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

We perform imaging and analyses of SMA 1.3 mm continuum, C18O (2-1) and 12CO(2-1) line data of 17 Class 0 and 0/I protostars to study their gas kinematicson a 1,000-AU scale. Continuum and C18O (2-1) emission are detected toward allthe sample sources and show central primary components with sizes of ~600-1,500AU associated with protostars. The velocity gradients in C18O (2-1) have wideranges of orientations from parallel to perpendicular to the outflows, withmagnitudes from ~1 to ~530 km/s/pc. We construct a simple kinematic model toreproduce the observed velocity gradients, estimate the infalling androtational velocities, and infer the disk radii and the protostellar masses.The inferred disk radii range from <5 AU to >500 AU with estimated protostellarmasses from <0.1 Msun to >1 Msun. Our results hint that both large and smalldisks are possibly present around Class 0 protostars, which could be a sign ofdisk growth at the Class 0 stage. In addition, the directions of the overallvelocity gradients in 7 out of the 17 sources are close to perpendicular totheir outflow axes, which is a signature of significant rotational motions.From our model fitting, the specific angular momenta in these sources areestimated to be >2E-4 km/s*pc, suggesting that magnetic braking is unlikelyefficient on a 1,000-AU scale in these Class 0 and 0/I sources. In a sub-samplewith observed magnetic field orientations, we find no source with largespecific angular momenta together with closely aligned magnetic field andoutflow axes. This possibly hints that the magnetic field, if originallyaligned with the rotational axis, can play a role in removing angular momentumfrom infalling material at the Class 0 stage. We discuss our results incomparison with theoretical models of collapsing dense cores with and withoutmagnetic fields in the context of disk formation.

astrophysical journal/the astrophysical journal

Observations of Infalling and Rotational Motions on a 1,000-AU Scale  around 17 Class 0 and 0/I Protostars: Hints of Disk Growth and Magnetic  Braking?