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The Road Ahead for Webb

JWST,Brown Dwarfs,Dark Matter
Mihir Tripathy
Cassie Popeski
August 9, 202210:00 AM UTC (UTC +0)

Researchers are finally doing the science they’ve wanted to for decades.

Webb is the largest space observatory ever built and it enables us to see light emitted just after the big bang, providing a sneak peek into the early development of the universe. Just like Hubble, Webb will also have annual calls for scientists all over the globe to send in proposals for the observatory. The Space Telescope Science Institute (STScI) handpicks the science programs for each year of observations.

"The first year of science observations has already begun. We have already taken data for scientists who want time in the first year," Klaus Pontoppidan, chief Webb project scientist at STScI, said during a media event in July.

"We're just going full steam ahead."

Pontoppidan also emphasized that the early observation program selected the science targets based in part on efficiency — such that the time taken for moving from target to target is minimized.

Webb beams a huge amount of raw data down to Earth, so much so that NASA has arranged for extra server space to be available in anticipation of heavy traffic attempting to download and access the new data.

"The point is to make sure that there's even more data available from all the instruments, and all the modes are spanning a wide range of science, that is public immediately [and] has no exclusive access period," said Pontoppidan. "And so they get priority, because we want the community to have as much data available, in particular by the time they get to propose again."

"I just want to make it clear that this is just the very beginning,” said Jane Rigby, operations project scientist for Webb at NASA’s Goddard Space Flight Center in Maryland. "The data demonstrates that the telescope works, but the science results are going to be rolling out from here on in. People are going to use lots of different techniques to get as much science as they can out of the data.”

Webb has 4 major instruments onboard which receive and process ancient photons from the far reaches of the universe, namely the Mid-Infrared Instrument (MIRI), Near-Infrared Camera (NIRCam), Near Infrared Spectrograph (NIRSpec), and Near-Infrared Imager and Slitless Spectrograph / Fine Guidance Sensor (NIRISS/FGS).

While they allow researchers to study a wide range of objects and phenomena, what makes these instruments unique is their specific combination of components, observing modes, wavelength ranges, field of view, and resolutions. Some investigations may be conducted with a single instrument and observing mode, but most will rely on multiple, used in concert.

As NASA's new flagship observatory enters its operational phase, what can we hope to learn?

Jupiter and its moon Europa are seen through the James Webb Space Telescope’s NIRCam instrument 2.12 micron filter. Credits: NASA, ESA, CSA, and B. Holler and J. Stansberry (STScI)

Protoplanetary Disks

New Stars are born inside clouds of gas and dust. When the force of gravity pulling in on the cloud is greater than the internal pressure pushing out, this cloud collapses. Its material then falls inward which quickly flattens into a disk that surrounds the newly-born star.

If these disks are massive enough, they lead to the formation of planets and moons. They are relatively cooler and emit most of their light in mid-infrared while blocking most of the visible spectrum, making the Webb’s Mid-Infrared Instrument (MIRI) crucial for their observation. MIRI’s imaging and spectroscopy capabilities allow the researchers to get an insight into the composition of these protoplanetary disks.

MIRI will obtain spectroscopy of three protoplanetary disks, known to contain traces of water. These deep spectra will be used to search for water and important carriers of nitrogen and carbon. The volatility of such compounds will help determine the amount of carbon, nitrogen, and oxygen available for accretion onto such planets, and provide a comparison to other exoplanets' atmospheric chemistry.

Insights from these studies will provide clues to where and how planets form, how they become habitable, whether they change orbits after formation, and will shed light on the formation of our own system.

Brown Dwarfs

Brown dwarfs are substellar objects that exhibit properties of both planets and stars. These astronomical bodies weigh significantly more than our largest planet Jupiter, but are not massive enough to sustain the fusion of hydrogen like a regular star — thus, they're commonly referred to as “failed stars.” Such similarities make their formation process uncertain. Scientists want to know if it’s like a star where the gasses are heavily compressed, or like a planet, formed by the accretion of material in a protoplanetary disk.

Webb’s Near-Infrared Spectroscope (NIRSpec) will obtain low and medium-resolution near-IR spectra of known and candidate brown dwarfs in two nearby star-forming clusters. The Near-Infrared Camera (NIRCam) will conduct a survey of the inner regions of the Orion Nebula Cluster to detect cool brown dwarfs and other objects to provide selection criteria based on factors like age and surface gravity.

These studies might help achieve a deeper understanding of the nature of brown dwarfs — their formation, atmospheres, temperature, and even the nature of clouds on a brown dwarf world. 

A large speckled galaxy resembling a wheel with two smaller spiral galaxies about the same size to the left against a black background.
Credits: NASA, ESA, CSA, STScI

Exoplanets

NASA has been conducting a long term campaign to search and catalog planets which exist outside the Solar System. Building off this work primarily from the Kepler and Spitzer Space Telescopes, researchers specifically plan to use spectral capabilities in the mid-infrared to observe and determine the atmospheric composition of the 55 Cancri e exoplanet, also known as Janssen. Located 41 light years away, Janssen orbits a star called Copernicus.

That’s not all. Webb will observe tens of hundreds of exoplanets to study their atmospheres, determining which elements are present and what they indicate about those worlds, including their potential to support life. Another interesting target is HD 206893 B, located 125 light years away. Ever since its discovery back in 2016, its distinct red color has been a mystery. Researchers plan to use Webb’s NIRISS instrument to study the composition and size distribution of the dust grains which cause the red color. Moreover, they aim to unravel its formation history and resolve the uncertainty about its age and mass.

Webb already observed the transit of WASP-96b as it passed in front of its host star. As the starlight filtered through the atmosphere, the telescope's instruments measured the wavelengths of light, light that is full of information to help understand the complicated chemistry of this planet's atmosphere. The spectrum indicates the presence of water vapor in the atmosphere.

“These bumps and wiggles reveal the telltale signature of water vapor,” Collon said, “as well as evidence of clouds and hazes. While this hot, giant planet is nothing like our solar system’s planets, that’s ok. This is just the beginning, Webb’s observation demonstrates the telescope’s ability to analyze atmospheres of planets hundreds of light-years away, and we’ll be able to look at smaller planets soon.”

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Star Formations

Webb’s instruments can investigate spatial variations in spectra, and capture individual spectra of dozens of objects at once using a micro shutter array, making it ideal to study extremely distant and faint stars and galaxies. This will help researchers piece together the lifecycle of the earliest stars.

The observatory will use MIRI and NIRCam to image several star-forming clusters in the distant Digel Cloud 1 and Digel Cloud 2. The data from the images will be used to estimate their mass, luminosity, and evolutionary status, allowing the researchers to study star formation activities. Researchers are hoping to answer questions not only about their formation, but also about the deviation of stars’ life cycles over the course of deep time.

Webb will help us fill in the blanks in the earliest chapters of our history, improving our understanding of how the universe functions.

Galaxy Assembly and Dark Matter

Astronomers estimate that all massive galaxies may have undergone at least one major merger during the early period of universe formation. Webb’s spectroscopic instruments can help researchers figure out the driving force behind this activity, and the cause of its sudden decline, while also shedding light on the formation of heavier elements and entire galaxies.

Webb will be observing Draco and the Sculptor dwarf galaxies using NIRCam to study their internal motion. It’ll help reveal details about the merging process and shed light on the rotation rate, mass, and the process of formation of such galaxies, including how stars came together to form the very first galaxies in the universe. From this data, astronomers can also determine the total mass of the galaxy needed for gravity to keep it from springing apart. The difference between this and the observed mass will give us another clue about dark matter.

Dark Matter — which we can’t detect yet — plays a key role in holding the galaxy together and determining its shape and structure. Better understanding it will tell us how galaxies changed over time and what role black holes play in the evolution of early individual stars and galaxies like our own.

Deep Fields

Canadian-made Near-Infrared Imager and Slitless Spectrograph / Fine Guidance Sensor (NIRISS/FGS) can help perform deep field observations similar to the Hubble Space telescope.

The first image released by the JWST committee was a deep field observation of a patch of sky approximately the size of a grain of sand held at arm’s length. Webb’s capabilities to observe in infrared will push the boundaries of what is observable in the universe back much farther, and help us get the first images of the chaotic galaxies that existed 10 billion years ago.

"Everything we planned through Cycle 1, the astronomical community, was bold, but it wasn't bold enough," said Eric Smith, chief scientist at NASA's astrophysics division and program scientist for JWST. "So I'm really excited for what people now plan to do for the second cycle, seeing just how capable the facility is.”

That second cycle, which will begin next summer, could lead to some surprising discoveries thanks to the new levels of scientific detail that Webb will be able to capture.

"We're turning the page now on several new chapters, on exoplanet atmospheres, early universe, cloud formation, you name it," René Doyon, principal investigator of Webb's Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument, said during the news conference. "And we don't even know what we're going to find. It's exciting."

Mihir Tripathy
Cassie Popeski
August 9, 202210:00 AM UTC (UTC +0)