This webpage was generated programmatically. To view the article in its primary source, you can follow the link below:
https://phys.org/news/2025-01-treasure-trove-unseen-stars-dragon.html
and should you wish to have this article removed from our website, please reach out to us
Attempting to view individual stars halfway across the observable universe is deemed an impossibility in astronomy, akin to lifting a pair of binoculars towards the moon in hopes of identifying distinct particles of dust within its craters. Nevertheless, due to a cosmic anomaly, an international consortium of astronomers accomplished just that.
Utilizing NASA’s James Webb Space Telescope (JWST), postdoctoral scholar Fengwu Sun at the Center for Astrophysics | Harvard & Smithsonian (CfA) and his group scrutinized a galaxy nearly 6.5 billion light-years from Earth, at a time when the universe was half its present age. Within this remote galaxy, the team discerned 44 distinct stars, visible due to an effect referred to as gravitational lensing and JWST’s exceptional light-gathering abilities.
Published in the journal Nature Astronomy, this discovery represents a remarkable achievement—the highest number of individual stars identified in the far-off universe. It also opens a pathway to explore one of the universe’s most significant enigmas—dark matter.
“This pioneering discovery illustrates, for the first time, that investigating large quantities of individual stars in a distant galaxy is achievable,” stated Sun, a co-author of the study.
“Whereas earlier research using the Hubble Space Telescope identified around seven stars, our capabilities now allow us to resolve stars that were previously beyond our reach. Crucially, observing a higher number of individual stars will enhance our understanding of dark matter within the lensing plane of these galaxies and stars, something we were unable to accomplish with only the limited number of stars previously observed.”
CfA’s Sun discovered this wealth of stars through an examination of JWST images focused on a galaxy known as the Dragon Arc, positioned along the line of sight from Earth behind a significant cluster of galaxies called Abell 370. Due to its gravitational lensing characteristics, Abell 370 elongates the Dragon Arc’s recognizable spiral into an extended form—akin to a hall of mirrors of cosmic extent.
The research team meticulously examined the colors of each star within the Dragon Arc, revealing that many are red supergiants, comparable to Betelgeuse in the constellation Orion, which is nearing the end of its life. This contrasts with prior findings, which mainly located blue “supergiants” similar to Rigel and Deneb, some of the brightest stars visible in the night sky.
According to the researchers, this disparity in stellar classifications underscores the distinctive capability of JWST observations at infrared wavelengths, capable of uncovering stars at lower temperatures.
“During our search for individual stars, our primary goal was to find a background galaxy being lensing-magnified by the galaxies within this massive cluster,” explained Sun. “However, upon processing the data, we recognized what seemed to be numerous individual star points. It was an exhilarating discovery as it marked the first time we had the opportunity to observe so many individual stars at such great distances.”
In this close-up aspect of the Hubble capture of Abell 370, the main galaxy where the 44 stars were identified appears multiple times: in a standard image (left), and a warped image that looks like an elongated blur of light. Credit: NASA
Sun, in particular, is thrilled about the upcoming chance to examine these red supergiants.
“We possess more knowledge about red supergiants in our immediate galactic vicinity because they are nearer, allowing us to obtain clearer images and spectra, and in some instances, even resolve the stars. We can apply the insights we’ve acquired from investigating red supergiants in the local cosmos to comprehend their subsequent behavior during such an early stage of galaxy formation in future research.”
The majority of galaxies, including the Milky Way, harbor tens of billions of stars. In proximate galaxies such as Andromeda, astronomers can monitor stars individually. Nevertheless, in galaxies that are billions of light-years away, stars seem intertwined as their light must travel through billions of light-years before reaching us, presenting a long-standing hurdle for scientists studying the formation and evolution of galaxies.
“To us, galaxies that are incredibly distant typically appear as a vague, fuzzy mass,” stated lead study author Yoshinobu Fudamoto, an assistant professor at Chiba University in Japan. “However, those masses are actually composed of numerous individual stars. We simply cannot resolve them using our telescopes.”
Recent advancements in astronomy have unveiled new opportunities by utilizing gravitational lensing—a natural amplification phenomenon initiated by the intense gravitational fields of massive entities. As anticipated by Albert Einstein, gravitational lenses can enhance the light of remote stars by factors of hundreds or even thousands, enabling them to be detected with sensitive instruments like JWST.
“These discoveries have typically been restricted to just one or two stars per galaxy,” Fudamoto remarked. “To examine stellar populations in a statistically significant manner, we require many more observations of individual stars.”
Future JWST observations are anticipated to capture more amplified stars in the Dragon Arc galaxy. These initiatives could facilitate detailed analyses of hundreds of stars in distant galaxies. Additionally, the study of individual stars could offer insights into the framework of gravitational lenses and may even illuminate the enigmatic nature of dark matter.
Additional information:
Yoshinobu Fudamoto et al, Identification of more than 40 gravitationally magnified stars in a galaxy at redshift 0.725, Nature Astronomy (2025). DOI: 10.1038/s41550-024-02432-3
Citation:
A treasure trove of unseen stars beyond the ‘Dragon Arc’ (2025, January 6)
retrieved 6 January 2025
from
This document is protected by copyright. Excluding any fair dealing for the purpose of private study or research, no
part may be reproduced without written consent. The content is provided for informational purposes only.
This page was generated programmatically, to read the article in its original location you can follow the link below:
https://phys.org/news/2025-01-treasure-trove-unseen-stars-dragon.html
and if you wish to remove this article from our site please contact us
This webpage was generated automatically; to view the article in its initial setting, you can…
This webpage was generated automatically, to view the article at its original source you can…
This page was generated programmatically; to view the article in its source location, please visit…
This page was generated automatically, to access the article in its initial location please visit…
This page was generated automatically; to read the article in its initial location, you may…
This page has been generated automatically. To view the article at its original source, you…