The Distance to High-Velocity Cloud Complex M

TL;DR

This study uses high-resolution 21-cm survey data to analyze the structure and distance of high-velocity cloud Complex M, revealing its physical interaction with an arched filament and estimating its mass and energy, consistent with a supernova origin.

Contribution

The paper determines the distance to Complex M using HI data and links its structure to a larger filament, providing new insights into its physical properties and origin.

Findings

Complex M is associated with a long arched filament.

The distance to Complex M is estimated at 150 pc.

The total energy of the cloud is consistent with a supernova explosion.

Abstract

21-cm HI4PI survey data are used to study the anomalous-velocity hydrogen gas associated with high-velocity cloud Complex M. These high-sensitivity, high-resolution, high-dynamic-range data show that many of the individual features, including MI, MIIa, and MIIb, are components of a long, arched filament that extends from about (l, b) = (105{\deg}, 53{\deg}) to (l, b) = (196{\deg}, 55{\deg}). Maps at different velocities, results from Gaussian analysis, and observations of associated high-energy emission make a compelling case that the MI cloud and the arched filament are physically interacting. If this is the case, we can use the distance to MI, 150 pc as reported by Schmelz & Verschuur (2022), to set the distance to Complex M. The estimated mass of Complex M is then about 120 solar masses and the energy implied using the observed line-of-sight velocity, -85 km/s, is 8.4 x 10^48 ergs. Integrating over 4{\pi} steradians, the total energy for a spherically symmetrical explosion is estimated to be 1.9 x 10^50 ergs, well within the energy budget of a typical supernova.