GREAT spectrum from star forming region

GREAT spectrum from star forming region
Optical colour image of the Rho Ophiuchi star forming region, about 400 light years from Earth, with dark filamentary dust clouds. The position of the optically invisible low-mass protostar IRAS16293-2422 around which interstellar deuterated hydroxyl OD has been detected is marked with a red circle. The absorption line spectrum, observed with GREAT on board SOFIA, displays the molecule’s fingerprint at 1.3915 terahertz (or 215 microns wavelength).
The inset shows the OD molecule (red: oxygen, grey: deuterium), an isotopic substitute of hydroxyl (OH) in which the hydrogen atom is replaced by the heavier deuterium. This deuterated molecule is an important marker in the formation of interstellar water and may serve as a chemical clock in the early star formation process.
The bright yellowish star at the bottom left is Antares, one of the brightest stars in the sky. Below and to Antares’ right is the globular cluster Messier 4.

Background: ESO/S. Guisard. Spectrum: MPIfR/B. Parise.