# Vertical Structure of the Transition Zone from Infalling Rotating Envelope to Disk in the Class 0 Protostar, IRAS04368+2557

## TL;DR

This study uses high-resolution ALMA observations to resolve the detailed radial and vertical structure of the envelope and disk in a Class 0 protostar, revealing the dynamics around the centrifugal barrier and implications for outflow launching.

## Contribution

First detailed imaging of the vertical structure of a Class 0 protostar's envelope and disk, linking the centrifugal barrier to outflow mechanisms.

## Key findings

- The dust continuum shows a flared disk-like structure.
- The envelope thickness increases inward, near the centrifugal radius.
- SO emission suggests deceleration and possible angular momentum extraction at the centrifugal barrier.

## Abstract

We have resolved for the first time the radial and vertical structure of the almost edge-on envelope/disk system of the low-mass Class 0 protostar L1527. For that, we have used ALMA observations with a spatial resolution of 0.25$^{\prime\prime}$$\times$0.13$^{\prime\prime}$ and 0.37$^{\prime\prime}$$\times$0.23$^{\prime\prime}$ at 0.8 mm and 1.2 mm, respectively. The L1527 dust continuum emission has a deconvolved size of 78 au $\times$ 21 au, and shows a flared disk-like structure. A thin infalling-rotating envelope is seen in the CCH emission outward of about 150 au, and its thickness is increased by a factor of 2 inward of it. This radius lies between the centrifugal radius (200 au) and the centrifugal barrier of the infalling-rotating envelope (100 au). The gas stagnates in front of the centrifugal barrier and moves toward vertical directions. SO emission is concentrated around and inside the centrifugal barrier. The rotation speed of the SO emitting gas is found to be decelerated around the centrifugal barrier. A part of the angular momentum could be extracted by the gas which moves away from the mid-plane around the centrifugal barrier. If this is the case, the centrifugal barrier would be related to the launching mechanism of low velocity outflows, such as disk winds.