The James Webb Space Telescope Early Release Science (ERS) program – first broadcast on July 12, 2022 – has proven to be a treasure trove of scientific findings and achievements.
Among the many areas of research it enables is the study of Resolved Stellar Populations (RSTs), which is its subject. ERS 1334.
This refers to large groups of stars that are close enough to distinguish individual stars, but far enough away that multiple telescopes can capture them. It is a good example Wolf-Lundmark-Melotte (WLM) A dwarf galaxy neighboring the Milky Way.
Kristen McQuinn, professor of astrophysics at Rutgers University, is one of the lead scientists of the Webb ERS program, whose work focuses on RSTs. Recently, Natasha talked to PiroNASA’s senior communications officer on how JWST is enabling new WLM research.
Webb’s advanced 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. We present the main points of that interview.
Regarding WLM
The WLM is about 3 million light-years from Earth, which means it’s fairly close to the Milky Way (astronomically speaking). However, it is also relatively isolated, and astronomers have concluded that it has not interacted with other systems in the past.
When astronomers observed other nearby dwarf galaxies, they found that they were usually mixed with the Milky Way, indicating that they were in the process of merging.
This makes them difficult to study because their star and gas clouds are indistinguishable from ours.
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Another important thing about the WLM is that it is low in elements heavier than hydrogen and helium (common in the early Universe). Elements such as carbon, oxygen, silicon and iron formed in the cores of early population stars and were destroyed when these stars exploded in supernovae.
In the case of the WLM, which has experienced star formation throughout its history, the force of these explosions pushed 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 the WLM ever seen. Previously, an image of a dwarf galaxy Infrared Array Camera (IAC) on Spitzer Space Telescope (SST).
These provided limited resolution compared to the Webb images, which can be seen in a side-by-side comparison (shown below).
As you can see, Webb’s infrared optics and advanced instrumentation provide a deeper view, allowing individual stars and features to be distinguished. As McQuinn describes it:
“We can see countless individual stars of different colors, sizes, temperatures, ages, and evolutionary stages; interesting nebulous gas clouds in the galaxy; foreground stars with Webb diffraction spikes; and background galaxies with neat features like tidal tails. This It’s really a great sight.”
ERS Program
As McQuinn explained, the main scientific focus of ERS 1334 is to build on previous experience with Spitzer, Hubble and other space telescopes to learn more about the star formation history of galaxies.
In particular, they are conducting a deep multiband image of three star systems resolved within Megaparsecs (~3,260 light-years) of Earth with the help of Webb. Near Infrared Camera (NIRCam) and A near-infrared imaging slitless spectrograph (NIRISS).
These include the global cluster M92ultra faint dwarf galaxy Draco IIand the star-forming WLM dwarf galaxy.
The population of low-mass stars in the WLM makes it particularly interesting because they are very long-lived, meaning that some of the stars seen there today may have formed early in the Universe.
“By determining the properties (such as their ages) of these low-mass stars, we can gain insight into what happened in the very distant past,” McQuinn said.
“This greatly complements what we have learned about the early formation of galaxies high redshift systemsHere we see galaxies as they existed when they first formed.”
Another goal is to use the WLM dwarf galaxy to calibrate JWST to ensure that it can measure the brightness of stars with extreme precision, which will allow astronomers to test models of stellar evolution in the near-infrared.
McQuinn and his colleagues are also developing and testing non-proprietary software to measure the brightness of resolved stars imaged with NIRCam, which will be released to the public.
The results of their ESR project will be announced before the Cycle 2 Call for Proposals (January 27, 2023).
The James Webb Space Telescope has been in space for less than a year, but it has already proven itself to be invaluable. The stunning views of space it provides include deep-field images, extremely precise observations of galaxies and nebulae, and detailed spectra of extrasolar planetary atmospheres.
The scientific achievements he already allowed were nothing short of groundbreaking. Before the end of its planned 10-year mission (which could be extended to 20), some truly paradigm-shifting advances are expected.
This article was originally published by Universe today. read it original article.
