Hidden Stars Halfway Across the Universe: The Webb Telescope’s Stunning Discovery

Scitech Daily ^ | January 10, 2025 | Daniel Stolte, University of Arizona

[Red Badger]

In this zoomed-in detail of the Hubble image of Abell 370, the host galaxy where the 44 stars were discovered appears several times: in a normal image (left), and a distorted image appearing as a drawn-out smear of light. Credit: NASA

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Over 40 stars in a galaxy billions of light-years away were photographed, offering a glimpse into an era when the universe was only half as old as it is now.

Astronomers using the James Webb Space Telescope have accomplished a monumental feat in the field of astronomy by observing individual stars in a galaxy over 6.5 billion light-years away. This milestone, enabled by gravitational lensing and the telescope’s sensitivity, not only challenges previous observational limits but also opens new avenues for understanding the universe’s structure and the mysteries of dark matter.

Cosmic Breakthrough in Astronomy

Seeing individual stars halfway across the observable universe has long been thought impossible — like using binoculars to spot grains of dust on the moon. But an international team of astronomers, led by researchers at the University of Arizona’s Steward Observatory, achieved just that, thanks to a remarkable cosmic phenomenon.

Using NASA’s James Webb Space Telescope (JWST), the team observed a galaxy located nearly 6.5 billion light-years from Earth, from a time when the universe was just half its current age. In this distant galaxy, they identified a surprising number of individual stars, made visible through the combined effects of gravitational lensing — a natural magnification caused by massive objects bending light — and JWST’s exceptional light-collecting power.

Their findings, published on January 6 in Nature Astronomy, set a new record: the largest number of individual stars ever detected in the distant universe. This breakthrough also offers a new pathway to explore one of the cosmos’s greatest enigmas — dark matter.

Thanks to gravitational lensing, astronomers were able to directly image stars across the enormous distance of 6.5 billion light-years, highlighted by “crosshair” markings in this close-up image of Abell 370 taken with the James Webb Space Telescope. Credit: Yoshinobu Fudamoto/NASA

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Unveiling Distant Stars

Most galaxies, including our Milky Way, are home to tens of billions of stars. In nearby galaxies like Andromeda, astronomers can study stars individually. But in galaxies billions of light-years away, the stars blur together, their light traveling for eons before reaching us. This blending has posed a significant challenge for scientists seeking to understand how galaxies form and evolve.

“To us, galaxies that are very far away usually look like a diffuse, fuzzy blob,” said lead study author Yoshinobu Fudamoto, an assistant professor at Chiba University in Japan and a visiting scholar at Steward Observatory. “But actually, those blobs consist of many, many individual stars. We just can’t resolve them with our telescopes.”

Recent advances in astronomy have opened new possibilities by leveraging gravitational lensing – a natural magnification effect caused by the strong gravitational fields of massive objects. As predicted by Albert Einstein, gravitational lenses can amplify the light of distant stars by factors of hundreds or even thousands, making them detectable with sensitive instruments like JWST.

The massive, yet invisible halo of dark matter of a galaxy cluster works as a “macrolens,” while lone, unbound stars drifting through the cluster act as additional “microlenses, multiplying the factor of magnification. Credit: Yoshinobu Fudamoto

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Gravitational Lensing and the Dragon Arc

“These findings have typically been limited to just one or two stars per galaxy,” Fudamoto said. “To study stellar populations in a statistically meaningful way, we need many more observations of individual stars.”

Fengwu Sun, a former U of A graduate student who is now a postdoctoral scholar at the Center for Astrophysics | Harvard & Smithsonian, stumbled on a treasure trove of such stars when he was inspecting JWST images of a galaxy known as the Dragon Arc, located along the line of sight from Earth behind a massive cluster of galaxies called Abell 370. Due to its gravitational lensing effect, Abell 370 stretches the Dragon Arc’s signature spiral into an elongated shape – like a hall of mirrors of cosmic proportions.

In December 2022 and 2023, JWST obtained two pictures of the Dragon Arc. Within these images, astronomers counted 44 individual stars whose brightness changed over time due to variations in the gravitational lensing landscape.

“This groundbreaking discovery demonstrates, for the first time, that studying large numbers of individual stars in a distant galaxy is possible,” Sun said – as long as nature is there to lend a helping hand.

Abell 370, a galaxy cluster located nearly 4 billion light-years away from Earth features several arcs of light, including the “Dragon Arc” (lower left of center). These arcs are caused by gravitational lensing: Light from distant galaxies far behind the massive galaxy cluster coming toward Earth is bent around Abell 370 by its massive gravity, resulting in contorted images. Credit: NASA, ESA, R. Bouwens and G. Illingworth (University of California, Santa Cruz)

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Microlensing Reveals New Insights

However, even extremely strong gravitational magnification from a galaxy cluster is not sufficient to magnify individual stars in galaxies even farther away. In this case, the discovery was made possible by a serendipitous alignment of “lucky stars.”

“Inside the galaxy cluster, there are many stars floating around that are not bound by any galaxy,” said co-author Eiichi Egami, a research professor at Steward Observatory. “When one of them happens to pass in front of the background star in the distant galaxy along the line of sight with Earth, it acts as a microlens, in addition to the macrolensing effect of the galaxy cluster as a whole.”

The combined effects of macrolensing and microlensing dramatically increase the magnification factor, allowing JWST to pick up individual stars that otherwise would be too far and faint to be detected at all.

Because the stars inside the magnifying cluster move relative to the target stars in the distant galaxy and Earth, the alignment of microlenses in this natural “telescope” changes slightly over short timeframes – from a few days to a week. When they are perfectly aligned, the brightness and magnification of the distant stars increase dramatically, only to fade again shortly afterwards.

“By observing the same galaxy multiple times, we can spot stars in distant galaxies because they appear to pop in and out of existence,” Fudamoto said. “This is a result of the varying effective magnifications from the macro- and microlensing effect as the microlensing stars move in and out of the line of sight.”

The research team carefully analyzed colors of each of the stars inside the Dragon Arc and found that many are red supergiants, similar to Betelgeuse in the constellation of Orion, which is in the final stages of its life. This contrasts with earlier discoveries, which predominantly identified blue “supergiants” similar to Rigel and Deneb, which are among the brightest stars in the night sky. According to the researchers, this difference in stellar types also highlights the unique power of JWST observations at infrared wavelengths that could detect stars at lower temperatures.

Future JWST observations are expected to capture more magnified stars in the Dragon Arc galaxy. These efforts could lead to detailed studies of hundreds of stars in distant galaxies. Moreover, observations of individual stars could provide insight into the structure of gravitational lenses and even shed light on the elusive nature of dark matter.

Reference:

“Identification of more than 40 gravitationally magnified stars in a galaxy at redshift 0.725”

by Yoshinobu Fudamoto, Fengwu Sun, Jose M. Diego, Liang Dai, Masamune Oguri, Adi Zitrin, Erik Zackrisson, Mathilde Jauzac, David J. Lagattuta, Eiichi Egami, Edoardo Iani, Rogier A. Windhorst, Katsuya T. Abe, Franz Erik Bauer, Fuyan Bian, Rachana Bhatawdekar, Thomas J. Broadhurst, Zheng Cai, Chian-Chou Chen, Wenlei Chen, Seth H. Cohen, Christopher J. Conselice, Daniel Espada, Nicholas Foo, Brenda L. Frye, Seiji Fujimoto, Lukas J. Furtak, Miriam Golubchik, Tiger Yu-Yang Hsiao, Jean-Baptiste Jolly, Hiroki Kawai, Patrick L. Kelly, Anton M. Koekemoer, Kotaro Kohno, Vasily Kokorev, Mingyu Li, Zihao Li, Xiaojing Lin, Georgios E. Magdis, Ashish K. Meena, Anna Niemiec, Armin Nabizadeh, Johan Richard, Charles L. Steinhardt, Yunjing Wu, Yongda Zhu and Siwei Zou,

6 January 2025, Nature Astronomy.

DOI: 10.1038/s41550-024-02432-3

This project was supported by multiple funders including NASA and NSF.

[Red Badger]

James Webb Ping!....................

[Telepathic Intruder]

The focus of the sun’s gravitational bending of light is about 550 AU away. If they could get a probe there, the sun would act like the lens of a giant telescope. But that’s about triple the distance that Voyager 1, the farthest probe, has gotten in the last 50 years.

[Omnivore-Dan]

There is no beginning and there is no end. Unfathomable.

[wildcard_redneck]

I often wonder if ‘dark matter’ is really the interaction of our universe with other universes.

[kelly4c]

Yep. As a child, the thought of it blew my mind. Was raised in the church and thinking about the whole nature of God, the universe, and how if we are “saved” we will live forever and I was like what if I don’t want to live forever I didn’t even ask to be born! Lol.

[rktman]

Now you got my little pea brain going. Dang it! 😊👍

[hecticskeptic]

The first seven verses of the great book of Job 38 that just touches on the greatness of the Creator and juxtaposes that to puny mankind...

Then the Lord answered Job out of the whirlwind, and said,

2 Who is this that darkeneth counsel by words without knowledge?

3 Gird up now thy loins like a man; for I will demand of thee, and answer thou me.

4 Where wast thou when I laid the foundations of the earth? declare, if thou hast understanding.

5 Who hath laid the measures thereof, if thou knowest? or who hath stretched the line upon it?

6 Whereupon are the foundations thereof fastened? or who laid the corner stone thereof;

7 When the morning stars sang together, and all the sons of God shouted for joy?

.....

[Red Badger]

[enumerated]

When will they come up with a telescope that can see straight?

[NativeSon]

with matter & energy "out of phase" with our universe ?
We could "see" the effect but not the source.

The things that keep me up at night...

[wildcard_redneck]

Astronomers, astrophysicists and governments love to cling to theories annd beliefs until new evidence absolutely proves them wrong and even then it can take decades for them to be accepted. We only need to look back in history to see how hard the scientific and cultural establishment fought the idea of a heliocentric solar system where the Earth orbits the Sun. They imprisoned and burned people alive over it.

Here is some reading on the topic: https://www.wired.com/2012/06/famous-persecuted-scientists/

[Getready]

Finally discovered dark matter, eh?

[Red Badger]

Nope. Doesn’t exist.......

[wildcard_redneck]

"There is no beginning and there is no end. Unfathomable."

I believe that the universe is eternal. It goes through phases but it always returns to the beginning, starting again, and never ending.

The scientific theory of the Big Bang is that the universe came in into being from nothing and rapidly expanded. And just what would stop that from happening again and again and again endlessly, and with countless universes?

[Getready]

They might discover enough “hidden stars” to balance out their “missing mass” problem. Doubt it....

[Getready]

“nothing” would stop it.

[Getready]

Known as the oscillating universe hypotheses....
Terms like “eternal” and “beginning” are metaphysical terms..No human, as far as we know, was there to recount the beginning” and “eternity” can never occur cause there’s always just one more measurement of time...if no extra time, then there is no eternal. It’s then called “the end”
Is the best our science can come up with is this: “Nothing made Everything”?
IMHO
Freegards.

[wildcard_redneck]

Reality and the universe is eternal.

[SuperLuminal]

Excellent...