Molecules with ALMA at Planet-forming Scales (MAPS). III. Characteristics of radial chemical substructures

Charles J. Law*, Ryan A. Loomis, Richard Teague, Karin I. Öberg, Ian Czekala, Sean M. Andrews, Jane Huang, Yuri Aikawa, Felipe Alarcón, Jaehan Bae, Edwin A. Bergin, Jennifer B. Bergner, Yann Boehler, Alice S. Booth, Arthur D. Bosman, Jenny K. Calahan, Gianni Cataldi, L. Ilsedore Cleeves, Kenji Furuya, Viviana V. GuzmánJohn D. Ilee, Romane Le Gal, Yao Liu, Feng Long, François Ménard, Hideko Nomura, Chunhua Qi, Kamber R. Schwarz, Anibal Sierra, Takashi Tsukagoshi, Yoshihide Yamato, Merel L. R. van't Hoff, Catherine Walsh, David J. Wilner, Ke Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

62 Citations (Scopus)

Abstract

The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a detailed, high-resolution (~10-20 au) view of molecular line emission in five protoplanetary disks at spatial scales relevant for planet formation. Here we present a systematic analysis of chemical substructures in 18 molecular lines toward the MAPS sources: IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. We identify more than 200 chemical substructures, which are found at nearly all radii where line emission is detected. A wide diversity of radial morphologies-including rings, gaps, and plateaus-is observed both within each disk and across the MAPS sample. This diversity in line emission profiles is also present in the innermost 50 au. Overall, this suggests that planets form in varied chemical environments both across disks and at different radii within the same disk. Interior to 150 au, the majority of chemical substructures across the MAPS disks are spatially coincident with substructures in the millimeter continuum, indicative of physical and chemical links between the disk midplane and warm, elevated molecular emission layers. Some chemical substructures in the inner disk and most chemical substructures exterior to 150 au cannot be directly linked to dust substructure, however, which indicates that there are also other causes of chemical substructures, such as snowlines, gradients in UV photon fluxes, ionization, and radially varying elemental ratios. This implies that chemical substructures could be developed into powerful probes of different disk characteristics, in addition to influencing the environments within which planets assemble. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Original languageEnglish
Article number3
Number of pages46
JournalAstrophysical Journal Supplement Series
Volume257
Issue number1
Early online date3 Nov 2021
DOIs
Publication statusPublished - Nov 2021

Keywords

  • Protoplanetary disks
  • Planet formation
  • Interstellar molecules
  • Astrochemistry
  • High angular resolution

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