How JWST’s first science images will blow us all away

In astronomy, we study the Universe by gathering light.

Astronomers have used this set of single-color images, shown around the edge, to construct the color picture (centre) of a ring of star clusters surrounding the core of the galaxy NGC 1512. By adding together a series of images taken with different photometric filters, a rich color image, with essential details about temperature, dust, and more, can be produced.

Using visible light alone, however, is incredibly restrictive.

Although visible light gives us a rich and varied view of objects in the Universe, it represents only a tiny fraction of the electromagnetic spectrum. The range from 0.4 to 0.7 microns, which is perceptible to human vision, is only a tiny blip compared to JWST’s wavelength range of 0.5-to-28 microns, or of the full electromagnetic spectrum, whose wavelength ranges from sizes of a subatomic particle, like a proton, up to the sizes of planets.

Spanning only the wavelengths from 400-700 nanometers, optical astronomy overlooks most features.

The Andromeda galaxy, the closest large galaxy to Earth, displays a tremendous variety of details depending on which wavelength or set of wavelengths of light it’s viewed in. Even the optical view, at top left, is a composite of numerous different filters. Shown together, they reveal an incredible set of phenomena present in this spiral galaxy. Multiwavelength astronomy can shed unexpected views on almost any astronomical object or phenomenon, revealing details in one wavelength that are wholly invisible in another.

But multiwavelength astronomy can reveal otherwise unseen details.

The Helix Nebula, the dying remnant of a formerly Sun-like star, reveals its gas distribution in visible light, but shows a set of obscured features that appear knotted and fragmented in infrared light. Multiwavelength views can reveal features that do not appear in only one set of wavelengths of light.

In particular, dusty, star-forming regions house spectacular phenomena just waiting to be uncovered.

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. What appears to be a single star at the nebula’s center was identified as a binary back in 2005, and it’s led some to theorize that a third companion was responsible for triggering the supernova impostor event of the 19th century. Eta Carinae is still a compelling supernova candidate today.

One of Hubble’s most iconic targets is the Pillars of Creation.

Located within the Eagle Nebula, a great cosmic race concludes there, some 7000 light-years away.

This 3-D visualization of the location and properties of the feature that appears as the Pillars of Creation in the Eagle Nebula is actually composed of at least four different, disconnected components which are on either sides of a rich star cluster: NGC 6611. The neutral matter both absorbs and reflects starlight, leading to its unique appearance at optical wavelengths, and spectacular sights when viewed in infrared by JWST.

Visible light showcases neutral matter, absorbing and reflecting the light from surrounding stars.

This visible light image of a large section of the Eagle Nebula was taken from the ground with an amateur setup in 2019. It reveals a number of iconic feature inside, including the young stars and the dense, dusty regions where new stars are forming. The Pillars of Creation, at center, reflects and absorbs starlight, leading to its iconic appearance.

Inside, new stars actively form, evaporating the pillars from the inside.

This largely unfamiliar view of the Pillars of Creation showcases the limits of the Hubble Space Telescope’s capabilities: reaching into the near-infrared to peer through the neutral matter of the pillars and into the stars forming inside. Most of the stars are background objects, behind the pillars, but a few are proto-stars currently forming inside of them. Later in 2022, the James Webb Space Telescope will view this region of space for the first time, revealing details that humanity has never seen before.

Outside, external stellar radiation boils the neutral matter away.

By rotating and stretching Hubble’s two iconic, high-resolution images of the tip of the tallest pillar relative to one another, the changes from 1995 to 2015 can be overlaid. Contrary to the expectations of many, the evaporative process is slow and small, indicating that the pillars will persist for ~100,000 years or more.

The race is to form new stars, inside, before the gas disappears entirely.

The Pillars of Creation are some of the last remaining dense knots of neutral, star-forming matter inside the Eagle Nebula. From the outside, hot stars irradiate the pillars, boiling the gas away. Inside the pillars, matter collapses and new stars form, which also irradiate the pillars from the inside. We are bearing witness to the last gasps of star-formation inside this region.

Hubble’s dual images, separated by 20 years, show this structure evolving.

This image compares two views of the Eagle Nebula’s Pillars of Creation taken with Hubble 20 years apart. The new image, on the left, captures almost exactly the same region as in the 1995, on the right. However, the newer image uses Hubble’s Wide Field Camera 3, installed in 2009, to capture light from glowing oxygen, hydrogen, and sulphur with greater clarity, as well as with a greater field of view. The pillars are changing over time very slowly; it should take hundreds of thousands of years for evaporation to complete.

But other wavelengths of light reveal what’s happening beneath the dust.

Chandra’s unique ability to resolve and locate X-ray sources made it possible to identify hundreds of very young stars, and those still in the process of forming (known as “protostars”). Infrared observations from NASA’s Spitzer Space Telescope and the European Southern Observatory indicate that 219 of the X-ray sources in the Eagle Nebula are young stars surrounded by disks of dust and gas and 964 are young stars without these disks: combined, more than 1000 new stars and protostars have been found. And no, there were no indications of recent supernovae or supernova remnants discovered; the Pillars are not in the process of being destroyed.

X-ray wavelengths, from NASA’s Chandra, reveal new stars and stellar remnants.

Using Chandra, researchers detected over 1,700 X-ray sources in the field of the Eagle Nebula. Two thirds of these sources are likely young stars located in the nebula, and some of them are seen in this small field of view around the Pillars of Creation. Although most of the sources aren’t coming from within the pillars themselves, the “eye” of the largest pillar corresponds to a protostar about 5 times the mass of the Sun. The pillars themselves represent some of the last stores of gas in the nebula’s interior that have not yet been fully photoevaporated.

Near-infrared views peer through the dust, exposing young stars inside.

This infrared view of the Pillars of Creation from the ESO’s Very Large Telescope, an 8.2 meter ground-based telescope, largely peers through the dust of the Pillars of Creation to reveal the stars forming inside. JWST’s views are in similar wavelengths, but are much higher-resolution, much more detailed, and span a much greater range in wavelengths.

The far-infrared eyes of Herschel exposed cool, neutral matter, which will subsequently form new stars.

This Herschel image of the Eagle Nebula shows the heat-based emission of the intensely cold nebula’s gas and dust as only far-infrared views can capture. Each color shows a different temperature of dust, from around 10 degrees above absolute zero (10 Kelvin or minus 442 degrees Fahrenheit) for the red, up to around 40 Kelvin, or minus 388 degrees Fahrenheit, for the blue. The Pillars of Creation, identifiable just below and to the left of center, are among the hottest parts of the nebula as revealed by these wavelengths. Far-IR observatories reveal features that cannot be seen at any other wavelength.

NASA’s Spitzer previously looked in JWST’s wavelengths.

This infrared, composite view of multiple channels from NASA’s Spitzer Space Telescope, taken in 2007, reveals the “Pillars of Creation” at right and the “Spire” or “Fairy” at left, similar to the iconic features revealed by Hubble in optical wavelengths. JWST has yet to image the Fairy, but its dense, central core of gas may yet outlast the neutral matter present in the pillars.

With vastly superior light-gathering power and resolution, it’s JWST’s perfect “first science” target.

Although Spitzer (launched 2003) was earlier than WISE (launched 2009), it had a larger mirror and a narrower field-of-view. Even the very first JWST image at comparable wavelengths, shown alongside them, can resolve the same features in the same region to an unprecedented precision. This is a preview of the quality of the science we’ll get with JWST.

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.