The James Webb Space Telescope lives up to the expectations placed on it. It has captured the clearest infrared images to date of one of the iconic astronomical objects, the Horsehead Nebula, also known as Barnard 33. These observations show a part of the iconic nebula in a whole new light, capturing its complexity with unprecedented spatial resolution according to NASA, which has released a combination of images of the nebula taken by Euclid, Hubble, and now the JWST.
The Horsehead Nebula, also known as Barnard 33, is one of the iconic astronomical objects. It was first discovered in 1888 by Williamina Fleming on a photographic plate taken at the Harvard College Observatory. However, it was the American astronomer Edward Emerson Barnard (a famous star bears his name) who shortly after would describe it and include it in his catalog of dark nebulae, which are regions where interstellar dust appears to concentrate in large clouds that appear as star-poor regions.
Located about 1,300 light-years from the Solar System in the constellation of Orion, on the western side of the Orion B molecular cloud, Barnard 33 is not easy to see, explaining its late discovery. Amateur astronomers need substantial equipment to photograph it, although it is possible to observe it to some extent with an eVscope.
A Nebula Illuminated by a Quintuple Star
However, the Horsehead Nebula is perfectly accessible with instruments like the Euclid, Hubble, and James Webb telescopes. NASA has just revealed a combination of images from these three eyes of the noosphere.
The publication of an article in Astronomy & Astrophysics, available for free on arXiv.
In this article, Barnard 33 is presented through the clearest infrared images to date, thanks to the Miri and NIRCam instruments of the James-Webb capturing the complexity of the gas turbulence in the Horsehead Nebula with unprecedented spatial resolution.
What Barnard and Fleming did not know is that this dark nebula is the result of the gravitational collapse of a cloud of gas and dust sculpted by the ultraviolet radiation from a hot star, Sigma Orionis. This star is a quintuple star whose radiation ionizes the hydrogen gas behind the nebula, giving it a red color, while in the foreground lies the Barnard 33 nebula itself, which strongly absorbs the visible radiation emitted by the ionized gas in the background.
A laboratory to understand the physics and chemistry of the interstellar medium
Astrophysicists believe that the dusty and dense head-shaped structure of the Horsehead Nebula, which currently withstands the light flux and photodissociation it causes, is not eternal and will have dissipated in about 5 million years. Today, the James-Webb can still zoom in on the illuminated edge of the horse’s head.
Barnard 33 is an example of dense and cold molecular clouds which, within 5 million years, will have dissipated.Gravity-collapsing clouds give birth to new stars forming open clusters. The radiation from Sigma Orionis, however, allows the study of the physics and chemistry of such clouds at the very beginning of their collapse. The Horsehead Nebula, an example of a photodissociation region (PDR), serves as a laboratory to better understand the interstellar environment and the star formation process.
Due to its proximity and almost edge-on geometry, the Horsehead Nebula is an ideal target for astronomers wishing to study the physical structures of PDRs and the evolution of the chemical characteristics of gas and dust in their respective environments, as well as the transition regions between them.
It is considered one of the best objects in the sky for studying the interaction of radiation with interstellar matter, according to a NASA statement.