The Horsehead Nebula lies in the constellation Orion, about 1300 light-years away, and is a popular target for amateur and professional astronomers alike. It sits just to the south of star Alnitak, the easternmost of Orion’s famous three-star belt, and is part of the vast Orion Molecular Cloud complex.
The new far-infrared Herschel view shows in spectacular detail the scene playing out around the Horsehead Nebula at the right-hand side of the image, where it seems to surf like a ‘white horse’ in the waves of turbulent star-forming clouds.
It appears to be riding towards another favourite stopping point for astrophotographers: NGC 2024, also known as the Flame Nebula. This star-forming region appears obscured by dark dust lanes in visible light images, but blazes in full glory in the far-infrared Herschel view.
Intense radiation streaming away from newborn stars heats up the surrounding dust and gas, making it shine brightly to Herschel’s infrared-sensitive eyes.
The panoramic view also covers two prominent sites of massive star formation to the northeast (left-hand side of this image), known as NGC 2068 (or M78) and NGC 2071. These take on the appearance of beautifully patterned butterfly wings, with long tails of colder gas and dust streaming away.
Both are reflection nebulas, so called because they reflect the light of nearby stars, revealing them even at visible wavelengths.
Extensive networks of cool gas and dust weave throughout the scene in the form of red and yellow filaments, some of which may host newly forming lightweight stars.
The new Hubble view, taken at near-infrared wavelengths with its Wide Field Camera 3 to celebrate the 23rd anniversary of the launch of the observatory, zooms in on the Horsehead to reveal fine details of its structure.
Nearby stars illuminate the backlit wisps along the upper ridge of the nebula in an ethereal glow. The harsh ultraviolet glare from these bright stars is slowly evaporating the dusty stellar nursery. Two fledgling stars have already been exposed from their protective cocoons, and can just be seen peeking out from the upper ridge.
These latest views are also presented in a new fly-through animation, which puts the Horsehead in context and shows it at both visible and infrared wavelengths. The new views from Herschel and Hubble are complemented by ground-based images from other telescopes.
The Herschel image was obtained as part of a wider study of the Orion B region for the Herschel Gould Belt Survey, a guaranteed-time key programme of the mission. The image is a composite of individual images made at wavelengths of 70 microns (blue), 160 microns (green) and 250 microns (red).
A paper describing these results “What determines the density structure of molecular clouds? A case study of Orion B with Herschel,” by N. Schneider et al., is published in Astrophysical Journal Letters, 766, L17, April 2013.
The Hubble Space Telescope image depicts the Horsehead Nebula at near-infrared wavelengths of 1.1 microns (blue/cyan) and 1.6 microns (red/orange). It was photographed by the Wide Field Camera 3 to mark the 23rd anniversary of its launch on the Space Shuttle in April 1990. Wide Field Camera 3 was installed on the space telescope by astronauts during the 2009 servicing mission.