Tag Archives: Globular

Hubble Explores 13 Billion-Year-Old Globular Cluster: Insights from the Universe’s Ancient Treasures

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Astronomers employing the NASA/ESA Hubble Space Telescope have obtained a stunning image of NGC 6426, an ancient globular star cluster located in the outer halo of the Milky Way galaxy. This remarkable object contains two distinct generations of stars, serving as a cosmic time capsule from an era when the universe was still forming its heaviest elements.

This Hubble image showcases the globular cluster NGC 6426 located about 67,000 light-years away in the constellation Ophiuchus. Image credits: NASA / ESA / A. Dotter, Dartmouth College / Gladys Kober, NASA and The Catholic University of America.

NGC 6426 is situated approximately 67,000 light-years from Earth, at the celestial equator within the constellation Ophiuchus.

This globular cluster, also referred to as C 1742+031 or GCl 76, was discovered by German-British astronomer William Herschel on June 3, 1786.

Estimated to be around 13 billion years old, NGC 6426 formed only a few hundred million years after the Big Bang. Given that the universe is about 13.8 billion years old, this cluster encapsulates evidence of conditions that existed in the early universe.

Unlike many clusters, NGC 6426 traverses the sparse outer halo of the Milky Way rather than orbiting within the galaxy’s disk.

Initially thought to consist solely of contemporaneous stars, advanced high-resolution spectroscopy has revealed that NGC 6426 may harbor two distinct generations of stars.

“NGC 6426 is a collection of globular stars bound by their mutual gravity and ranks among the 150 known globular clusters in the Milky Way,” Hubble astronomers stated.

“These star groups are believed to have formed from the same collapsing gas cloud, often resulting in stars of similar ages. Stars in globular clusters are generally quite old.”

“At approximately 13 billion years old, NGC 6426 ranks as one of the oldest globular clusters in the Milky Way, almost as ancient as the universe itself.”

Astronomers utilized the Hubble Telescope to capture images of NGC 6426 as part of their research on globular star clusters within the Milky Way halo.

“In this image, blue represents shorter wavelengths of visible light, while red signifies longer wavelengths and some near-infrared light,” they explained.

“The colors in Hubble images are processed to accurately depict the wavelengths of light that pass through the sensors used during observations.”

“There exists a direct relationship between a star’s color and its temperature; hence, the blue stars in this image are hotter compared to the cooler red stars.”

The stars in NGC 6426 exhibit low metallicity, indicating a scarcity of elements heavier than hydrogen or helium.

“These conditions mirror those of the early universe, a time when matter predominantly consisted of helium and hydrogen, with heavier elements beginning to emerge through nuclear fusion within massive stars.”

Source: www.sci.news

Discovering Four Generations of Stars in the Globular Cluster Tarzan 5: A Breakthrough by Astronomers

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Globular clusters are traditionally known to host a single, ancient population of stars. However, groundbreaking data from the NASA/ESA/CSA James Webb Space Telescope and the NASA/ESA Hubble Space Telescope has confirmed the presence of two distinct star populations within the ancient star system Terzan 5. Once classified merely as a globular cluster, Terzan 5 now also shows evidence of two recent rounds of star formation.

This Webb/NIRCam image showcases the star cluster Terzan 5. Image credit: NASA/ESA/CSA/Webb.

Terzan 5, discovered in 1968 by Armenian-Turkish-French astronomer Agop Terzan, is located approximately 19,000 light-years away in the constellation Sagittarius.

Also known as ESO 520-27 and 2MASX J17480455-2446441, this star system is home to hundreds of thousands of varied stars.

Nesting within the inner bulge of the Milky Way, Terzan 5 exhibits many characteristics reminiscent of globular clusters, yet significant findings emerged in 2009 revealing two distinct star populations.

A 2016 study using Hubble provided crucial age estimates: one population formed around 12 billion years ago, pre-dating the Milky Way, while the other emerged approximately 5 billion years ago, shortly before Earth’s formation. This complex history suggests Terzan 5’s evolution diverges from typical globular clusters.

Dr. Giorgia Zullo, a student at the University of Bologna, remarked, “Webb’s new near-infrared observations, in conjunction with Hubble’s archival data, present a clearer narrative of Terzan 5’s history.”

Studying Terzan 5 presents challenges due to its dense star environment and substantial dust cover within the galaxy.

Webb’s infrared capabilities enable astronomers to penetrate this dust, allowing for a comprehensive cataloging of both faint and distant stars.

By analyzing the colors and brightness of the stars, researchers can categorize them based on different ages and chemical compositions.

Webb successfully measured these essential properties for all visible stars, including those in Terzan 5 and unrelated foreground stars.

To distinguish Terzan 5’s stars, researchers leveraged Hubble’s long-term observations. The varying intervals between Hubble’s 12-year exposures allowed them to track tiny stellar movements, known as proper motion, helping to identify which stars are part of Terzan 5 versus those belonging to the Milky Way’s bulge.

By integrating findings from both Webb and Hubble, researchers found compelling evidence for two additional stellar populations, one dating back 3.8 billion years and another 2.5 billion years old.

They also determined the ages of the known stellar populations with remarkable precision, revealing formation timelines between 12.5 billion and 4.7 billion years ago.

The existence of these four distinct generations of stars suggests that Terzan 5 likely interacted with another celestial object, potentially a globular cluster or giant molecular cloud, enriching it with gas and dust to spark a second round of star formation.

Observations made using the W.M. Keck Observatory and ESO’s Very Large Telescope indicate that Terzan 5 hosts a unique stellar population.

Dr. R. Michael Rich, an astronomer at UCLA, noted, “As these populations age, the clusters preserve a fossil record of progressive heavy element enrichment from supernovae.”

Terzan 5 has managed to retain essential raw materials, allowing for the formation of multiple star generations.

There is substantial evidence that Terzan 5 witnessed a powerful supernova explosion that produced heavier elements, which were subsequently dispersed amongst the following generations of stars.

In less massive systems, the explosive force could have expelled residual gases and dust, thereby releasing the resultant elements.

Terzan 5’s progenitor possessed enough mass to sustain ejection, enabling new star generations to take shape over billions of years.

The results indicate that Terzan 5 likely remains from a significantly larger star system that formed around 12.5 billion years ago.

This cluster is remarkable in its survival without merging or fully blending with the Milky Way’s bulge.

Professor Francesco Ferraro from the University of Bologna explains, “For some reason, this extraordinary cluster formed separately from the bulge and was not obliterated during the bulge’s formation.”

“Terzan 5 is considered a bulge fossil fragment, resembling the primordial mass that contributed to bulge formation.”

For further details, consult this study published in Astronomy and Astrophysics.

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G. Zullo et al. 2026. Terzan 5’s multi-age stellar population revealed by JWST. A&A 709, A212; doi: 10.1051/0004-6361/202659349

Source: www.sci.news

Astronomers find intermediate-mass black hole in largest globular cluster in Milky Way

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Using more than 500 images from the NASA/ESA Hubble Space Telescope, astronomers have found evidence of a 20,000-solar-mass black hole at the center of Earth. Omega CentauriIt is a globular cluster located in the constellation Centaurus, 5,430 parsecs (17,710 light years) from the Sun.

Omega Centauri is about 10 times more massive than other large globular clusters. Image credit: NASA / ESA / Hubble / Maximilian Häberle, MPIA.

Astronomers know that stellar-mass black holes (black holes with masses between 10 and 100 times that of the Sun) are the remnants of dying stars, and that supermassive black holes, with masses more than a million times that of the Sun, exist at the center of most galaxies.

But the universe is littered with what appear to be more mysterious types of black holes.

These intermediate-mass black holes, with masses between 100 and 10,000 times that of the Sun, are so difficult to measure that their very existence is sometimes debated.

Only a few intermediate-mass black hole candidates have been discovered so far.

Determining the black hole population is an important step towards understanding the formation of supermassive black holes in the early universe.

“Omega Centauri is a special example among globular clusters in the Milky Way,” said astronomer Maximilian Höberle of the Max Planck Institute for Astronomy and his colleagues.

“Omega Centauri is widely accepted to be the stripped core of an accreted dwarf galaxy due to its high mass, complex stellar population and kinematics.”

“These factors, combined with its proximity, make the planet a prime target in the search for intermediate-mass black holes.”

Omega Centauri is made up of about 10 million stars, making it about 10 times more massive than any other large globular cluster.

In the study, the authors measured the velocities of 1.4 million stars from images of the cluster taken by the Hubble Space Telescope.

Although most of these observations were intended for calibration of Hubble's instruments rather than for scientific use, they proved to be an ideal database for the team's research activities.

“We looked for fast-moving stars that are expected to be near concentrated masses such as black holes,” said astronomer Holger Baumgart of the University of Queensland.

“Identifying these stars was the smoking gun we needed to prove the existence of black holes, and we've done just that.”

“We found seven stars that shouldn't be there,” Dr Hebel said.

“They're moving so fast that they're likely to escape the herd and never come back.”

“The most likely explanation is that a very massive object is gravitationally tugging on these stars, keeping them near the center.”

“The only objects this massive are black holes, which have a mass at least 8,200 times that of the Sun.”

“This discovery is the most direct evidence to date for the presence of an intermediate-mass black hole at Omega Centauri,” said Dr Nadine Neumayer, an astronomer at the Max Planck Institute for Astronomy.

“This is extremely exciting because very few other black holes with similar masses are known.”

“The black hole at Omega Centauri may be the best example of an intermediate-mass black hole in our cosmic neighborhood.”

Team paper Published in the journal Nature.

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M. Heberle others2024. Stars moving at high speed around the intermediate-mass black hole at Omega Centauri. Nature 631, 285-288; Source: 10.1038/s41586-024-07511-z

Source: www.sci.news

Hubble Observes Large Globular Cluster in Large Magellanic Cloud

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Astronomers using the NASA/ESA Hubble Space Telescope have captured detailed images of the globular star cluster NGC 1651 in the constellation Mensa.

This Hubble image shows the globular cluster NGC 1651 about 162,000 light-years away in the constellation Mensa. Image credits: NASA / ESA / Hubble / L. Girardi / F. Niederhofer.

Globular clusters are densely packed spherical clusters of hundreds of thousands or even millions of stars.

They are among the oldest known objects in the universe and are preferentially associated with the oldest components of galaxies.

There are at least 150 such objects in our Milky Way, and several more may be hidden behind the galaxy's thick disk.

NGC1651 is part of the Large Magellanic Cloud, the largest and brightest of the Milky Way's satellite galaxies.

beginning discovered Discovered by British astronomer John Herschel on November 3, 1834, this globular cluster is located approximately 162,000 light-years away in the constellation Mensa.

NGC 1651, also known as ESO 55-30 or LW 12, has a diameter of 120 light years.

“A remarkable feature of this image is that NGC 1651 nearly fills the entire image, even though the globular cluster is only about 10 to 300 light-years in diameter,” Hubble astronomers said. Masu.

“In contrast, there are many Hubble images that feature entire galaxies, tens or even hundreds of millions of light-years in diameter, that more or less fill the entire image.”

Color images of NGC 1651 consist of observations from. Hubble's Wide Field Camera 3 Found in the near-infrared and optical portions of the spectrum.

“A common misconception is that Hubble and other large telescopes can observe objects of vastly different sizes by zooming in, much like we would with special cameras on Earth,” the astronomers said. Ta.

“However, while smaller telescopes may have the option to zoom in and out to some extent, larger telescopes do not.”

“Each telescope instrument has a fixed 'field of view' (the size of the area of the sky that can be observed in a single observation).”

“For example, WFC3's ultraviolet/visible light channel, the channel and instrument used to collect the data used in this image, has a field of view that is approximately one-twelfth the diameter of the moon as seen from Earth. Masu.”

“Every time WFC3 makes an observation, it becomes the size of the region of sky it can observe.”

“There are two reasons why Hubble is able to observe objects with such widely different sizes,” the researchers said.

“First, the distance to an object determines how big that object appears from Earth, so an entire galaxy that is relatively far away is compared to a relatively nearby globular cluster like NGC 1651. could take up the same amount of space as the sky.''

“In fact, a distant spiral galaxy lurks just to the left of the cluster in this image. It's undoubtedly much larger than the cluster, but here it appears small enough to blend in with the foreground stars.”

“Second, multiple images across different parts of the sky can be mosaicked to create a single image of an object too large for Hubble's field of view.”

Source: www.sci.news

Hubble Observes NGC 1841 Globular Cluster

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This new image from the NASA/ESA Hubble Space Telescope shows the globular star cluster NGC 1841 in the Large Magellanic Cloud.

This Hubble image shows the globular cluster NGC 1841 about 162,000 light-years away in the constellation Mensa. The color images include ultraviolet, optical, and near-infrared observations from both Hubble's Wide Field Camera 3 (WFC3) and Survey Altitude Camera (ACS). Three filters were used to sample different wavelengths. Color is obtained by assigning different hues to each monochromatic image associated with an individual filter. Image credits: NASA / ESA / Hubble / A. Saragedini / F. Niederhofer.

NGC1841 It is located approximately 162,000 light years away in the constellation Mensa.

The cluster is discovered It was proposed by British astronomer John Herschel on January 19, 1836.

Also known as ESO 4-15, this galaxy is part of the Large Magellanic Cloud, a satellite galaxy of our Milky Way.

“Satellite galaxies are galaxies that are gravitationally bound in orbit around a larger host galaxy,” Hubble astronomers said in a statement.

“While we usually think of our galaxy's closest galactic companion as the Andromeda galaxy, it would be more accurate to say that the Andromeda galaxy is the closest galaxy that does not orbit the Milky Way.”

“In fact, our galaxy is orbited by dozens of known satellite galaxies much closer than Andromeda, the largest and brightest of which is the Large Magellanic Cloud, which is easily visible to the naked eye even from the southern hemisphere. can.”

Globular clusters, such as NGC 1841, are very old systems of stars bound together by gravity into a single structure about 100 to 200 light-years in diameter.

These objects contain hundreds of thousands, or perhaps millions, of stars. The large mass in the cluster's rich stellar center pulls the stars inward, forming a star ball.

These are among the oldest objects known in the universe, relics from the earliest era of galaxy formation.

It is believed that all galaxies contain globular clusters. There are at least 150 such objects in our Milky Way galaxy.

“There are many globular star clusters in the Large Magellanic Cloud,” the astronomers said.

“These objects lie somewhere between open clusters (much less dense and tightly bound) and small, compact galaxies.”

“Increasingly sophisticated observations have revealed that the stellar populations and other characteristics of globular clusters are diverse and complex, but how these dense clusters form is poorly understood. yeah.”

“But all globular clusters have a certain consistency. They are so stable that they can persist for long periods of time, and therefore can be very old.”

“This means that globular clusters often contain large numbers of very old stars, making them similar to 'fossils' in the sky.”

“Just as fossils provide insight into the early development of life on Earth, globular clusters like NGC 1841 provide insight into the very early formation of stars in galaxies.”

Source: www.sci.news