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Webb Captures Top of Iconic Horsehead Nebula in Unprecedented Detail

A clumpy dome of blueish-gray clouds rises about a third of the way from the bottom. Above it, streaky, translucent red wisps brush upward to about halfway up the image. The top half of the image is the black background of space with one prominent, bright white star with Webb’s 8-point diffraction spikes. Additional stars and galaxies are scattered throughout the image, although very few are seen through the thick clouds at bottom and all are significantly smaller than the largest star.

This image of the Horsehead Nebula from NASA’s James Webb Space Telescope focuses on a portion of the horse’s “mane”.

Credits: NASA, ESA, CSA, K. Misselt (University of Arizona) and A. Abergel (IAS/University Paris-Saclay, CNRS)

NASA’s James Webb Space Telescope has captured the sharpest infrared images to date of a zoomed-in portion of one of the most distinctive objects in our skies, 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 region’s complexity with unprecedented spatial resolution.

Image: Horsehead Nebula (NIRCam)

This image of the Horsehead Nebula from NASA’s James Webb Space Telescope focuses on a portion of the horse’s “mane” that is about 0.8 light-years in width. It was taken with Webb’s NIRCam (Near-infrared Camera). The ethereal clouds that appear blue at the bottom of the image are dominated by cold, molecular hydrogen. Red-colored wisps extending above the main nebula represent mainly atomic hydrogen gas. In this area, known as a photodissociation region, ultraviolet light from nearby young, massive stars creates a mostly neutral, warm area of gas and dust between the fully ionized gas above and the colder nebula below. As with many Webb images, distant galaxies are sprinkled in the background. This image is composed of light at wavelengths of 1.4 and 2.5 microns (represented in blue), 3.0 and 3.23 microns (cyan), 3.35 microns (green), 4.3 microns (yellow), and 4.7 and 4.05 microns (red).

NASA, ESA, CSA, K. Misselt (University of Arizona) and A. Abergel (IAS/University Paris-Saclay, CNRS)

Webb’s new images show part of the sky in the constellation Orion (The Hunter), in the western side of a dense region known as the Orion B molecular cloud. Rising from turbulent waves of dust and gas is the Horsehead Nebula, otherwise known as Barnard 33, which resides roughly 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 surrounding the Horsehead have already dissipated, but the jutting pillar is made of thick clumps of material and therefore is harder 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 area of gas and dust between the fully ionized gas surrounding the massive stars and the clouds in which they are born. This UV radiation strongly influences the chemistry of these regions and acts as a significant source of heat.

Image: Horsehead Nebula (MIRI)

The image is more than half-filled from the bottom up by a small section of the Horsehead Nebula. Streaky clouds of white, gray and blue resemble a foamy wave crashing at the seashore. The nebula stops at a textured, fuzzy-looking edge that follows a slight curve. Above it a small number of distant stars and galaxies lie on a dark but multi-colored background.

This image of the Horsehead Nebula from NASA’s James Webb Space Telescope focuses on a portion of the horse’s “mane.” It was taken with Webb’s MIRI (Mid-Infrared Instrument). Mid-infrared light captures the glow of substances like dusty silicates and soot-like molecules called polycyclic aromatic hydrocarbons. In this image, blue represents light at wavelengths of 5.6, 7.7, and 10 microns; green is 11, 12, and 15 microns; and red is 18, 21, and 25 microns.

NASA, ESA, CSA, K. Misselt (University of Arizona) and A. Abergel (IAS/University Paris-Saclay, CNRS)

These regions occur where interstellar gas is dense enough to remain mostly neutral, but not dense enough to prevent the penetration of UV light from massive stars. The light emitted from such PDRs provides a unique tool to study the physical and chemical processes that drive the evolution of interstellar matter in our galaxy, and throughout the universe from the early era of vigorous star formation to the present day.

Due to its proximity and its nearly 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 regions in the sky to study how radiation interacts with interstellar matter.

Image: Horsehead Nebula (Euclid, Hubble and Webb Images)

A horizontal collage of three images of the Horsehead Nebula. The left image is labeled “Euclid (Visible-Infrared)” and shows a dusty red-brown nebula at bottom with wispy blue clouds in the middle and the black background of space at top, with stars throughout. A portion of the nebula shaped like the head of a seahorse juts upward from the thickest part of the nebula into the blue wisps. A small box around it connects to the second image labeled “Hubble (Infrared)”, where the Nebula is zoomed in on. Here the central part of the horse’s head remains a dark, dusty red, while the outer portions become a translucent, ethereal gray. At the top of the horse’s head, a box connects to the third image labeled “Webb (Infrared)”. A clumpy dome of blueish-gray clouds rises about a third of the way into the image, capped with translucent red wisps and, at top, a single, prominent star.

This image showcases three views of one of the most distinctive objects in our skies, the Horsehead Nebula. The first image (left), released in November 2023, features the Horsehead Nebula as seen in visible light by ESA’s Euclid telescope, which has contributions from NASA. The second image (middle) shows a view of the Horsehead Nebula in near-infrared light from NASA's Hubble Space Telescope, which was featured as the telescope’s 23rd anniversary image in 2013. This image reveals a beautiful, delicate structure that is normally obscured by dust. The third image (right) features a new view of the Horsehead Nebula from NASA's James Webb Space Telescope’s NIRCam (Near-Infrared Camera) instrument.

ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, NASA, ESA, and the Hubble Heritage Team (AURA/STScI), ESA/Webb, CSA, K. Misselt (University of Arizona), M. Zamani (ESA/Webb)

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 Horsehead. As UV light evaporates the dust cloud, dust particles are swept out away from the cloud, carried with the heated gas. Webb has detected a network of thin features tracing this movement. The observations have also allowed astronomers to investigate how the dust blocks and emits light, and to better understand the multidimensional shape of the nebula.

Next, astronomers intend to study the spectroscopic data that has been obtained to gain insights into the evolution of the physical and chemical properties of the material observed across the nebula.

These observations were taken in the Webb GTO program 1192, and the results were published today in Astronomy & Astrophysics.

The James Webb Space Telescope is the world's premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing 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.

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The research results can be viewed in the Astronomy & Astrophysics Journal.