Detection of deuterium Balmer lines in the Orion Nebula

TL;DR

This paper reports the first detection of deuterium Balmer lines in the Orion Nebula, revealing narrow emission features with specific velocity shifts, likely excited by UV fluorescence at the interface of the nebula and molecular cloud.

Contribution

First identification of deuterium Balmer emission lines in the Orion Nebula using high-resolution spectroscopy.

Findings

Deuterium Balmer lines are very narrow with 11 km/s velocity shifts.

Lines are likely excited by UV fluorescence from Lyman lines.

Lines originate from the interface between HII region and molecular cloud.

Abstract

The detection and first identification of the deuterium Balmer emission lines, D-alpha and D-beta, in the core of the Orion Nebula is reported. Observations were conducted at the 3.6m Canada-France-Hawaii Telescope, using the Echelle spectrograph Gecko. These lines are very narrow and have identical 11 km/s velocity shifts with respect to H-alpha and H-beta. They are probably excited by UV continuum fluorescence from the Lyman (DI) lines and arise from the interface between the HII region and the molecular cloud.