The James Webb Space Telescope Early Release Science (ERS) program – first released on July 12, 2022 – has proven to be a treasure trove of science discoveries and breakthroughs.
Among the many areas of research may be the study of Resolved Stellar Populations (RSTs), which was the subject of ERS 1334.
There we are talking about large groups of stars, so that individual stars can be distinguished, but they are so far apart that many of them can be seen at the same time. A good example is the Wolf-Lundmark-Melotte (WLM) dwarf galaxy that borders the Milky Way.
Kristen McQuinn, an assistant professor of astrophysics at Rutgers University, is one of the Webb ERS program lead scientists whose work is focused on RSTs. Recently, Natasha Piro, a NASA senior communications specialist, spoke about how JWST has enabled new WLM studies.
Webb’s improved observations have shown that this galaxy is not connected to other galaxies in the past.
According to McQuinn, this makes astronomers a great candidate to test theories of galaxy formation and evolution. Here are the highlights of that interview.
WLM is about 3 million light-years from Earth, which means it’s pretty close (in astronomical terms) to the Milky Way. However, it is also relatively isolated, leading astronomers to conclude that it does not interact with other systems in the past.
When astronomers observed other nearby dwarf galaxies, they noticed that they were embedded in the Milky Way, indicating that they were in the process of merging.
It is all the more difficult to study because their mass of stars and vapor clouds cannot be fully distinguished from ours.
frameborder=”0″ allow=”accelerometer; autoplay clipboard-write; encrypted media; gyroscope; picture-in-picture” allowfullscreen>
Another important thing about WLM is that it is heavy in terms of elements heavier than hydrogen and helium (which existed in the early universe). Elements such as carbon, oxygen, silicon, and iron were formed in the cores of early star populations and dispersed when these stars exploded into supernovae.
In the case of WLM, which has experienced star formation throughout its history, the force of those explosions pushed these elements beyond time. This process is known as “galactic winds” and has been observed with small and low-mass galaxies.
Webb’s new images provide the clearest view of WLM ever seen. Earlier, the dwarf galaxy was imaged by the Infrared Array Camera (IAC) on the Spitzer Space Telescope (SST).
These are of limited resolution compared to Webb’s images, which can be seen in side-by-side comparison (shown below).
As you can see, Webb’s advanced infrared optics and instrumentation provide a much deeper view that allows individual stars and features to be distinguished. As McQuinn described it;
“We see myriads of individual stars of different colors, sizes, temperatures, ages, stages of evolution, interesting gas nebula clouds within the galaxy, foreground stars with Webb’s key diffraction, and galaxy colors with subtle features like tidal tails. It’s a really gorgeous picture.”
As McQuinn explained, the main science focus of ERS 1334 is to build on previous expertise with Spitzer, Hubble, and other space telescopes to learn more about the history of star formation in galaxies.
Specifically, they are making deep multi-band images of three star systems resolved within Megaparsec (~3,260 light-years) from Earth using the Webb Near-Infrared Camera (NIRCam) and the Near-Infrared Imaging Slitless Spectrograph (NIRISS).
These include the globular cluster M92, the dwarf galaxy Draco II, and the star-forming galaxy WLM.
The abundance of low-mass stars in the WLM makes it particularly interesting since they are so long-lived, which means that some of the stars seen today in the universe formed early.
“By determining the properties of these lower-mass stars (such as their ages), we can gain insight into what was happening in the distant past,” said McQuinn.
“It’s very complementary to what we’re learning about the early formation of galaxies by looking at high redshift systems, where we see galaxies when they first formed.”
Another goal is to use the WLM dwarf galaxy to calibrate JWST so that the brightness of stars can be measured with the highest accuracy, which will allow astronomers to explore patterns of star evolution in the near-infrared.
McQuinn and his colleagues are also developing and testing non-proprietary software to measure the brightness of high-resolution star images with NIRCam, which will be publicly available.
The results of their ESR initiative will be released before the Cycle II Program (January 27, 2023).
The James Webb Space Telescope has been around for less than a year but has already proven itself to be valuable. Breathtaking views of the cosmos, including deep-field images, extremely detailed observations of galaxies and nebulae, and detailed spectra from the atmospheres of extrasolar planets.
Scientific disintegrations have already been allowed to break down nothing less. Before his proposed 10-year mission (which could be extended to 20), some real paradigm-changing breakthroughs are anticipated.
This article was first published by Universe Today. Read the original article.
#Webb #stunning #unique #Dwarf #Galaxy