 |
| In this mosaic image stretching 340 light-years across, Webb’s Near-Infrared Camera (NIRCam) displays the Tarantula Nebula star-forming region in a new light, including tens of thousands of never-before-seen young stars that were previously shrouded in cosmic dust. The most active region appears to sparkle with massive young stars, appearing pale blue. Scattered among them are still-embedded stars, appearing red, yet to emerge from the dusty cocoon of the nebula. NIRCam is able to detect these dust-enshrouded stars thanks to its unprecedented resolution at near-infrared wavelengths. To the upper left of the cluster of young stars, and the top of the nebula’s cavity, an older star prominently displays NIRCam’s distinctive eight diffraction spikes, an artifact of the telescope’s structure. Following the top central spike of this star upward, it almost points to a distinctive bubble in the cloud. Young stars still surrounded by dusty material are blowing this bubble, beginning to carve out their own cavity. Astronomers used two of Webb’s spectrographs to take a closer look at this region and determine the chemical makeup of the star and its surrounding gas. This spectral information will tell astronomers about the age of the nebula and how many generations of star birth it has seen. Farther from the core region of hot young stars, cooler gas takes on a rust color, telling astronomers that the nebula is rich with complex hydrocarbons. This dense gas is the material that will form future stars. As winds from the massive stars sweep away gas and dust, some of it will pile up and, with gravity’s help, form new stars. Credit: NASA, ESA, CSA, and STScI |
Thousands of never-before-seen newborn stars have been discovered in 30 Doradus, a stellar nursery photographed by the NASA/ESA/CSA James Webb Space Telescope. The Tarantula Nebula, so named because of the appearance of its dusty filaments in previous telescopic photographs, has long been a favorite of astronomers researching star formation. Webb discovers distant background galaxies as well as the intricate structure and composition of the nebula's gas and dust.
The Tarantula Nebula is the biggest and brightest star-forming area in the Local Group of galaxies, which is just 161,000 light-years away in the Large Magellanic Cloud galaxy. It is regarded to be the home of the hottest, most enormous stars. Three of Webb's high-resolution infrared sensors were directed towards the Tarantula. When seen using Webb's Near-Infrared Camera (NIRCam), the region resembles a burrowing tarantula's silk-lined lair. The NIRCam picture's hole has been hollowed down by blistering radiation from a cluster of huge new stars, which glitter pale blue in the image. Only the densest regions of the nebula's surroundings withstand erosion by the intense stellar winds of these stars, generating pillars that appear to point back toward the cluster. These pillars house growing protostars, which will ultimately emerge from their dusty cocoons and contribute to the formation of the nebula.
One extremely young star was spotted doing precisely that by Webb's Near-Infrared Spectrograph (NIRSpec). Previously, astronomers suspected that this star was older and in the process of cleaning out a bubble around itself. However, NIRSpec revealed that the star was only just emerging from its pillar and was still surrounded by an insulating cloud of dust. This event of star formation-in-action could not have been revealed without Webb's high-resolution spectra at infrared wavelengths.
 |
| Webb’s Near-Infrared Spectrograph (NIRSpec) reveals what is really going on in an intriguing region of the Tarantula Nebula. Astronomers focused the powerful instrument on what looked like a small bubble feature in the image from Webb’s Near-Infrared Camera (NIRCam). However, the spectra reveal a very different picture from a young star blowing a bubble in its surrounding gas. The signature of atomic hydrogen, shown in blue, shows up in the star itself but not immediately surrounding it. Instead, it appears outside the “bubble,” which spectra show is actually “filled” with molecular hydrogen (green) and complex hydrocarbons (red). This indicates that the bubble is actually the top of a dense pillar of dust and gas that is being blasted by radiation from the cluster of massive young stars to its lower right (see the full NIRCam image). It does not appear as pillar-like as some other structures in the nebula because there is not much color contrast with the area surrounding it. The harsh stellar wind from the massive young stars in the nebula is breaking apart molecules outside the pillar, but inside they are preserved, forming a cushy cocoon for the star. This star is still too young to be clearing out its surroundings by blowing bubbles – NIRSpec has captured it just beginning to emerge from the protective cloud from which it was formed. Without Webb’s resolution at infrared wavelengths, the discovery of this star birth in action would not have been possible. Credit: NASA, ESA, CSA, and STScI |
When observed in the longer infrared wavelengths detected by Webb's Mid-infrared Instrument, the area takes on a distinct look (MIRI). Cooler gas and dust sparkle as the blazing stars vanish. Points of light within the stellar nursery clouds suggest embedded protostars that are still accumulating mass. While lesser wavelengths of light are absorbed or deflected by dust grains in the nebula and so never reach Webb, longer mid-infrared wavelengths pierce that dust, exposing a hitherto unexplored cosmic environment.
One of the reasons astronomers are interested in the Tarantula Nebula is that it has a comparable chemical makeup to the massive star-forming areas found at the universe's "cosmic noon," when the universe was just a few billion years old and star creation was at its height. Our Milky Way galaxy's star-forming regions do not produce stars at the same pace as the Tarantula Nebula and have a distinct chemical makeup. As a result, the Tarantula is the closest (i.e., most detailed) illustration of what was going on in the cosmos as it reached its bright high noon. Webb will allow scientists to compare and contrast views of star formation in the Tarantula Nebula with deep studies of distant galaxies from the age of cosmic midday.
Despite thousands of years of stargazing, the star formation process continues to be riddled with mysteries, many of which stem from our inability to obtain clear photographs of what was going on beneath the dense clouds of stellar nurseries. Webb has already begun to disclose a previously unseen cosmos, and he is only getting started on rewriting the stellar origin myth.
0 Comments