An Interaction of a Magellanic Leading Arm High Velocity Cloud with the Milky Way Disk

TL;DR

This study presents evidence of an interaction between a Magellanic Leading Arm high velocity cloud and the Milky Way disk, providing insights into their dynamics and spatial relationship.

Contribution

It offers the first detailed analysis of a Leading Arm cloud interacting with the Galactic disk, including a kinematic distance estimate.

Findings

Interaction occurs at velocities compatible with Galactic rotation

Kinematic distance to the cloud is approximately 21 kpc

The Leading Arm crosses the Galactic plane at about 17 kpc radius

Abstract

The Leading Arm of the Magellanic System is a tidally formed HI feature extending $\sim 60\arcdeg$ from the Magellanic Clouds ahead of their direction of motion. Using atomic hydrogen (HI) data from the Galactic All Sky-Survey (GASS), supplemented with data from the Australia Telescope Compact Array, we have found evidence for an interaction between a cloud in the Leading Arm and the Galactic disk where the Leading Arm crosses the Galactic plane. The interaction occurs at velocities permitted by Galactic rotation, which allows us to derive a kinematic distance to the cloud of 21 kpc, suggesting that the Leading Arm crosses the Galactic Plane at a Galactic radius of $R\approx 17$ kpc.