The James Webb Space Telescope Early Release Science (ERS) programme, which was initially made available on July 12, 2022, has proven to be a veritable gold mine of new scientific discoveries.
The study of Resolved Stellar Populations (RSTs), which was the focus of ERS 1334, is one of the numerous fields of research that it is enabling.
This is used to describe vast clusters of stars that are close enough for individual stars to be seen yet far enough apart for telescopes to see several of them at once. The Milky Way’s neighbouring Wolf-Lundmark-Melotte (WLM) dwarf galaxy serves as an excellent illustration.
One of the principal investigators for the Webb ERS programme, Kristen McQuinn is an assistant professor of astrophysics at Rutgers University whose research focuses on RSTs. She recently discussed how the JWST has made it possible for new investigations of the WLM with Natasha Piro, a NASA senior communications expert.
The more accurate observations from Webb have shown that this galaxy has not previously interacted with other galaxies.
This makes it an excellent option for astronomers to test ideas of galaxy creation and development, claims McQuinn. The highlights of that interview are listed here.
With a distance of about 3 million light-years from Earth, the WLM is relatively close to the Milky Way. Its relative isolation, though, leads astronomers to believe that it hasn’t previously interacted with other systems.
Astronomers have noted that other neighbouring dwarf galaxies are frequently entangled with the Milky Way, indicating that they are in the process of merging, when they have examined these nearby dwarf galaxies.
As a result, it is more difficult to discern between their population of stars and gas clouds and our own.
The fact that WLM contains few elements heavier than hydrogen and helium is another significant feature of the substance (which were very prevalent in the early Universe). Early population stars’ cores produced elements including carbon, oxygen, silicon, and iron, which were then spread when the stars exploded in supernovae.
The power of these explosions has over time driven these elements out in the case of WLM, which has undergone star formation throughout its lifetime. Small, low-mass galaxies have been used to observe this process, known as “galactic winds.”
The most crystal-clear view of WLM has ever been seen in the new Webb photographs. Previously, the dwarf galaxy was captured on camera by the Spitzer Space Telescope’s Infrared Array Camera (IAC) (SST).
As may be seen in the side-by-side comparison, these have lower resolution than the Webb photos (shown below).
As you can see, Webb’s infrared optics and sophisticated suite of instruments offer a significantly deeper perspective that enables the differentiation of individual stars and characteristics. According to McQuinn, it was
“Numerous stars of various shapes, ages, temperatures, and stages of evolution are seen, as well as intriguing nebular gas clouds within the galaxy, foreground stars with Webb’s diffraction spikes, and background galaxies with unique characteristics like tidal tails. It’s a really beautiful picture.”
The ERS Initiative
The primary scientific goal of ERS 1334 is to advance knowledge gained with Spitzer, Hubble, and other space telescopes to better understand the evolution of star creation in galaxies, as McQuinn outlined.
Specifically, they are employing Webb’s Near-Infrared Camera (NIRCam) and Near-Infrared Imaging Slitless Spectrograph to carry out detailed multi-band imaging of three resolved star systems within a Megaparsec (about 3,260 light-years) of Earth (NIRISS).
These include the star-forming WLM dwarf galaxy, the ultra-dwarf Draco II dwarf galaxy, and the globular cluster M92.
Because low-mass stars are so common in WLM and have such lengthy lifetimes, it is possible that some of the stars observed there now formed in the early Universe.
We can learn more about what transpired in the very distant past by figuring out the characteristics of these low-mass stars, such as their ages, said McQuinn.
By examining high-redshift systems, where we can view galaxies as they were when they initially formed, we can learn a lot about the early formation of galaxies.
Another goal is to calibrate the JWST using the WLM dwarf galaxy so that it can detect star brightness extremely accurately. This will enable astronomers to test stellar evolution theories in the near-infrared.
Additionally, McQuinn and her coworkers are creating and testing open-source software that will allow anyone to measure the brightness of resolved stars seen on camera by the NIRCam.
Their ESR project’s outcomes will be made public prior to the Cycle 2 Call for Proposals (27 January 2023).
Despite spending less than a year in space, the James Webb Space Telescope has already shown that it is an important tool. Deep field photos, incredibly accurate measurements of galaxies and nebulae, and rich spectra from extrasolar planet atmospheres are just a few of the spectacular views of the cosmos it has offered.
It has already facilitated numerous scientific discoveries that are nothing short of ground-breaking. There are expected to be some genuinely paradigm-shifting discoveries before the mission’s intended 10-year finish (which could be extended to 20).