NASA’s James Webb Space Telescope has captured the sharpest infrared images yet of a zoomed-in portion of one of the most striking objects in our sky, the Horsehead Nebula. These observations show the top of the ‘horse’s mane’ or edge of this iconic nebula in a whole new light, capturing the complexity of the region with unprecedented spatial resolution.
Webb’s new images show part of the sky in the constellation Orion (Hunter), at the western end of a dense region known as the Orion B molecular cloud. Rising from turbulent waves of dust and gas is the Horsehead Nebula, also also known as Barnard 33, which is located approximately 1,300 light years away.
The nebula formed from a collapsing interstellar cloud of material and glows because it is illuminated by a nearby hot star. The gas clouds around the Horse Head have already disappeared, but the protruding pillar is made of thick clumps of material and is therefore more difficult to erode. Astronomers estimate that the Horsehead has about five million years left before it too disintegrates. Webb’s new view focuses on the illuminated edge of the top of the nebula’s distinctive dust and gas structure.
The Horsehead Nebula is a well-known photodissociation region, or PDR. In such a region, ultraviolet (UV) light from young, massive stars creates a mostly neutral, warm region of gas and dust between the fully ionized gas surrounding the massive stars and the clouds in which they were born. This UV radiation has a strong influence on the chemistry of these areas and acts as an important heat source.
These regions occur where interstellar gas is dense enough to remain largely neutral, but not dense enough to prevent the penetration of UV light from massive stars. The light emitted by such PDRs provides a unique tool to study the physical and chemical processes driving the evolution of interstellar matter in our Galaxy and the entire universe, from the early era of vigorous star formation to the present day.
Due to its proximity and almost edge-on geometry, the Horsehead Nebula is an ideal target for astronomers to study the physical structures of PDRs and the molecular evolution of the gas and dust within their respective environments, and the transition regions between them. It is considered one of the best areas of the sky to study how radiation interacts with interstellar matter.
Thanks to Webb’s MIRI and NIRCam instruments, an international team of astronomers has revealed for the first time the small-scale structures of the illuminated edge of the Horse’s Head. As UV light evaporates the dust cloud, dust particles are swept away from the cloud and carried along with the heated gas. Webb has detected a network of sparse features that track this movement. The observations have also allowed astronomers to investigate how the dust blocks and emits light and better understand the nebula’s multi-dimensional shape.
Next, astronomers plan to study the spectroscopic data obtained to understand the evolution of the physical and chemical properties of the material observed in the nebula.
These observations were made for the Webb GTO program 1192 and the results were published today in Astronomy & Astrophysics.
The James Webb Space Telescope is the world’s premier observatory for space science. Webb solves mysteries in our solar system, looks beyond to distant worlds around other stars and investigates the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners ESA (European Space Agency) and the Canadian Space Agency.