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Abstract We present the first interferometric imaging of molecular line emission from the Ring Nebula, NGC 6720, in the form of Submillimeter Array (SMA) observations of COJ = 2 → 1 emission. The SMA¹²CO(2–1) mapping data, with ∼3″ spatial resolution and 2 km s⁻¹velocity resolution, provide an unprecedentedly detailed, 3D view of the Ring’s clumpy molecular envelope. The emission morphology displayed in the velocity-integrated SMA¹²CO(2–1) image closely resembles the morphologies of near-IR H₂and polycyclic aromatic hydrocarbon emission as revealed in recent JWST/NIRCam imaging of NGC 6720. The SMA¹²CO(2–1) data demonstrate that the molecular gas is found within a geometrically thin layer that immediately surrounds the ionized gas imaged by Hubble Space Telescope and JWST. A simple, geometric model of the¹²CO(2–1) emission data shows that the intrinsic structure of NGC 6720’s molecular envelope closely resembles a truncated, triaxial ellipsoid that is viewed close to pole-on, and that the dynamical age of the molecular envelope is ∼6000 yr. The SMA¹²CO(2–1) mapping data furthermore reveal that some of the faint, filamentary features seen projected in the Ring’s interior in JWST imaging are in fact fast-moving polar knots or bullets with radial velocities of ±45–50 km s⁻¹relative to the systemic velocity, and that the hot progenitor star remnant is positioned at the precise geometric center of the clumpy, ellipsoidal molecular shell. We assert that the Ring’s molecular envelope represents the “fossil” remnant of a relatively sudden mass ejection ∼6000 yr ago that terminated the progenitor star’s asymptotic giant branch (AGB) evolution, and that this ellipsoidal envelope of AGB ejecta was then punctured by fast, collimated polar outflows or jets resulting from interactions between the progenitor and one or more companion stars. Such an evolutionary scenario may describe most if not all molecule-rich, “Ring-like” planetary nebulae. 

Abstract We present a provisory scattered-light detection of the Vega debris disk using deep Hubble Space Telescope (HST) coronagraphy (PID 16666). At only 7.7 pc, Vega is immensely important in debris disk studies both for its prominence and also because it allows the highest physical resolution among all debris systems relative to temperature zones around the star. We employ the STIS coronagraph’s widest wedge position and classical reference differential imaging to achieve among the lowest surface-brightness sensitivities to date ( $\sim 4\mu {\mathrm{Jy}\mathrm{arcsec}}^{-2}$) at wide separations using 32 orbits in Cycle 29. We detect a halo extending from the inner edge of our effective inner working angle at 10.″5 out to the photon noise floor at 30″ (80–230 au). The face-on orientation of the system and the lack of a perfectly color-matched point-spread function star have posed significant challenges to the reductions, particularly regarding artifacts from the imperfect color matching. However, we find that a halo of small dust grains provides the best explanation for the observed signal. Unlike Fomalhaut (a close twin to Vega in luminosity, distance, and age), there is no clear distinction in scattered light between the parent planetesimal belt observed with the Atacama Large Millimeter/submillimeter Array and the extended dust halo. These HST observations complement JWST GTO Cycle 1 observations of the system with NIRCam and MIRI. 

Abstract Ionization drives important chemical and dynamical processes within protoplanetary disks, including the formation of organics and water in the cold midplane and the transportation of material via accretion and magnetohydrodynamic flows. Understanding these ionization-driven processes is crucial for understanding disk evolution and planet formation. We use new and archival Atacama Large Millimeter/submillimeter Array observations of HCO⁺, H¹³CO⁺, and N₂H⁺to produce the first forward-modeled 2D ionization constraints for the DM Tau protoplanetary disk. We include ionization from multiple sources and explore the disk chemistry under a range of ionizing conditions. Abundances from our 2D chemical models are postprocessed using non-LTE radiative transfer, visibility sampling, and imaging, and are compared directly to the observed radial emission profiles. The observations are best fit by a modestly reduced cosmic-ray ionization rate (ζ_CR∼10⁻¹⁸s⁻¹) and a hard X-ray spectrum (hardness ratio = 0.3), which we associate with stellar flaring conditions. Our best-fit model underproduces emission in the inner disk, suggesting that there may be an additional mechanism enhancing ionization in DM Tau’s inner disk. Overall, our findings highlight the complexity of ionization in protoplanetary disks and the need for high-resolution multiline studies. 

Abstract 2MASS J16120668–3010270 (hereafter 2MJ1612) is a young M0 star that hosts a protoplanetary disk in the Upper Scorpius star-forming region. Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations of 2MJ1612 show a mildly inclined disk (i = 37°) with a large dust-depleted gap (R_cav ≈ 0 $\stackrel{\text{″}}{.}$4 or 53 au). We present high-contrast Hαobservations from MagAO-X on the 6.5 m Magellan telescope and new high-resolution submillimeter dust continuum observations with ALMA of 2MJ1612. On both 2025 April 13 and 16, we recovered a point source with Hαexcess with a signal-to-noise ratio ≳5 within the disk gap in our MagAO-X angular and spectral differential images at a separation of 141.96 ± 2.10 mas (23.45 ± 0.29 au deprojected) from the star and a position angle ​​​​​of 159 $\stackrel{\text{°}}{.}$00 ± 0 $\stackrel{\text{°}}{.}$55. Furthermore, this Hαsource is within close proximity to aK-band point source in the SPHERE/IRDIS observation taken on 2023 July 21. The astrometric offset between theKband and Hαsource can be explained by orbital motion of a bound companion. Thus, our observations can be best explained by the discovery of an accreting protoplanet, 2MJ1612 b, with an estimated mass of 4M_Jupand a Hαline flux ranging from (29.7 ± 7.5) × 10⁻¹⁶erg s cm²to (8.2 ± 3.4) × 10⁻¹⁶erg s cm². 2MJ1612 b is likely the third example of an accreting Hαprotoplanet responsible for carving the gap in its host disk, joining PDS 70 b and c. Further study is necessary to confirm and characterize this protoplanet candidate and to identify any additional protoplanets that may also play a role in shaping the gap. 

Abstract We study the kinematics of the AS 209 disk using theJ= 2–1 transitions of¹²CO,¹³CO, and C¹⁸O. We derive the radial, azimuthal, and vertical velocity of the gas, taking into account the lowered emission surface near the annular gap at ≃1.″7 (200 au) within which a candidate circumplanetary-disk-hosting planet has been reported previously. In¹²CO and¹³CO, we find a coherent upward flow arising from the gap. The upward gas flow is as fast as 150 m s⁻¹in the regions traced by¹²CO emission, which corresponds to about 50% of the local sound speed or 6% of the local Keplerian speed. Such an upward gas flow is difficult to reconcile with an embedded planet alone. Instead, we propose that magnetically driven winds via ambipolar diffusion are triggered by the low gas density within the planet-carved gap, dominating the kinematics of the gap region. We estimate the ambipolar Elsässer number, Am, using the HCO⁺column density as a proxy for ion density and find that Am is ∼0.1 at the radial location of the upward flow. This value is broadly consistent with the value at which numerical simulations find that ambipolar diffusion drives strong winds. We hypothesize that the activation of magnetically driven winds in a planet-carved gap can control the growth of the embedded planet. We provide a scaling relationship that describes the wind-regulated terminal mass: adopting parameters relevant to 100 au from a solar-mass star, we find that the wind-regulated terminal mass is about one Jupiter mass, which may help explain the dearth of directly imaged super-Jovian-mass planets. 

Abstract Theoretical models and observations suggest that the abundances of molecular ions in protoplanetary disks should be highly sensitive to the variable ionization conditions set by the young central star. We present a search for temporal flux variability of HCO⁺J= 1–0, which was observed as a part of the Molecules with Atacama Large Millimeter/submillimeter Array (ALMA) at Planet-forming Scales ALMA Large Program. We split out and imaged the line and continuum data for each individual day the five sources were observed (HD 163296, AS 209, GM Aur, MWC 480, and IM Lup, with between three and six unique visits per source). Significant enhancement (>3σ) was not observed, but we find variations in the spectral profiles in all five disks. Variations in AS 209, GM Aur, and HD 163296 are tentatively attributed to variations in HCO⁺flux, while variations in IM Lup and MWC 480 are most likely introduced by differences in theuvcoverage, which impact the amount of recovered flux during imaging. The tentative detections and low degree of variability are consistent with expectations of X-ray flare-driven HCO⁺variability, which requires relatively large flares to enhance the HCO⁺rotational emission at significant (>20%) levels. These findings also demonstrate the need for dedicated monitoring campaigns with high signal-to-noise ratios to fully characterize X-ray flare-driven chemistry. 

Abstract The young and well-studied planetary nebula (PN) NGC 7027 harbors significant molecular gas that is irradiated by luminous, pointlike UV (central star) and diffuse (shocked nebular) X-ray emission. This nebula represents an excellent subject to investigate the molecular chemistry and physical conditions within photon- and X-ray-dominated regions (PDRs and XDRs). As yet, the exact formation routes of CO⁺and HCO⁺in PN environments remain uncertain. Here we present ∼2″ resolution maps of NGC 7027 in the irradiation tracers CO⁺and HCO⁺obtained with the IRAM NOEMA interferometer, along with SMA CO and HST 2.12μm H₂data for context. The CO⁺map constitutes the first interferometric map of this molecular ion in any PN. Comparison of CO⁺and HCO⁺maps reveals strikingly different emission morphologies, as well as a systematic spatial displacement between the two molecules; the regions of brightest HCO⁺, found along the central waist of the nebula, are radially offset by ∼1″ (∼900 au) outside the corresponding CO⁺emission peaks. The CO⁺emission furthermore precisely traces the inner boundaries of the nebula’s PDR (as delineated by near-IR H₂emission), suggesting that central star UV emission drives CO⁺formation. The displacement of HCO⁺radially outward with respect to CO⁺is indicative that dust-penetrating soft X-rays are responsible for enhancing the HCO⁺abundance in the surrounding molecular envelope, forming an XDR. These interferometric CO⁺and HCO⁺observations of NGC 7027 thus clearly establish the spatial distinction between the PDR and XDR formed (respectively) by intense UV and X-ray irradiation of molecular gas.