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

Turbulence can transport angular momentum in protoplanetary disks andinfluence the growth and evolution of planets. With spatially and spectrallyresolved molecular emission line measurements provided by (sub)millimeterinterferometric observations, it is possible to directly measure non-thermalmotions in the disk gas that can be attributed to this turbulence. We report anew constraint on the turbulence in the disk around HD 163296, a nearby young Astar, determined from ALMA Science Verification observations of four COemission lines (the CO(3-2), CO(2-1), 13CO(2-1), and C18O(2-1) transitions).The different optical depths for these lines permit probes of non-thermalline-widths at a range of physical conditions (temperature and density) anddepths into the disk interior. We derive stringent limits on the non-thermalmotions in the upper layers of the outer disk such that any contribution to theline-widths from turbulence is <3% of the local sound speed. These limits areapproximately an order of magnitude lower than theoretical predictions forfull-blown MHD turbulence driven by the magneto-rotational instability,potentially suggesting that this mechanism is less efficient in the outer(R>30AU) disk than has been previously considered.

Weak Turbulence in the HD 163296 Protoplanetary Disk Revealed by ALMA CO Observations