Molecules with ALMA at Planet-forming Scales (MAPS). XI. CN and HCN as Tracers of Photochemistry in Disks

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dc.contributor.authorBergner, Jennifer B.
dc.contributor.authorOberg, Karin I.
dc.contributor.authorGuzman, Viviana V.
dc.contributor.authorLaw, Charles J.
dc.contributor.authorLoomis, Ryan A.
dc.contributor.authorCataldi, Gianni
dc.contributor.authorBosman, Arthur D.
dc.contributor.authorAikawa, Yuri
dc.contributor.authorAndrews, Sean M.
dc.contributor.authorBergin, Edwin A.
dc.contributor.authorBooth, Alice S.
dc.contributor.authorCleeves, L. Ilsedore
dc.contributor.authorCzekala, Ian
dc.contributor.authorHuang, Jane
dc.contributor.authorIlee, John D.
dc.contributor.authorLe Gal, Romane
dc.contributor.authorLong, Feng
dc.contributor.authorNomura, Hideko
dc.contributor.authorMenard, Francois
dc.contributor.authorQi, Chunhua
dc.contributor.authorSchwarz, Kamber R.
dc.contributor.authorTeague, Richard
dc.contributor.authorTsukagoshi, Takashi
dc.contributor.authorWalsh, Catherine
dc.contributor.authorWilner, David J.
dc.contributor.authorYamato, Yoshihide
dc.date.accessioned2025-01-20T22:05:22Z
dc.date.available2025-01-20T22:05:22Z
dc.date.issued2021
dc.description.abstractUV photochemistry in the surface layers of protoplanetary disks dramatically alters their composition relative to previous stages of star formation. The abundance ratio CN/HCN has long been proposed to trace the UV field in various astrophysical objects; however, to date the relationship between CN, HCN, and the UV field in disks remains ambiguous. As part of the ALMA Large Program MAPS (Molecules with ALMA at Planet-forming Scales), we present observations of CN N = 1-0 transitions at 0.'' 3 resolution toward five disk systems. All disks show bright CN emission within similar to 50-150 au, along with a diffuse emission shelf extending up to 600 au. In all sources we find that the CN/HCN column density ratio increases with disk radius from about unity to 100, likely tracing increased UV penetration that enhances selective HCN photodissociation in the outer disk. Additionally, multiple millimeter dust gaps and rings coincide with peaks and troughs, respectively, in the CN/HCN ratio, implying that some millimeter substructures are accompanied by changes to the UV penetration in more elevated disk layers. That the CN/HCN ratio is generally high (>1) points to a robust photochemistry shaping disk chemical compositions and also means that CN is the dominant carrier of the prebiotically interesting nitrile group at most disk radii. We also find that the local column densities of CN and HCN are positively correlated despite emitting from vertically stratified disk regions, indicating that different disk layers are chemically linked. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
dc.fuente.origenWOS
dc.identifier.doi10.3847/1538-4365/ac143a
dc.identifier.eissn1538-4365
dc.identifier.issn0067-0049
dc.identifier.urihttps://doi.org/10.3847/1538-4365/ac143a
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/94140
dc.identifier.wosidWOS:000714210000001
dc.issue.numero1
dc.language.isoen
dc.revistaAstrophysical journal supplement series
dc.rightsacceso restringido
dc.titleMolecules with ALMA at Planet-forming Scales (MAPS). XI. CN and HCN as Tracers of Photochemistry in Disks
dc.typeartículo
dc.volumen257
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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