Mid-infrared evidence for iron-rich dust in the multi-ringed inner disk of HD 144432

Abstract

Context. Rocky planets form by the concentration of solid particles in the inner few au regions of planet-forming disks. Their chemical composition reflects the materials in the disk available in the solid phase at the time the planets were forming. Aims. We aim to constrain the structure and dust composition of the inner disk of the young star HD 144432, using an extensive set of infrared interferometric data taken by the Very Large Telescope Interferometer (VLTI), combining PIONIER, GRAVITY, and MATISSE observations. Methods. We introduced a new physical disk model, TGMdust, to image the interferometric data, and to fit the disk structure and dust composition. We also performed equilibrium condensation calculations with GGchem. Results. Our best-fit model has three disk zones with ring-like structures at 0.15, 1.3, and 4.1 au. Assuming that the dark regions in the disk at ~0.9 au and at ~3 au are gaps opened by planets, we estimate the masses of the putative gap-opening planets to be around a Jupiter mass. We find evidence for an optically thin emission ($\tau <0.4$) from the inner two disk zones ($r<4$ au) at $\lambda >3\mu$m. Our silicate compositional fits confirm radial mineralogy gradients. To identify the dust component responsible for the infrared continuum emission, we explore two cases for the dust composition, one with a silicate+iron mixture and the other with a silicate+carbon one. We find that the iron-rich model provides a better fit to the spectral energy distribution. Conclusions. We propose that in the warm inner regions ($r<5$ au) of typical planet-forming disks, most if not all carbon is in the gas phase, while iron and iron sulfide grains are major constituents of the solid mixture along with forsterite and enstatite. Our analysis demonstrates the need for detailed studies of the dust in inner disks with new mid-infrared instruments such as MATISSE and JWST/MIRI.

29 pages, 24 figures. Equation 4 has been corrected, as there was a sign error in the original version

References in corpus (33)

• The Gaia mission
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• The evolution of amorphous hydrocarbons in the ISM: dust modelling from a new vantage point
• Ring shaped dust accumulation in transition disks
• Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simulations to ALMA Observations
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• Mass Estimates of a Giant Planet in a Protoplanetary Disk from the Gap Structures
• Collisional processes and size distribution in spatially extended debris discs
• Structure of Herbig AeBe disks at the milliarcsecond scale A statistical survey in the H band using PIONIER-VLTI
• MINDS. The detection of ${}^{13}$CO${}_2$ with JWST-MIRI indicates abundant CO${}_2$ in a protoplanetary disk
• Refining the Census of the Upper Scorpius Association with Gaia
• Water in the terrestrial planet-forming zone of the PDS 70 disk
• Thermal imaging of dust hiding the black hole in the Active Galaxy NGC 1068
• Polarized disk emission from Herbig Ae/Be stars observed using Gemini Planet Imager: HD 144432, HD 150193, HD 163296, and HD 169142
• Homogeneous study of Herbig Ae/Be stars from spectral energy distributions and Gaia EDR3
• Accretion-related properties of Herbig Ae/Be stars. Comparison with T Tauris
• Possible evidence of ongoing planet formation in AB Aurigae. A showcase of the SPHERE/ALMA synergy
• Perturbers: SPHERE detection limits to planetary-mass companions in protoplanetary disks
• The GRAVITY Young Stellar Object survey -- I. Probing the disks of Herbig Ae/Be stars in terrestrial orbits
• Polycyclic Aromatic Hydrocarbon in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars
• Hydro-, Magnetohydro-, and Dust-Gas Dynamics of Protoplanetary Disks
• Investigating dust trapping in transition disks with millimeter-wave polarization
• JWST/MIRI Spectroscopy of the Disk of the Young Eruptive Star EX Lup in Quiescence
• Nucleation and growth of iron pebbles explains the formation of iron-rich planets akin to Mercury
• The asymmetric inner disk of the Herbig Ae star HD 163296 in the eyes of VLTI/MATISSE: evidence for a vortex?
• The GRAVITY Young Stellar Object survey. VII. The inner dusty disks of T Tauri stars
• Substructure Formation in a Protostellar Disk of L1527 IRS
• Dust Formation in Astrophysical Environments: The Importance of Kinetics
• Forming planets around stars with non-solar elemental composition
• Discovery of stars surrounded by iron dust in the LMC
• Chemical and physical properties of cometary dust
• Spatially resolving the chemical composition of the planet building blocks

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