Our last view of the Universe before JWST’s big reveal
The James Webb Space Telescope has chosen 5 targets for its first science release. Here’s what we know on the eve of JWST’s big reveal!
This animation showcases a portion of the Hubble eXtreme Deep Field, with 23 days of cumulative data, and a simulated view of what scientists expected JWST might see when it viewed this region. This simulation predates JWST's launch, and has since been spectacularly superseded by actual JWST data.
Credit: NASA/ESA and Hubble/HUDF team; JADES collaboration for the NIRCam simulation
Key Takeaways
- The James Webb Space Telescope, or JWST for short, is now fully cooled, calibrated and commissioned, and its first full-color, science images release on July 12, 2022.
- But before they do, other observatories, such as Hubble, have already acquired an up-to-date view of what these targets look like.
- Although JWST will blow these images away, it’s absolutely worth taking a look at what we see and know today, before the big reveal, as it makes the first science release all the more informative.
Merely 7 months post-launch, the James Webb Space Telescope‘s first science results arrived.
This image, of a dusty region of the Large Magellanic Cloud, was taken with JWST’s MIRI instrument at a wavelength of 7.7 microns. By measuring the Universe at unprecedented wavelengths, depths, sensitivities and resolutions, JWST can reveal details that have never been revealed before. From dust to stars to black holes and even to potential biosignatures, its capabilities could show us a Universe we never even expected to find.
Its initial five targets will change astrophysics forever.
The Pillars of Creation, shown in visible (L) and infrared (R) views as imaged by Hubble, may be one of JWST’s first-year science targets, but won’t be part of the very first release results. When JWST views it, the new telescope will reveal features inside at precisions and over wavelength ranges never seen before, opening up a tremendous possibility for new, surprising discoveries.
Here’s what’s known prior to JWST’s big reveal.
The Carina Nebula, as seen with a wide-field, visible light view. Eta Carinae and the Keyhole Nebula are just left of center, while NGC 3324 is at upper right. Although most of the interesting features are contained within the innermost ~100 light-years or so, the nebula itself extends for over 250 light-years.
1.) Carina Nebula.
Within the tempestuous Carina Nebula lies “Mystic Mountain.” This three-light-year-tall cosmic pinnacle, imaged by the Hubble Space Telescope’s Wide Field Camera 3 in 2010, is made up primarily of dust and gas, and exhibits signs of intense star-forming activity. The colors in this composite image correspond to the glow of oxygen (blue), hydrogen and nitrogen (green) and sulfur (red).
This hotbed of star-formation spans 250 light-years.
With over 2 decades of Hubble observations, including in ultraviolet light, astronomers have newly revealed some striking features, including streaks (in blue) emerging from the lower-left lobe. These streaks are created when the star’s light rays poke through the dust clumps scattered along the bubble’s surface. Wherever the ultraviolet light strikes the dense dust, it leaves a long, thin shadow that extends beyond the lobe into the surrounding gas.
It contains Eta Carinae: our closest supernova impostor.
The Carina Nebula, shown in visible (top) and near-infrared (bottom) light, has been imaged by the Hubble Space Telescope in a series of different wavelengths, allowing these two very different views to be constructed. The gas burning off in the Carina Nebula may be clumping into planet-like and planet-sized objects, but the luminosity and the ultraviolet radiation from the massive stars driving the evaporation will almost certainly boil it all away before most of these clumps can grow into stars themselves.
We’ve viewed its components in infrared light before.
This picture of the Carina Nebula, a region of massive star formation in the southern skies, compares the view in visible light with a comparable picture taken in infrared light. Many features that are not seen at all in visible light can be seen in great detail in the 2012 infrared image from the VLT.
JWST’s views will be sharper, deeper, and longer-wavelength than ever.
This labeled image identifies some of the significant features in the Carina Nebula’s central region. Several of the brightest stars are identified by their catalog numbers, and are among the most massive stars known. The nebula itself is a hotbed of stellar birth and death.
2.) WASP-96b.
This artistic rendition shows the gas giant planet WASP-96b: a hot exoplanet about the size of Jupiter but only about half of Jupiter’s mass, in close orbit around its parent star: a G-class star just like our Sun. The closer a planet is to its parent star, the more wild and exotic its various forms of precipitation will be.
This “hot Jupiter” orbits its star every 3.4 days.
Most exoplanets that have had their atmospheres measured possess thick layers of clouds that cannot be seen through. But WASP-96b is unusual in that its spectrum shows an absence of clouds entirely, providing a characteristic signature for the element sodium. With its novel spectroscopy capabilities, JWST could reveal a whole lot more than any other tool.
The exoplanet spectrum upcoming from JWST will reveal its atmosphere’s details.
The NIRSpec instrument, now fully commissioned, will be capable of measuring the spectra of many different objects at once, as well as to take spectra of separate components of sufficiently large, luminous objects. Whatever contents are present in an exoplanet’s atmosphere, spectroscopy will help reveal.
Someday, similar technology will discover our first inhabited exoplanet.
NGC 3132 is a striking example of a planetary nebula. This expanding cloud of gas, surrounding a dying star, is known to amateur astronomers in the southern hemisphere as the ‘Eight-Burst’ or the ‘Southern Ring’ Nebula.
3.) Southern Ring Nebula.
This unusual view of the Southern Ring Nebula highlights the neutral oxygen signal found in the outskirts of the bubble walls, better revealing the 3D shape of the nebula itself.
This planetary nebula arises from an isolated, dying, Sun-like star.
From their earliest beginnings to their final extent before fading away, Sun-like stars will grow from their present size to the size of a red giant (~the Earth’s orbit) to up to ~5 light-years in diameter, typically. The largest known planetary nebulae can reach approximately double that size, up to ~10 light-years across, but none of this necessarily means that the Sun is a typical, average star.
JWST will identify atomic and molecular abundances, mapping temperatures throughout.
When our Sun runs out of fuel, it will become a red giant, followed by a planetary nebula with a white dwarf at the center. The Cat’s Eye nebula is a visually spectacular example of this potential fate, with the intricate, layered, asymmetrical shape of this particular one suggesting a binary companion. At the center, a young white dwarf heats up as it contracts, reaching temperatures tens of thousands of Kelvin hotter than the surface of the red giant that spawned it. The outer shells of gas are mostly hydrogen, which gets returned to the interstellar medium at the end of a Sun-like star’s life.
Such measurements help scientists understand stellar life cycles.
The first compact group of galaxies to ever be discovered Stephan’s Quintet is actually a larger, more extended group of a greater number of galaxies some 290 million light-years away with one interloping foreground galaxy just 40 million light-years distant.
4.) Stephan’s Quintet.
This composite image of Stephan’s Quintet showcases X-ray light and the new, young stars that are being formed from the interactions of the gas within and between galaxies. The foreground spiral galaxy has faint X-ray emissions; the interacting pair in the background is a much stronger X-ray emitter.
This compact galaxy group features four interacting galaxies with one foreground member.
These cosmic smash-ups are vital to galaxy growth and evolution.
This close-up look at the details from the tightly interacting pair of galaxies within Stephan’s Quintet showcases stellar streams and the interface of colliding gas, from which new stars arise. With superior resolution and the ability to probe much longer wavelengths than Hubble, JWST will show us details and components of these galaxies that were unknown before its launch.
JWST will resolve novel details about the stars, gas, and dust inside.
This wide-field view of the region around Stephan’s Quintet shows additional galaxies, extended features of distended arms and stellar streams, and foreground stars in the Milky Way. One spectacular feature, outside of the main galaxies themselves, are distant, faint smudges on the image: ultra-distant galaxies of their own. JWST will be spectacular at revealing them.
5.) SMACS 0723.
This image of galaxy cluster SMACS 0723 has been constructed from blue, green, and red filters aboard Hubble, along with four infrared filter views of the cluster’s central regions. Hubble viewed this object to wavelengths of ~1600 nanometers; JWST will go three times as far in the near-infrared alone. It may, in its very first science release, break the record for most distant galaxy discovered of all.
The massive galaxy cluster, itself, isn’t the focus.
An illustration of gravitational lensing showcases how background galaxies — or any light path — is distorted by the presence of an intervening mass, but it also shows how space itself is bent and distorted by the presence of the foreground mass itself. When multiple background objects are aligned with the same foreground lens, multiple sets of multiple images can be seen by a properly-aligned observer.
Its gravity bends and distorts spacetime, magnifying background objects.
A Hubble Space Telescope view of the galaxy cluster MACS 0416 is annotated in cyan and magenta to show how it acts as a ‘gravitational lens,’ magnifying more distant background sources of light. Cyan highlights the distribution of mass in the cluster, mostly in the form of dark matter. Magenta highlights the degree to which the background galaxies are magnified, which is related to how the mass is specifically distributed within the cluster.
Gravitational lensing uncovers the most distant extragalactic objects.
From the distant Universe, light has traveled for some 10.7 billion years from distant galaxy MACSJ2129-1, lensed, distorted and magnified by the foreground clusters imaged here. Gravitational lensing can reveal fainter and more distant objects than can be seen by any non-lensed region of space, with cluster surveys holding the greatest potential for breaking the cosmic distance record.
Unprecedented
- wavelength coverage,
- resolution,
- and light-gathering power
herald the JWST era.
Amidst the dense arcs and faint red blobs surrounding the central regions of galaxy cluster SMACS 0723 are likely fainter, more distant objects whose light is shifted too far into the infrared for Hubble to see it. With JWST now upon us, a whole host of never-before-seen features are about to be unveiled. At long last, the JWST era has arrived.
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