The Wisconsin H-Alpha Mapper Northern Sky Survey of Galactic Ionized Hydrogen

TL;DR

The WHAM northern sky survey provides high-resolution, velocity-resolved H-alpha emission maps of the Galaxy, enabling detailed comparison of ionized and neutral interstellar medium components on a global scale.

Contribution

This survey offers the first comprehensive, velocity-resolved H-alpha maps of the northern sky at unprecedented sensitivity and resolution.

Findings

Detection of Galactic features as faint as 0.1 Rayleighs

All-sky maps reveal complex kinematic structures

Data availability for further research

Abstract

The Wisconsin H-Alpha Mapper (WHAM) has completed a one-degree resolution, velocity-resolved northern sky survey of H-alpha emission from our Galaxy. The unprecedented sensitivity of the instrument and accurate spectral subtraction of atmospheric features allow us to detect Galactic features as faint as 0.1 Rayleighs (EM ~ 0.25 cm^{-6} pc). This survey allows a direct comparison of the ionized and neutral components of the ISM on a global scale for the first time. All-sky maps of H-alpha emission in select velocity bands highlight the rich kinematic structure of the Galaxy's ionized gas. The full set of data from the WHAM survey is now available at http://www.astro.wisc.edu/wham/. (abridged)