Alleviating the Hubble tension with Torsion Condensation (TorC)
Alleviating the Hubble tension with Torsion Condensation (TorC)
All-sky radio telescopes ditch the dish
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Nature, Published online: 24 July 2025; doi:10.1038/d41586-025-01230-9
New Canary Islands home could save controversial Thirty Meter Telescope first proposed for Hawaii.NASA’s Hubble, Chandra Spot Rare Type of Black Hole Eating a Star
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NASA, ESA, CXC, Yi-Chi Chang (National Tsing Hua University); Image Processing: Joseph DePasquale (STScI)
NASA’s Hubble Space Telescope and NASA’s Chandra X-ray Observatory have teamed up to identify a new possible example of a rare class of black holes. Called NGC 6099 HLX-1, this bright X-ray source seems to reside in a compact star cluster in a giant elliptical galaxy.
Just a few years after its 1990 launch, Hubble discovered that galaxies throughout the universe can contain supermassive black holes at their centers weighing millions or billions of times the mass of our Sun. In addition, galaxies also contain as many as millions of small black holes weighing less than 100 times the mass of the Sun. These form when massive stars reach the end of their lives.
Far more elusive are intermediate-mass black holes (IMBHs), weighing between a few hundred to a few 100,000 times the mass of our Sun. This not-too-big, not-too-small category of black holes is often invisible to us because IMBHs don’t gobble as much gas and stars as the supermassive ones, which would emit powerful radiation. They have to be caught in the act of foraging in order to be found. When they occasionally devour a hapless bypassing star — in what astronomers call a tidal disruption event— they pour out a gusher of radiation.
The newest probable IMBH, caught snacking in telescope data, is located on the galaxy NGC 6099’s outskirts at approximately 40,000 light-years from the galaxy’s center, as described in a new study in the Astrophysical Journal. The galaxy is located about 450 million light-years away in the constellation Hercules.
A Hubble Space Telescope image of a pair of galaxies: NGC 6099 (lower left) and NGC 6098 (upper right). The purple blob depicts X-ray emission from a compact star cluster. The X-rays are produced by an intermediate-mass black hole tearing apart a star. Science: NASA, ESA, CXC, Yi-Chi Chang (National Tsing Hua University); Image Processing: Joseph DePasquale (STScI)Astronomers first saw an unusual source of X-rays in an image taken by Chandra in 2009. They then followed its evolution with ESA’s XMM-Newton space observatory.
“X-ray sources with such extreme luminosity are rare outside galaxy nuclei and can serve as a key probe for identifying elusive IMBHs. They represent a crucial missing link in black hole evolution between stellar mass and supermassive black holes,” said lead author Yi-Chi Chang of the National Tsing Hua University, Hsinchu, Taiwan.
X-ray emission coming from NGC 6099 HLX-1 has a temperature of 3 million degrees, consistent with a tidal disruption event. Hubble found evidence for a small cluster of stars around the black hole. This cluster would give the black hole a lot to feast on, because the stars are so closely crammed together that they are just a few light-months apart (about 500 billion miles).
The suspected IMBH reached maximum brightness in 2012 and then continued declining to 2023. The optical and X-ray observations over the period do not overlap, so this complicates the interpretation. The black hole may have ripped apart a captured star, creating a plasma disk that displays variability, or it may have formed a disk that flickers as gas plummets toward the black hole.
“If the IMBH is eating a star, how long does it take to swallow the star’s gas? In 2009, HLX-1 was fairly bright. Then in 2012, it was about 100 times brighter. And then it went down again,” said study co-author Roberto Soria of the Italian National Institute for Astrophysics (INAF). “So now we need to wait and see if it’s flaring multiple times, or there was a beginning, there was peak, and now it’s just going to go down all the way until it disappears.”
The IMBH is on the outskirts of the host galaxy, NGC 6099, about 40,000 light-years from the galaxy’s center. There is presumably a supermassive black hole at the galaxy’s core, which is currently quiescent and not devouring a star.
Black Hole Building BlocksThe team emphasizes that doing a survey of IMBHs can reveal how the larger supermassive black holes form in the first place. There are two alternative theories. One is that IMBHs are the seeds for building up even larger black holes by coalescing together, since big galaxies grow by taking in smaller galaxies. The black hole in the middle of a galaxy grows as well during these mergers. Hubble observations uncovered a proportional relationship: the more massive the galaxy, the bigger the black hole. The emerging picture with this new discovery is that galaxies could have “satellite IMBHs” that orbit in a galaxy’s halo but don’t always fall to the center.
Another theory is that the gas clouds in the middle of dark-matter halos in the early universe don’t make stars first, but just collapse directly into a supermassive black hole. NASA’s James Webb Space Telescope’s discovery of very distant black holes being disproportionately more massive relative to their host galaxy tends to support this idea.
However, there could be an observational bias toward the detection of extremely massive black holes in the distant universe, because those of smaller size are too faint to be seen. In reality, there could be more variety out there in how our dynamic universe constructs black holes. Supermassive black holes collapsing inside dark-matter halos might simply grow in a different way from those living in dwarf galaxies where black-hole accretion might be the favored growth mechanism.
“So if we are lucky, we’re going to find more free-floating black holes suddenly becoming X-ray bright because of a tidal disruption event. If we can do a statistical study, this will tell us how many of these IMBHs there are, how often they disrupt a star, how bigger galaxies have grown by assembling smaller galaxies.” said Soria.
The challenge is that Chandra and XMM-Newton only look at a small fraction of the sky, so they don’t often find new tidal disruption events, in which black holes are consuming stars. The Vera C. Rubin Observatory in Chile, an all-sky survey telescope from the U.S. National Science Foundation and the Department of Energy, could detect these events in optical light as far as hundreds of millions of light-years away. Follow-up observations with Hubble and Webb can reveal the star cluster around the black hole.
The Hubble Space Telescope has been operating for more than three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Related Images & Videos NGC 6099 (Hubble + Chandra)A Hubble Space Telescope image of a pair of galaxies: NGC 6099 (lower left) and NGC 6098 (upper right). The purple blob depicts X-ray emission from a compact star cluster. The X-rays are produced by an intermediate-mass black hole tearing apart a star.
NGC 6099 (Hubble)
A Hubble Space Telescope image of a pair of galaxies: NGC 6099 (lower left) and NGC 6098 (upper right). The white dot labeled HLX-1 is the visible-light component of the location of a compact star cluster where an intermediate-mass black hole is tearing apart a star.
NGC 6099 Compass Image
This compass image shows two elliptical galaxies, NGC 6098 at upper right and NGC 6099 at lower left. The fuzzy purple blob at bottom center shows X-ray emission produced by an intermediate-mass black hole tearing apart a star.
HLX-1 Illustration
This sequence of artistic illustrations, from upper left to bottom right, shows how a black hole in the core of a star cluster captures a bypassing star and gravitationally shreds it until there is an explosion, seen in the outskirts of the host galaxy.
HLX-1 Animation
This video is an illustration of an intermediate-mass black hole capturing and gravitationally shredding a star. It begins by zooming into a pair of galaxies. The galaxy at lower left, NGC 6099, contain a dense star cluster at center. The video then zooms into the heart of the cl…
Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
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Space Telescope Science Institute
Baltimore, Maryland
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NASA, JAXA XRISM Satellite X-rays Milky Way’s Sulfur
4 min read
NASA, JAXA XRISM Satellite X-rays Milky Way’s SulfurAn international team of scientists have provided an unprecedented tally of elemental sulfur spread between the stars using data from the Japan-led XRISM (X-ray Imaging and Spectroscopy Mission) spacecraft.
Astronomers used X-rays from two binary star systems to detect sulfur in the interstellar medium, the gas and dust found in the space between stars. It’s the first direct measurement of both sulfur’s gas and solid phases, a unique capability of X-ray spectroscopy, XRISM’s (pronounced “crism”) primary method of studying the cosmos.
“Sulfur is important for how cells function in our bodies here on Earth, but we still have a lot of questions about where it’s found out in the universe,” said Lía Corrales, an assistant professor of astronomy at the University of Michigan in Ann Arbor. “Sulfur can easily change from a gas to a solid and back again. The XRISM spacecraft provides the resolution and sensitivity we need to find it in both forms and learn more about where it might be hiding.”
A paper about these results, led by Corrales, published June 27 in the Publications of the Astronomical Society of Japan.
Watch to learn how the XRISM (X-ray Imaging and Spectroscopy Mission) satellite took an unprecedented look at our galaxy’s sulfur. XRISM is led by JAXA (Japan Aerospace Exploration Agency) in collaboration with NASA, along with contributions from ESA (European Space Agency).NASA’s Goddard Space Flight Center
Using ultraviolet light, researchers have found gaseous sulfur in the space between stars. In denser parts of the interstellar medium, such as the molecular clouds where stars and planets are born, this form of sulfur quickly disappears.
Scientists assume the sulfur condenses into a solid, either by combining with ice or mixing with other elements.
When a doctor performs an X-ray here on Earth, they place the patient between an X-ray source and a detector. Bone and tissue absorb different amounts of the light as it travels through the patient’s body, creating contrast in the detector.
To study sulfur, Corrales and her team did something similar.
They picked a portion of the interstellar medium with the right density — not so thin that all the X-rays would pass through unchanged, but also not so dense that they would all be absorbed.
Then the team selected a bright X-ray source behind that section of the medium, a binary star system called GX 340+0 located over 35,000 light-years away in the southern constellation Scorpius.
This composite shows a section of the interstellar medium scientists X-rayed for sulfur using the Japan-led XRISM (X-ray Imaging and Spectroscopy Mission). X-ray binary GX 340+0 is the blue dot in the center. The composite contains a blend of imagery in X-rays (represented in deep blue), infrared, and optical light.DSS/DECaPS/eRosita/NASA’s Goddard Space Flight Center This composite shows a section of the interstellar medium scientists X-rayed for sulfur using the Japan-led XRISM (X-ray Imaging and Spectroscopy Mission). The X-ray binary 4U 1630–472 is highlighted at the center. The composite contains a blend of imagery in X-rays (represented in deep blue), infrared, and optical light.DSS/DECaPS/eRosita/NASA’s Goddard Space Flight CenterUsing the Resolve instrument on XRISM, the scientists were able to measure the energy of GX 340+0’s X-rays and determined that sulfur was present not only as a gas, but also as a solid, possibly mixed with iron.
“Chemistry in environments like the interstellar medium is very different from anything we can do on Earth, but we modeled sulfur combined with iron, and it seems to match what we’re seeing with XRISM,” said co-author Elisa Costantini, a senior astronomer at the Space Research Organization Netherlands and the University of Amsterdam. “Our lab has created models for different elements to compare with astronomical data for years. The campaign is ongoing, and soon we’ll have new sulfur measurements to compare with the XRISM data to learn even more.”
Iron-sulfur compounds are often found in meteorites, so scientists have long thought they might be one way sulfur solidifies out of molecular clouds to travel through the universe.
In their paper, Corrales and her team propose a few compounds that would match XRISM’s observations — pyrrhotite, troilite, and pyrite, which is sometimes called fool’s gold.
The researchers were also able to use measurements from a second X-ray binary called 4U 1630-472 that helped confirm their findings.
“NASA’s Chandra X-ray Observatory has previously studied sulfur, but XRISM’s measurements are the most detailed yet,” said Brian Williams, the XRISM project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Since GX 340+0 is on the other side of the galaxy from us, XRISM’s X-ray observations are a unique probe of sulfur in a large section of the Milky Way. There’s still so much to learn about the galaxy we call home.”
XRISM is led by JAXA (Japan Aerospace Exploration Agency) in collaboration with NASA, along with contributions from ESA (European Space Agency). NASA and JAXA developed Resolve, the mission’s microcalorimeter spectrometer.
Download images and videos through NASA’s Scientific Visualization Studio.By Jeanette Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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NASA Scientist Finds Predicted Companion Star to Betelgeuse
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) An image of Betelgeuse, the yellow-red star, and the signature of its close companion, the faint blue object.Data: NASA/JPL/NOIRlab. Visualization: NOIRLAB.
A century-old hypothesis that Betelgeuse, the 10th brightest star in our night sky, is orbited by a very close companion star was proved true by a team of astrophysicists led by a scientist at NASA’s Ames Research Center in California’s Silicon Valley.
The research published in The Astrophysical Journal Letters in the paper “Probable Direct Imaging Discovery of the Stellar Companion to Betelgeuse.”
Fluctuations in the brightness and measured velocity of Betelgeuse, the closest red supergiant star to Earth, had long presented clues that it may have a partner, but the bigger star’s intense glow made direct observations of any fainter neighbors nearly impossible.
Two recent studies by other teams of astronomers reignited the companion star hypothesis by using more than 100 years of Betelgeuse observations to provide predictions of the companion’s location and brightness.
If the smaller star did exist, the location predictions suggested that scientists had a window of just a few months to observe the companion star at its widest separation from Betelgeuse, as it orbited near the visible edge of the supergiant. After that, they would have to wait another three years for it to orbit to the other side and again leave the overpowering glow of its larger companion.
Searches for the companion were initially made using space-based telescopes, because observing through Earth’s atmosphere can blur images of astronomical objects. But these efforts did not detect the companion.
Steve Howell, a senior research scientist at Ames, recognized the ground-based Gemini North telescope in Hawai’i, one of the largest in the world, paired with a special, high-resolution camera built by NASA, had the potential to directly observe the close companion to Betelgeuse, despite the atmospheric blurring.
Officially called the ‘Alopeke speckle instrument, the advanced imaging camera let them obtain many thousands of short exposures to measure the atmospheric interference in their data and remove it with detailed image processing, providing an image of Betelgeuse and its companion.
Howell’s team detected the very faint companion star right where it was predicted to be, orbiting very close to the outer edge of Betelgeuse.
“I hope our discovery excites other astrophysicists about the robust power of ground-based telescopes and speckle imagers – a key to opening new observational windows,” said Howell. “This can help unlock the great mysteries in our universe.”
To start, this discovery of a close companion to Betelgeuse may explain why other similar red supergiant stars undergo periodic changes in their brightness on the scale of many years.
Howell plans to continue observations of Betelgeuse’s stellar companion to better understand its nature. The companion star will again return to its greatest separation from Betelgeuse in November 2027, a time when it will be easiest to detect.
Having found the long-anticipated companion star, Howell turned to giving it a name. The traditional star name “Betelgeuse” derives from Arabic, meaning “the hand of al-Jawza’,” a female figure in old Arabian legend. Fittingly, Howell’s team named the orbiting companion “Siwarha,” meaning “her bracelet.”
Photo of the constellation Orion, showing the location of Betelgeuse – and its newfound companion star.NOIRLab/Eckhard Slawik
The NASA–National Science Foundation Exoplanet Observational Research Program (NN-EXPLORE) is a joint initiative to advance U.S. exoplanet science by providing the community with access to cutting-edge, ground-based observational facilities. Managed by NASA’s Exoplanet Exploration Program, NN-EXPLORE supports and enhances the scientific return of space missions such as Kepler, TESS (Transiting Exoplanet Survey Satellite), Hubble Space Telescope, and James Webb Space Telescope by enabling essential follow-up observations from the ground—creating strong synergies between space-based discoveries and ground-based characterization. NASA’s Exoplanet Exploration Program is located at the agency’s Jet Propulsion Laboratory.
To learn more about NN-EXPLORE, visit:
https://exoplanets.nasa.gov/exep/NNExplore/overview
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