Molecules with ALMA at Planet-forming Scales (MAPS). X. Studying deuteration at high angular resolution toward protoplanetary disks
Abstract
Deuterium fractionation is dependent on various physical and chemical parameters. Thus, the formation location and thermal history of material in the solar system is often studied by measuring its D/H ratio. This requires knowledge about the deuteration processes operating during the planet formation era. We aim to study these processes by radially resolving the DCN/HCN (at 0″3 resolution) and N2D+/N2H+ (~0″3-0″9) column density ratios toward the five protoplanetary disks observed by the Molecules with ALMA at Planet-forming scales (MAPS) Large Program. DCN is detected in all five sources, with one newly reported detection. N2D+ is detected in four sources, two of which are newly reported detections. We derive column density profiles that allow us to study the spatial variation of the DCN/HCN and N2D+/N2H+ ratios at high resolution. DCN/HCN varies considerably for different parts of the disks, ranging from 10-3 to 10-1. In particular, the inner-disk regions generally show significantly lower HCN deuteration compared with the outer disk. In addition, our analysis confirms that two deuterium fractionation channels are active, which can alter the D/H ratio within the pool of organic molecules. N2D+ is found in the cold outer regions beyond ~50 au, with N2D+/N2H+ ranging between 10-2 and 1 across the disk sample. This is consistent with the theoretical expectation that N2H+ deuteration proceeds via the low-temperature channel only. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
Citation
Cataldi , G , Yamato , Y , Aikawa , Y , Bergner , J B , Furuya , K , Guzmán , V V , Huang , J , Loomis , R A , Qi , C , Andrews , S M , Bergin , E A , Booth , A S , Bosman , A D , Cleeves , L I , Czekala , I , Ilee , J D , Law , C J , Le Gal , R , Liu , Y , Long , F , Ménard , F , Nomura , H , Öberg , K I , Schwarz , K R , Teague , R , Tsukagoshi , T , Walsh , C , Wilner , D J & Zhang , K 2021 , ' Molecules with ALMA at Planet-forming Scales (MAPS). X. Studying deuteration at high angular resolution toward protoplanetary disks ' , Astrophysical Journal Supplement Series , vol. 257 , no. 1 , 10 . https://doi.org/10.3847/1538-4365/ac143d
Publication
Astrophysical Journal Supplement Series
Status
Peer reviewed
ISSN
0067-0049Type
Journal article
Description
Funding: J.B.B., J.H., I.C., K.R.S., and K.Z. acknowledge the support of NASA through Hubble Fellowship grants HST-HF2-51429.001-A, HST-HF2-51460.001-A, HST-HF2-51405.001-A, HST-HF2-51419.001, and HST-HF2-51401.001, 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. A.S.B. acknowledges the studentship funded by the Science and Technology Facilities Council of the United Kingdom (STFC). J.D.I. acknowledges support from STFC under ST/T000287/1. C.W. acknowledges financial support from the University of Leeds, STFC, and UKRI (grant Nos. ST/R000549/1, ST/T000287/1, MR/T040726/1).Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.