Molecules with ALMA at Planet-forming Scales (MAPS). VII. Substellar O/H and C/H and Superstellar C/O in Planet-feeding Gas - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles The Astrophysical Journal Supplement Series Year : 2021

Molecules with ALMA at Planet-forming Scales (MAPS). VII. Substellar O/H and C/H and Superstellar C/O in Planet-feeding Gas

Arthur D. Bosman
  • Function : Author
Felipe Alarcón
  • Function : Author
Edwin A. Bergin
  • Function : Author
Ke Zhang
  • Function : Author
Merel L. R. Van'T Hoff
  • Function : Author
Karin I. Öberg
  • Function : Author
Viviana V. Guzmán
  • Function : Author
Catherine Walsh
  • Function : Author
Yuri Aikawa
Sean M. Andrews
  • Function : Author
Jennifer B. Bergner
  • Function : Author
Alice S. Booth
  • Function : Author
Gianni Cataldi
  • Function : Author
L. Ilsedore Cleeves
  • Function : Author
Ian Czekala
  • Function : Author
Kenji Furuya
  • Function : Author
Jane Huang
  • Function : Author
John D. Ilee
  • Function : Author
Charles J. Law
  • Function : Author
Yao Liu
  • Function : Author
Feng Long
  • Function : Author
Ryan A. Loomis
  • Function : Author
Hideko Nomura
Chunhua Qi
Kamber R. Schwarz
  • Function : Author
Richard Teague
Takashi Tsukagoshi
Yoshihide Yamato
  • Function : Author
David J. Wilner
  • Function : Author

Abstract

The elemental composition of the gas and dust in a protoplanetary disk influences the compositions of the planets that form in it. We use the Molecules with ALMA at Planet-forming Scales (MAPS) data to constrain the elemental composition of the gas at the locations of potentially forming planets. The elemental abundances are inferred by comparing source-specific gas-grain thermochemical models with variable C/O ratios and small-grain abundances from the DALI code with CO and C2H column densities derived from the high-resolution observations of the disks of AS 209, HD 163296, and MWC 480. Elevated C/O ratios (~2.0), even within the CO ice line, are necessary to match the inferred C2H column densities over most of the pebble disk. Combined with constraints on the CO abundances in these systems, this implies that both the O/H and C/H ratios in the gas are substellar by a factor of 4-10, with the O/H depleted by a factor of 20-50, resulting in the high C/O ratios. This necessitates that even within the CO ice line, most of the volatile carbon and oxygen is still trapped on grains in the midplane. Planets accreting gas in the gaps of the AS 209, HD 163296, and MWC 480 disks will thus acquire very little carbon and oxygen after reaching the pebble isolation mass. In the absence of atmosphere-enriching events, these planets would thus have a strongly substellar O/H and C/H and superstellar C/O atmospheric composition. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.

Dates and versions

insu-03672374 , version 1 (19-05-2022)

Identifiers

Cite

Arthur D. Bosman, Felipe Alarcón, Edwin A. Bergin, Ke Zhang, Merel L. R. Van'T Hoff, et al.. Molecules with ALMA at Planet-forming Scales (MAPS). VII. Substellar O/H and C/H and Superstellar C/O in Planet-feeding Gas. The Astrophysical Journal Supplement Series, 2021, 257, ⟨10.3847/1538-4365/ac1435⟩. ⟨insu-03672374⟩
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