ALMA Detection of Dust Trapping around Lagrangian Points in the LkCa 15 Disk

Abstract

We present deep high-resolution ($\sim$50 mas, 8 au) ALMA 0.88 and 1.3 mm continuum observations of the LkCa 15 disk. The emission morphology shows an inner cavity and three dust rings at both wavelengths, but with slightly narrower rings at the longer wavelength. Along a faint ring at 42 au, we identify two excess emission features at $\sim$10$\sigma$ significance at both wavelengths: one as an unresolved clump and the other as an extended arc, separated by roughly 120 degrees in azimuth. The clump is unlikely to be a circumplanetary disk (CPD) as the emission peak shifts between the two wavelengths even after accounting for orbital motion. Instead, the morphology of the 42 au ring strongly resembles the characteristic horseshoe orbit produced in planet--disk interaction models, where the clump and the arc trace dust accumulation around Lagrangian points $L_4$ and $L_5$, respectively. The shape of the 42 au ring, dust trapping in the outer adjacent ring, and the coincidence of the horseshoe ring location with a gap in near-IR scattered light, are all consistent with the scenario of planet sculpting, with the planet likely having a mass between those of Neptune and Saturn. We do not detect point-like emission associated with a CPD around the putative planet location ($0{.}^{\prime \prime }27$ in projected separation from the central star at a position angle of $\sim$60\degr), with upper limits of 70 and 33 $\mu$Jy at 0.88 and 1.3 mm, respectively, corresponding to dust mass upper limits of 0.02--0.03 $M_{\oplus }$.

ApJL in press

References in corpus (26)

• Ring shaped dust accumulation in transition disks
• A Circumplanetary Disk Around PDS70c
• Multiple Disk Gaps and Rings Generated by a Single Super-Earth
• Submillimeter emission associated with candidate protoplanets
• Standing on the shoulders of giants: Trojan Earths and vortex trapping in low mass self-gravitating protoplanetary disks of gas and solids
• Images of Embedded Jovian Planet Formation At A Wide Separation Around AB Aurigae
• The newborn planet population emerging from ring-like structures in discs
• On the formation of multiple concentric rings and gaps in protoplanetary disks
• Dust unveils the formation of a mini-Neptune planet in a protoplanetary ring
• No Clear, Direct Evidence for Multiple Protoplanets Orbiting LkCa 15: LkCa 15 bcd are Likely Inner Disk Signals
• Searching for circumplanetary disks around LkCa 15
• Frankenstein: Protoplanetary disc brightness profile reconstruction at sub-beam resolution with a rapid Gaussian process
• Resolving the planet-hosting inner regions of the LkCa 15 disk
• Perturbers: SPHERE detection limits to planetary-mass companions in protoplanetary disks
• Annular substructures in the transition disks around LkCa 15 and J1610
• Molecules with ALMA at Planet-forming Scales (MAPS). A Circumplanetary Disk Candidate in Molecular Line Emission in the AS 209 Disk
• Limits on Millimeter Continuum Emission from Circumplanetary Material in the DSHARP Disks
• Gas temperature structure across transition disk cavities
• A super-resolution analysis of the DSHARP survey: Substructure is common in the inner 30 au
• Dual-Wavelength ALMA Observations of Dust Rings in Protoplanetary Disks
• Vortex-like kinematic signal, spirals, and beam smearing effect in the HD 142527 disk
• Planet-Disk Interactions
• Dust trapping around Lagrangian points in protoplanetary disks
• Optical and Near-infrared View of Planet-forming Disks and Protoplanets
• Modeling the nonaxisymmetric structure in the HD 163296 disk with planet-disk interaction
• ALMA Discovery of a Disk around the Planetary-mass Companion SR 12 c

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• Protoplanetary disks in $K_s$-band total intensity and polarized light
• exoALMA V: Gaseous Emission Surfaces and Temperature Structures
• exoALMA IV: Substructures, Asymmetries, and the Faint Outer Disk in Continuum Emission
• Stellar Flyby Analysis for Spiral Arm Hosts with Gaia DR3
• A localized kinematic structure detected in atomic carbon emission spatially coincident with a proposed protoplanet in the HD 163296 disk
• Tentative co-orbital submillimeter emission within the Lagrangian region L5 of the protoplanet PDS 70 b
• Systematic Multi-Epoch Monitoring of LkCa 15: Dynamic Dust Structures on Solar-System Scales
• A gap-sharing planet pair shaping the crescent in HD 163296: a disk sculpted by a resonant chain
• Distinguishing Magnetized Disc Winds from Turbulent Viscosity through Substructure Morphology in Planet-forming Discs
• Vertical CO surfaces as a probe for protoplanetary disk mass and carbon depletion
• A Large Double-ring Disk around the Taurus M Dwarf J04124068+2438157
• Astrometric view of companions in the inner dust cavities of protoplanetary disks
• The Dynamics of Co-orbital Giant Exomoons -- Applications for the Kepler-1625 b and Kepler-1708 b Satellite Systems
• exoALMA XXIII. Estimating Disk and Planet Properties from Dust Morphologies with DBNets2.0