair of spiral arms thought to be launched by one or more external perturbers. The spiral features are visible in three of the four filters, with the nondetection in F410M due to the large detector saturation radius. We detect with a signal-to-noise ratio of 4.4 a companion candidate that, if on a coplanar circular orbit, would orbit SAO 206462 at a separation of ∼300 au, 2.25σ away from the predicted separation for the driver of the eastern spiral. No other companion candidates were detected. At the location predicted by simulations of both spirals generated by a single massive companion, the NIRCam data exclude objects more massive than ∼2.2 M _J assuming the BEX evolutionary models. In terms of temperatures, the data are sensitive to objects with T _eff ∼ 650–850 K, when assuming planets emit like blackbodies (R _p between 1 and 3R _J). From these results, we conclude that if the spirals are driven by gas giants, these must be either cold or embedded in circumplanetary material. In addition, the NIRCam data provide tight constraints on ongoing accretion processes. In the low extinction scenario we are sensitive to mass accretion rates of the order M ̇ ∼ 10 − 9 M J yr⁻¹. Thanks to the longer wavelengths used to search for emission lines, we reach unprecedented sensitivities to processes with M ̇ ∼ 10 − 7 M J yr⁻¹ even toward highly extincted environments (A _V ≈ 50 mag).