Webb gives us a stunning new look at this lonely dwarf galaxy

(ORDO NEWS) — The James Webb Space Telescope (ERS) Early Release Program, first released on July 12, 2022, has proven to be a mine of scientific discoveries and breakthroughs.

Among the many research areas it allows is the Resolved Star Populations (RST) study, which was the subject of ERS 1334.

This refers to large groups of stars that are close enough that individual stars can be distinguished, but far enough apart that telescopes can capture many of them at once.

A good example is the Wolf-Lundmark-Melotta (WLM) dwarf galaxy, neighboring the Milky Way.

Kristen McQuinn, assistant professor of astrophysics at Rutgers University, is one of the lead scientists at Webb ERS. a program whose work is focused on RST.

She recently spoke with Natasha Piro, NASA Senior Communications Officer, about how JWST enabled new WLM research.

Webb’s improved observations showed that this galaxy did not interact with other galaxies in the past.

This makes astronomers an excellent candidate for testing theories of galaxy formation and evolution, McQuinn says. Here are the highlights of this interview.

About WLM

The 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, which has led 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 tend to be entangled with the Milky Way, indicating that they are in the process of merging.

This makes them difficult to study, as their population of stars and gas clouds cannot be completely distinguished from ours.

Another important feature of the WLM is that it has few 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 dissipated when those stars exploded as supernovae.

In the case of the WLM, which has experienced star formation throughout its history, the force of these explosions has driven these elements out over time.

This process is known as “galactic winds” and has been observed in small, low-mass galaxies.

JWST images

Webb’s new images provide the clearest view of the WLM ever seen. The dwarf galaxy was previously imaged by the Infrared Camera (IAC) on the Spitzer Space Telescope (SST).

They provided limited resolution compared to the images of Webb seen from the side. -side comparison (shown below).

Webb gives us a stunning new look at this lonely dwarf galaxy
Part of the Wolf-Lundmark-Melotte (WLM) dwarf galaxy captured by the Spitzer Space Telescope’s infrared camera (left) and the James Webb Space Telescope’s near-infrared camera (right)

As you can see, Webb infrared optics and an advanced set of tools provide a much deeper view that allows you to distinguish between individual stars and features. As McQuinn described it:

“We can see myriads of individual stars of different colors, sizes, temperatures, ages and stages of evolution; interesting clouds of nebular gas within the galaxy; foreground stars with Webb diffraction. peaks; and background galaxies with neat features such as tidal tails. It’s a really great image.”

ERS Program

As McQuinn explained, the main scientific goal of ERS 1334 is to build on previous experience from the Spitzer, Hubble and others space telescopes to learn more about the history of star formation in galaxies.

In particular, they conduct deep multichannel imaging of three resolved star systems within a megaparsec. (~3260 light-years) of the Earth using the Webb Near Infrared Camera (NIRCam) and the Near Infrared Slitless Spectrograph (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 the WLM makes it particularly interesting as they are very long-lived, meaning that some of the stars visible there today may have formed during the early universe.

“By determining the properties of these low-mass stars (such as their ages), we can get an idea of ​​what happened in the very distant past,” McQuinn said.

“This is very complementary to what we are learning about early galaxy formation by studying high redshift systems, where we see galaxies as they were when they first formed.”

Another goal is to use the WLM dwarf galaxy to calibrate the JWST to make sure it can measure the brightness of stars with extreme accuracy, allowing astronomers to test models of stellar evolution in the near infrared.

McQuinn and her colleagues are also developing and testing non-proprietary NIRCam resolved star brightness measurement software that will be made available to the public.

The results of their ESR project will be made public d prior to the call for proposals for the second cycle (January 27, 2023).

The James Webb Space Telescope has been in space for less than a year, but has already proven to be invaluable.

The breathtaking views of space he has provided include deep field images, extremely accurate observations of galaxies and nebulae, and detailed spectra of extrasolar planets’ atmospheres.

The scientific breakthroughs he had already made were nothing short of groundbreaking. Before the completion of the planned 10-year mission (which can be extended to 20 years), some truly revolutionary breakthroughs are expected.

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