Orion’s Veil Comes Out of Its Shell

by Anashe Bandari

Orion’s Veil might be breaking.

Within the Orion Nebula is a massive set of stars known as the Trapezium stars. The winds from the Trapezium stars blow a bubble of dust and gas in the area in front of them, called Orion’s Veil. The majority of Orion’s Veil is sparse, with most of its gas lying in the bubble’s wall. The wall, or Orion’s Veil shell, is about a light-year thick and expanding toward us – and recent observations by the Stratospheric Observatory for Infrared Astronomy (SOFIA) German REceiver for Astronomy at Terahertz Frequencies (GREAT) have identified some unexpected features in it.

A 3D model of the Orion Nebula shows Orion’s Veil shell as a bluish gas surrounding the nebula depicted in red and yellow
A 3D model of the Orion Nebula shows Orion’s Veil shell as a bluish gas surrounding the nebula depicted in red and yellow. Researchers using SOFIA found a protrusion in the shell, which could allow gas and dust to escape beyond the shell. Credit: NASA, ESA, Frank Summers (STScI), Greg T. Bacon (STScI), Lisa Frattare (STScI), Zolt G. Levay (STScI), K. Litaker (STScI). Acknowledgment: Axel Mellinger, Robert Gendler, Rogelio B. Andreo

“The bubble – with a diameter of approximately seven light-years – should be an almost sphere-like structure, but we found a protrusion in its northwestern part,” said Ümit Kavak, a postdoctoral researcher at SOFIA based out of NASA’s Ames Research Center in California’s Silicon Valley, who is the lead author on a recent paper describing the studies.

The SOFIA observations show ionized carbon emission in this protrusion, which Kavak used to determine its size, structure, and how it is expanding, in hopes of uncovering its origins and future.

Shaped like a “U” lying on its side, the protrusion extends well beyond Orion’s Veil shell. It is a likely spot for the shell to pierce, and the protrusion’s chimney-like top seems to imply it already has.

Infrared image of Orion Nebula with curved and dashed lines over it showing outflows, rims, lobes, shells, and protrusion along with location of Trapezium stars.
Schematic picture of the protrusion (green lines, center right) and outflows of ionized carbon extending beyond the protrusion — where the shell has likely been pierced — overlaid on a Wide-field Infrared Survey Explorer image of the region. Credit: NASA/JPL-Caltech/WISE Team; Kavak et al.

“When you breach the Veil shell, you effectively start stirring a cosmic soup of gas and dust by adding turbulence,” Kavak said.

“This isn’t the most appetizing soup, but it’s one of the ways to form new stars or limit future star formation,” added Alexander Tielens, a researcher at Leiden University and another author on the paper.

This turbulence affects the density, temperature, and chemistry of its surrounding region, which may ultimately lead to the creation or destruction of star formation sites.

The group also identified a second, weaker protrusion, which they plan to investigate further in a future publication. Together, these protrusions affect the entire morphology of the Orion Nebula.

SOFIA is a joint project of NASA and the German Space Agency at DLR. DLR provides the telescope, scheduled aircraft maintenance, and other support for the mission. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science, and mission operations in cooperation with the Universities Space Research Association, headquartered in Columbia, Maryland, and the German SOFIA Institute at the University of Stuttgart. The aircraft is maintained and operated by NASA’s Armstrong Flight Research Center Building 703, in Palmdale, California. SOFIA achieved full operational capability in 2014, and the mission will conclude no later than Sept. 30, 2022. SOFIA will continue its regular operations until then, including science flights and a deployment to New Zealand this summer.