English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

H2CO is one of the most readily detected organic molecules in protoplanetarydisks. Yet its distribution and dominant formation pathway(s) remain largelyunconstrained. To address these issues, we present ALMA observations of twoH2CO lines (3_{12}-2_{11} and 5_{15}-4_{14}) at 0".5 (~30 au) spatialresolution toward the disk around the nearby T Tauri star TW Hya. Emission fromboth lines is spatially resolved, showing a central depression, a peak at 0".4radius, and a radial decline at larger radii with a bump at ~1", near themillimeter continuum edge. We adopt a physical model for the disk and use toymodels to explore the radial and vertical H2CO abundance structure. We findthat the observed emission implies the presence of at least two distinct H2COgas reservoirs: (1) a warm and unresolved inner component (<10 au), and (2) anouter component that extends from ~15 au to beyond the millimeter continuumedge. The outer component is further constrained by the line ratio to arise ina more elevated disk layer at larger radii. The inferred H2CO abundancestructure agrees well with disk chemistry models, which predict efficient H2COgas-phase formation close to the star, and cold H2CO grain surface formation,through H additions to condensed CO, followed by non-thermal desorption in theouter disk. The implied presence of active grain surface chemistry in the TWHya disk is consistent with the recent detection of CH3OH emission, andsuggests that more complex organic molecules are formed in disks, as well.

H2CO distribution and formation in the TW Hya disk