The James Webb Space Telescope Early Release Science (ERS) program – first launched on July 12, 2022 – has proven to be a treasure trove of discoveries and scientific breakthroughs.
Among the many areas of research it enables is the study of resolved stellar populations (RST), which was the subject of ERS 1334.
This refers to large groups of stars close enough that individual stars can be discerned but far enough away that telescopes can capture several at once. A good example is the Wolf-Lundmark-Melotte (WLM) dwarf galaxy neighboring the Milky Way.
Kristen McQuinn, an assistant professor of astrophysics at Rutgers University, is a lead scientist in the Webb ERS program whose work focuses on RSTs. Recently, she spoke to Natasha Piro, a senior NASA communications specialist, about how JWST has enabled new studies of WLM.
Webb’s enhanced observations revealed that this galaxy has not interacted with other galaxies in the past.
According to McQuinn, this makes it an excellent candidate for astronomers to test theories of galaxy formation and evolution. Here are the highlights of this interview.
About WLM
The WLM is about 3 million light-years from Earth, which means it’s quite close (in astronomical terms) to the Milky Way. However, it is also relatively isolated, leading astronomers to conclude that it has not interacted with other systems in the past.
When astronomers observed other nearby dwarf galaxies, they noticed that they are usually entangled with the Milky Way, indicating that they are merging.
This makes them more difficult to study since their population of stars and gas clouds cannot be entirely distinguished from ours.
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Another important thing about the WLM is that it is low in elements heavier than hydrogen and helium (which were very common in the early Universe). Elements such as carbon, oxygen, silicon, and iron formed in the cores of early population stars and were dispersed when those stars exploded into supernovae.
In the case of WLM, which has experienced star formation throughout its history, the force of these explosions has repelled these elements over time. This process is known as “galactic winds” and has been observed with small, low-mass galaxies.
JWST Images
The new Webb images provide the clearest view of WLM ever. Previously, the dwarf galaxy was imaged by the Spitzer Space Telescope’s (SST) Infrared Imager (IAC).
These provided limited resolution compared to the Webb images, which can be seen in the side-by-side comparison (shown below).
As you can see, Webb’s infrared optics and suite of advanced instruments provide a much deeper view that can differentiate between stars and individual features. As McQuinn described it:
“We can see a myriad of individual stars of different colors, sizes, temperatures, ages and stages of evolution; interesting clouds of nebular gas in the galaxy; prominent stars with spikes Webb diffraction; and background galaxies with neat features like tidal tails. It really is a stunning image.”
The ERS program
As McQuinn explained, the main scientific goal of ERS 1334 is to build on previous expertise developed with Spitzer, Hubble and other space telescopes to learn more about the history of star formation. in galaxies.
Specifically, they are performing deep multiband imaging of three resolved star systems within one megaparsec (~3,260 light-years) of Earth using Webb’s Near Infrared Camera (NIRCam) and Imaging Slitless Spectrograph near infrared (NIRISS).
These include the globular cluster M92, the ultra-faint dwarf galaxy Draco II, and the star-forming dwarf galaxy WLM.
The population of low-mass stars in WLM makes it particularly interesting because they are long-lived, meaning some of the stars seen there today may have formed early in the Universe. .
“By determining the properties of these low-mass stars (like their age), we can gain insight into what happened in the very distant past,” McQuinn said.
“It’s very complementary to what we learn about early galaxy formation by looking at high redshift systems, where we see galaxies as they existed when they first formed.”
Another goal is to use the WLM dwarf galaxy to calibrate the JWST to ensure it can measure star brightness with extreme precision, which will allow astronomers to test models of stellar evolution in the near future. infrared.
McQuinn and his colleagues are also developing and testing non-proprietary software to measure the brightness of resolved stars imaged with the NIRCam, which will be made available to the public.
The results of their ESR project will be published before the Round 2 call for proposals (January 27, 2023).
The James Webb Space Telescope has been in space for less than a year but has already proven invaluable. The breathtaking views of the cosmos he provided include deep-field images, extremely precise observations of galaxies and nebulae, and detailed spectra of extrasolar planet atmospheres.
The scientific breakthroughs it has already enabled have been nothing short of revolutionary. Before the end of its planned 10-year mission (which could be extended to 20), truly game-changing breakthroughs are expected.
This article was originally published by Universe Today. Read the original article.
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