JWST captures zooms in on the ‘mane’ of the iconic Horsehead Nebula

This image of the Horsehead Nebula from the 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). Image: NASA, ESA, CSA, Karl Misselt (University of Arizona), Alain Abergel (IAS, CNRS).

The James Webb Space Telescope (JWST) 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. The 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.

The 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.

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 the Euclid telescope. The second image (middle) shows a view of the Horsehead Nebula in near-infrared light from the Hubble Space Telescope, which was featured as the telescope’s 23rd anniversary image in 2013. The third image (right) features the new view of the Horsehead Nebula from JWST. Image: NASA, ESA, CSA, Karl Misselt (University of Arizona), Alain Abergel (IAS, CNRS), Mahdi Zamani The Euclid Consortium, Hubble Heritage Project (STScI, AURA).

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.

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.

This image of the Horsehead Nebula’s “mane” 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. Image: NASA, ESA, CSA, Karl Misselt (University of Arizona), Alain Abergel (IAS, CNRS).

Thanks to JWST’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 have 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 for the JWST GTO program 1192 and the results were published 29 April 2024 in Astronomy & Astrophysics.

Source: Space Telescope Science Institute news release.