A Cosmic Tarantula Caught by Webb
A Cosmic Tarantula Caught by Webb, At the dawn of time and space, the following cosmic creation myth took place: With NASA’s James Webb Space Telescope, tens of thousands of newborn stars in a stellar nursery known as 30 Doradus were revealed.
The Tarantula Nebula has long been a favorite of astronomers investigating star formation due to the appearance of its dusty filaments in prior telescopic photos. Webb not only exposes young stars, but also the complex structure and chemical makeup of the nebula’s gas and dust, as well as distant background galaxies.
The Tarantula Nebula is the largest and brightest star-forming region in the Local Group, the galaxies nearest to our Milky Way, and is located only 161,000 light-years distant in the Large Magellanic Cloud galaxy. It contains the most massive and energetic stars known to science.
Three of Webb’s high-resolution infrared instruments were trained on the Tarantula by astronomers. Webb’s Near-Infrared Camera (NIRCam) images reveal a region that looks like the burrow of a tarantula, complete with silk lining. Radiation from a group of massive young stars, which shine pale blue in the NIRCam image, has carved out a cavity in the middle of the nebula.
As the stellar winds from these stars erode the surrounding nebula, only the densest regions remain, generating pillars that seem to point back toward the cluster. Protostars are being born within these pillars of dust, and they will ultimately emerge from their nebula-forming cocoons and assume their places in the spotlight.
One very young star was observed by Webb’s Near-Infrared Spectrograph (NIRSpec) when it was doing this. Prior to this discovery, astronomers speculated that this star was a bit older and already in the process of clearing out a bubble around itself.
NIRSpec, however, revealed that the star was only beginning to emerge from its pillar and still maintained an insulating cloud of dust surrounding it. Webb’s high-resolution spectra at infrared wavelengths showed this active era of star creation.
Longer infrared wavelengths observed by Webb’s Mid-infrared Instrument render a distinct visual appearance change to the region (MIRI). Cooler gas and dust sparkle while the blazing stars fade. Bright dots within the cloudy star nurseries are embedded protostars that are still accumulating mass. Mid-infrared light can see through the dust that obscures the nebula’s surroundings in visible light, revealing a hitherto hidden part of the cosmos to the Webb telescope.
The chemical composition of the Tarantula Nebula is similar to that of the massive star-forming areas seen during the “cosmic noon” of the universe when star creation was at its zenith and the cosmos was just a few billion years old.
Our Milky Way galaxy’s star-forming regions are chemically distinct from the Tarantula Nebula, and they do not produce stars at the same frenzied rate. As such, the Tarantula is the best (most easily observed) illustration of what the universe looked like at its brightest noon.
Webb will allow scientists to examine deep images of faraway galaxies from the actual epoch of cosmic noon and compare them to studies of star creation in the Tarantula Nebula.
After thousands of years of stargazing, we still don’t know a lot about how stars are formed, and much of that mystery stems from our inability to see clearly what’s going on behind the dense clouds of stellar nurseries.
Webb is just getting started on rewriting the stellar origin tale, but he has already begun unveiling a world unlike any seen before.
