The Signature of Primordial Grain Growth in the Polarized Light of the AU Mic Debris Disk

Abstract

We have used the Hubble Space Telescope/ACS coronagraph to make polarization maps of the AU Mic debris disk. The fractional linear polarization rises monotonically from about 0.05 to 0.4 between 20 and 80 AU. The polarization is perpendicular to the disk, indicating that the scattered light originates from micron sized grains in an optically thin disk. Disk models, which simultaneously fit the surface brightness and polarization, show that the inner disk (< 40-50 AU) is depleted of micron-sized dust by a factor of more than 300, which means that the disk is collision dominated. The grains have high maximum linear polarization and strong forward scattering. Spherical grains composed of conventional materials cannot reproduce these optical properties. A Mie/Maxwell-Garnett analysis implicates highly porous (91-94%) particles. In the inner Solar System, porous particles form in cometary dust, where the sublimation of ices leaves a "bird's nest" of refractory organic and silicate material. In AU Mic, the grain porosity may be primordial, because the dust "birth ring" lies beyond the ice sublimation point. The observed porosities span the range of values implied by laboratory studies of particle coagulation by ballistic cluster-cluster aggregation. To avoid compactification, the upper size limit for the parent bodies is in the decimeter range, in agreement with theoretical predictions based on collisional lifetime arguments. Consequently, AU Mic may exhibit the signature of the primordial agglomeration process whereby interstellar grains first assembled to form macroscopic objects.

12 pages, 8 figures, ApJ, in press

References in corpus (3)

• HST/ACS Multiband Coronagraphic Imaging of the Debris Disk around Beta Pictoris
• On the AU Mic debris disk: density profiles, grain properties and dust dynamics
• First Two-Micron Imaging Polarimetry of Beta Pictoris

Cited by in corpus (101)

• Discovery of Small-Scale Spiral Structures in the Disk of SAO 206462 (HD 135344B): Implications for the Physical State of the Disk from Spiral Density Wave Theory
• Debris Disks: Structure, Composition, and Variability
• Probing for Exoplanets Hiding in Dusty Debris Disks: Disk Imaging, Characterization, and Exploration with HST/STIS Multi-Roll Coronagraphy
• Polarimetry with the Gemini Planet Imager: Methods, Performance at First Light, and the Circumstellar Ring around HR 4796A
• Probing dust grain evolution in IM Lupi's circumstellar disc. Multi-wavelength observations and modelling of the dust disc
• Debris Disks: Seeing Dust, Thinking of Planetesimals and Planets
• $\beta$ Pictoris' inner disk in polarized light and new orbital parameters for $\beta$ Pictoris b
• An icy Kuiper-Belt around the young solar-type star HD 181327
• Spitzer/MIPS Observations of Stars in the Beta Pictoris Moving Group
• Herschel images of Fomalhaut. An extrasolar Kuiper Belt at the height of its dynamical activity
• Millimeter Emission Structure in the first ALMA Image of the AU Mic Debris Disk
• Discovery of extreme asymmetry in the debris disk surrounding HD 15115
• High-Contrast Observations in Optical and Infrared Astronomy
• VLT/NACO Polarimetric Differential Imaging of HD100546 - Disk Structure and Dust Grain Properties between 10-140 AU
• Speckle Suppression Through Dual Imaging Polarimetry, and a Ground-Based Image of the HR 4796A Circumstellar Disk
• Interstellar Medium Sculpting of the HD 32297 Disk
• The Case of AB Aurigae's Disk in Polarized Light: Is There Truly a Gap?
• Modeling Porous Dust Grains with Ballistic Aggregates. II. Light Scattering Properties
• The AU Microscopii Debris Disk: Multiwavelength Imaging and Modeling
• Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti
• Modeling Self-Subtraction in Angular Differential Imaging: Application to the HD 32297 Debris Disk
• Modeling the HD32297 Debris Disk with Far-IR Herschel Data
• Five Debris Disks Newly Revealed in Scattered Light from the HST NICMOS Archive
• Impact of grain evolution on the chemical structure of protoplanetary disks
• Constraints on Planetesimal Collision Models in Debris Disks
• Hubble and Spitzer Space Telescope Observations of the Debris Disk around the Nearby K Dwarf HD 92945
• Observations of fast-moving features in the debris disk of AU Mic on a three-year timescale: Confirmation and new discoveries
• Long-lived planetesimal discs
• Hubble Space Telescope Optical Imaging of the Eroding Debris Disk HD 61005
• Non-Detection of Polarized, Scattered Light from the HD 189733b Hot Jupiter
• Optical polarized phase function of the HR\,4796A dust ring
• Solar System Analogs Around IRAS-Discovered Debris Disks
• Collisional modelling of the AU Microscopii debris disc
• A Resolved Millimeter Emission Belt in the AU Mic Debris Disk
• The AU Mic Debris Disk: far-infrared and submillimeter resolved imaging
• ALMA Detection of Extended Millimeter Halos in the HD 32297 and HD 61005 Debris Disks
• Mass and Temperature of the TWA 7 Debris Disk
• How large are the monomers of dust aggregates in planet-forming disks?: Insights from quantitative optical and near-infrared polarimetry
• Polarized Light Imaging of the HD 142527 Transition Disk with the Gemini Planet Imager: Dust around the Close-in Companion
• SPH simulations of grain growth in protoplanetary disks
• The HIP 79977 debris disk in polarized light
• Gemini Planet Imager Observations of the AU Microscopii Debris Disk: Asymmetries within One Arcsecond
• Exocomets from a Solar System Perspective
• The intrinsic and interstellar broadband linear polarization of nearby FGK dwarfs
• Retrieving Dust Grain Sizes from Photopolarimetry: An Experimental Approach
• The Peculiar Debris Disk of HD 111520 as Resolved by the Gemini Planet Imager
• The PDS 66 Circumstellar Disk as seen in Polarized Light with the Gemini Planet Imager
• Bringing "The Moth" to Light: A Planet-Sculpting Scenario for the HD 61005 Debris Disk
• Direct Imaging of the HD 35841 Debris Disk: A Polarized Dust Ring from Gemini Planet Imager and an Outer Halo from HST/STIS
• The challenge of measuring the phase function of debris disks. Application to HR\,4796
• Formation and evolution of planetary systems: the impact of high angular resolution optical techniques
• Discovery of an extended debris disk around the F2V star HD 15745
• A Ring of Warm Dust in the HD 32297 Debris Disk
• Investigating the presence of two belts in the HD 15115 system
• Stellar Winds and Dust Avalanches in the AU Mic Debris Disk
• New constraints on the dust surrounding HR 4796A
• Subaru/HiCIAO $H{K}_{\mathrm{s}}$ imaging of LkH$\alpha$ 330 - multi-band detection of the gap and spiral-like structures
• A Submillimetre Search for Cold Extended Debris Disks in the Beta Pictoris Moving Group
• Circumstellar disks and planets. Science cases for next-generation optical/infrared long-baseline interferometers
• The Gemini Planet Imager view of the HD 32297 debris disk
• SCExAO/CHARIS Near-IR High-Contrast Imaging and Integral Field Spectroscopy of the HIP 79977 Debris Disk
• VLT/SPHERE Multi-Wavelength High-Contrast Imaging of the HD 115600 Debris Disk: New Constraints on the Dust Geometry and the Presence of Young Giant Planets
• Resolving The Moth at Millimeter Wavelengths
• Imaging an 80 AU Radius Dust Ring Around the F5V Star HD 157587
• Comprehensive analysis of HD 105, a young Solar System analog
• The long-period Galactic Cepheid RS Puppis - III. A geometric distance from HST polarimetric imaging of its light echoes
• Characterizing the morphology of the debris disk around the low-mass star GSC~07396-00759
• Calibration of the Liverpool Telescope RINGO3 polarimeter
• Quantitative polarimetry of the disk around HD 169142
• Multiwavelength Vertical Structure in the AU Mic Debris Disk: Characterizing the Collisional Cascade
• High Fidelity Imaging of the Inner AU Mic Debris Disk: Evidence of Differential Wind Sculpting?
• HD 117214 debris disk: scattered-light images and constraints on the presence of planets
• Rave: A non-parametric method for recovering the surface brightness and height profiles of edge-on debris disks
• The IRCAL Polarimeter: Design, Calibration, and Data Reduction for an Adaptive Optics Imaging Polarimeter
• X-raying the AU Microscopii debris disk
• Stumbling over planetary building blocks: AU Microscopii as an example of the challenge of retrieving debris-disk dust properties
• The high-albedo, low polarization disk around HD 114082 harbouring a Jupiter-sized transiting planet
• The Kuiper Belt and Other Debris Disks
• Polarimetric and radiative transfer modelling of HD 172555
• Optical Coronagraphic Spectroscopy of AU Mic: Evidence of Time Variable Colors?
• Light Scattering and Thermal Emission by Primitive Dust Particles in Planetary Systems
• Linking studies of tiny meteoroids, zodiacal dust, cometary dust and circumstellar disks
• Polarization of stars with debris disks: comparing observations with models
• Probing the innermost region of the AU~Microscopii debris disk
• Polarization measurements of the polluted white dwarf G29-38
• Characterization of debris disks observed with SPHERE
• Radiative Transfer Models of a Possible Planet in the AB Aurigae Disk
• The Mysterious Affair of the H${}_2$ in AU Mic
• Quadrant polarization parameters for the scattered light of circumstellar disks. Analysis of debris disk models and observations of HR 4796A
• Multi-wavelength aperture polarimetry of debris disc host stars
• ALMA's view of the M-dwarf GSC 07396-00759's edge-on debris disc: AU Mic's coeval twin
• Dust Production Rates in the Fomalhaut Debris Disk from SOFIA/FORCAST Mid-infrared Imaging
• Polarimetric coronagraphy of BD+31643
• Sensitivity of Polarization to Grain Shape: II. Aggregates
• Simulations of polarimetric observations of debris disks through the Roman Coronagraph Instrument
• O/IR Polarimetry for the 2010 Decade (GAN): Science at the Edge, Sharp Tools for All
• WFIRST-AFTA Coronagraphic Operations: Lessons Learned from the Hubble Space Telescope and the James Webb Space Telescope
• Resolution and calibration effects in high contrast polarimetric imaging of circumstellar scattering regions
• What you see is not necessarily what you get: Interpreting near-infrared scattering phase functions of debris discs
• Adaptive Optics Observations of Exoplanets, Brown Dwarfs, & Binary Stars
• O/IR Polarimetry for the 2010 Decade (CGT): Science at the Edge, Sharp Tools for All