NASA’s Picture of the Day: A dark nebula forms as a veil meets a faint glow in the Ophiuchus constellation

A Dark Veil in Ophiuchus (Image: NASA)

The night sky never runs out of wonders. Astronomers have now turned their attention to a faint hydrogen-alpha glow. It belongs to the vast emission region known as Sh2-27 in the constellation Ophiuchus.

What is Sh2-27, and why is it important?
The glowing region covers nearly three degrees of sky. It lies in the nebula-rich direction of the central Milky Way. At its heart is the hot O-type star Zeta Ophiuchi. This runaway star is driving the formation of the large HII region.

What about the dark dust clouds nearby?
Alongside the glowing gas, dark wisps are seen. These interstellar dust clouds are labelled as LDN 234 and LDN 204. Both were listed in the 1962 Lynds Catalogue of Dark Nebulae. American astronomer Beverly Lynds first identified these obscuring clouds.

Sh2-27, Zeta Oph, and the dark nebulae sit about 500 light-years away. That is relatively close in cosmic terms. At this distance, the telescope frame spans nearly 25 light-years across.