TY - JOUR
T1 - Molecules with ALMA at Planet-forming Scales (MAPS). IV. Emission surfaces and vertical distribution of molecules
AU - Law, Charles J.
AU - Teague, Richard
AU - Loomis, Ryan A.
AU - Bae, Jaehan
AU - Öberg, Karin I.
AU - Czekala, Ian
AU - Andrews, Sean M.
AU - Aikawa, Yuri
AU - Alarcón, Felipe
AU - Bergin, Edwin A.
AU - Bergner, Jennifer B.
AU - Booth, Alice S.
AU - Bosman, Arthur D.
AU - Calahan, Jenny K.
AU - Cataldi, Gianni
AU - Cleeves, L. Ilsedore
AU - Furuya, Kenji
AU - Guzmán, Viviana V.
AU - Huang, Jane
AU - Ilee, John D.
AU - Le Gal, Romane
AU - Liu, Yao
AU - Long, Feng
AU - Ménard, François
AU - Nomura, Hideko
AU - Pérez, Laura M.
AU - Qi, Chunhua
AU - Schwarz, Kamber R.
AU - Soto, Daniela
AU - Tsukagoshi, Takashi
AU - Yamato, Yoshihide
AU - van't Hoff, Merel L. R.
AU - Walsh, Catherine
AU - Wilner, David J.
AU - Zhang, Ke
N1 - Funding: I.C. was supported by NASA through the NASA Hubble Fellowship grant HST-HF2-51405.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555.
C.W. acknowledges financial support from the University of Leeds, STFC, and UKRI (grant Nos. ST/R000549/1, ST/T000287/1, MR/T040726/1).
PY - 2021/11
Y1 - 2021/11
N2 - The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a unique opportunity to study the vertical distribution of gas, chemistry, and temperature in the protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. By using the asymmetry of molecular line emission relative to the disk major axis, we infer the emission height (z) above the midplane as a function of radius (r). Using this method, we measure emitting surfaces for a suite of CO isotopologues, HCN, and C2H. We find that 12CO emission traces the most elevated regions with z/r ∼< 0.3 , while emission from the less abundant 13CO and C18O probes deeper into the disk at altitudes of z/r ~< 0.2 . C2H and HCN have lower opacities and signal-to-noise ratios, making surface fitting more difficult, and could only be reliably constrained in AS 209, HD 163296, and MWC 480, with z/r ~< 0.1 , i.e., relatively close to the planet-forming midplanes. We determine peak brightness temperatures of the optically thick CO isotopologues and use these to trace 2D disk temperature structures. Several CO temperature profiles and emission surfaces show dips in temperature or vertical height, some of which are associated with gaps and rings in line and/or continuum emission. These substructures may be due to local changes in CO column density, gas surface density, or gas temperatures, and detailed thermochemical models are necessary to better constrain their origins and relate the chemical compositions of elevated disk layers with those of planet-forming material in disk midplanes. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
AB - The Molecules with ALMA at Planet-forming Scales (MAPS) Large Program provides a unique opportunity to study the vertical distribution of gas, chemistry, and temperature in the protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480. By using the asymmetry of molecular line emission relative to the disk major axis, we infer the emission height (z) above the midplane as a function of radius (r). Using this method, we measure emitting surfaces for a suite of CO isotopologues, HCN, and C2H. We find that 12CO emission traces the most elevated regions with z/r ∼< 0.3 , while emission from the less abundant 13CO and C18O probes deeper into the disk at altitudes of z/r ~< 0.2 . C2H and HCN have lower opacities and signal-to-noise ratios, making surface fitting more difficult, and could only be reliably constrained in AS 209, HD 163296, and MWC 480, with z/r ~< 0.1 , i.e., relatively close to the planet-forming midplanes. We determine peak brightness temperatures of the optically thick CO isotopologues and use these to trace 2D disk temperature structures. Several CO temperature profiles and emission surfaces show dips in temperature or vertical height, some of which are associated with gaps and rings in line and/or continuum emission. These substructures may be due to local changes in CO column density, gas surface density, or gas temperatures, and detailed thermochemical models are necessary to better constrain their origins and relate the chemical compositions of elevated disk layers with those of planet-forming material in disk midplanes. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
KW - Protoplanetary disks
KW - Interstellar molecules
KW - Astrochemistry
KW - High angular resolution
KW - Circumstellar disks
KW - Planet formation
U2 - 10.3847/1538-4365/ac1439
DO - 10.3847/1538-4365/ac1439
M3 - Article
SN - 0067-0049
VL - 257
JO - Astrophysical Journal Supplement Series
JF - Astrophysical Journal Supplement Series
IS - 1
M1 - 4
ER -