Astronomers find a virgo galaxy spinning out of sync

A strange virgo Galaxy spinning in a way which defies expectations

A new Hubble Space Telescope image reveals the unusual structure and mysterious rotation of the spiral galaxy NGC 4698. Image revealed that the spiral galaxy NGC 4698 hides a strange internal arrangement, with its central region rotating in a different direction from the rest of the galaxy. The discovery, presented by ESA, offers astronomers a closer look at how galaxies can be shaped by interactions and events which happened billions of years ago. Though the spiral galaxy in the new image by the NASA/ESA Hubble Space Telescope seems serene, it hides a chaotic secret. This galaxy is NGC 4698, and it lies about 55 million light-years away in the constellation Virgo. It’s one of over one thousand galaxies in the Virgo Cluster, the nearest large cluster of galaxies bound together by gravity. As a spiral galaxy similar to our own Milky Way galaxy, NGC 4698 has spiral arms which curl around within a thin disc of stars, gas and dust. Its centre is dominated by a galactic bulge.

The spiral galaxy NGC 4698 is spinning out of sync because the stars and gas near its center rotate perpendicular (at a right angle) to the rest of its stellar disc. It belongs to the massive Virgo Cluster, which contains over a thousand galaxies. It features a central stellar bulge which extends outward from the main disc at an unusual right angle. Astronomers believe the strange rotation comes from external sources.  The galaxy may have pulled in gas from an outside location, forming a new inner disc tilted against the original rotation. Evidence like a faint tail of hydrogen gas near the galaxy suggests it went through a minor collision or merger with a smaller galaxy in its past. The diffuse off-white glow of the galaxy’s bulge comes from stars smaller, older, and cooler than the massive blue stars which dot the galaxy’s outer disc. These tightly packed stars orbit a supermassive black hole containing millions of times the Sun’s mass. Scientists have found signs that this black hole is actively growing, drawing gas inward with its gravitational pull.

NGC 4698 appears at first glance to be a typical spiral galaxy with elegant arms surrounding a bright center. Yet beneath this calm appearance lies a complex structure that separates it from most known spiral galaxies. Its central bulge extends at an unusual angle compared with the galaxy’s main disk, creating a rare example of a galaxy whose components are not aligned. The ESA release explains that NGC 4698 is a spiral galaxy which looks familiar from a distance but contains a hidden complexity. Its unusual rotation pattern and tilted central bulge provide clues about interactions that may have occurred in the distant past. With a flat, starry disc and diffusely glowing centre, NGC 4698 looks a lot like a typical spiral galaxy, but this galaxy is far from normal. NGC 4698 is one of only a few known spiral galaxies with a bulge that extends out from the disc at a right angle. The elongation is faintly visible in the Hubble image, which shows the ghostly glow of the starry bulge peeking above and below the dusty disc. Astronomers believe that material from outside the galaxy may have played a role in creating this unusual arrangement. If NGC 4698 captured gas from another source, that material could have formed a new disk of gas and stars around the center at a different angle from the original galactic disk. The galaxy also shows possible signs of a previous minor merger. Observations have detected a short stream of hydrogen extending from one side of the galaxy, which could be evidence that another galaxy interaction influenced its current shape.

Astronomers have found that the culprit likely lies outside the galaxy. If NGC 4698 funneled in gas from an outside source, the newly collected gas could have formed a disc of gas and stars in the galaxy’s centre. Some observations suggest that this galaxy once experienced a minor galactic merger, as evidenced by a short ‘tail’ of hydrogen streaming from one side of the galaxy. The data used to create this image come from an observing programme (#18103; PI: Thilker) focusing on galaxies in the Virgo Cluster. The spiral galaxy NGC 4698 have a massive collection of more than one thousand galaxies held together by gravity. Like the Milky Way, it contains a thin disk made of stars, ga, and dust, along with a dense central bulge filled with older stars. The outer disk contains areas where younger, hotter stars shine with blue tones, while the central bulge produces a softer off-white glow created by older and cooler stars. This contrast reveals the different populations of stars that exist within the galaxy. What makes NGC 4698 unusual is the position of its bulge. Instead of extending along the same plane as the disk, the central structure appears tilted at nearly a right angle. Astronomers have identified only a small number of spiral galaxies with this type of configuration.

The inner stars and gas near the galaxy’s center also rotate differently from the material farther out. This mismatch indicates that the galaxy’s history involved processes capable of disturbing its original structure while allowing it to maintain its spiral appearance. Prominent red-brown dust lanes weave through the arms, which are also dotted with bright blue and reddish regions of star formation. The galaxy is set against a dark background scattered with stars and faint distant galaxies. At the center of NGC 4698 lies a supermassive black hole containing millions of times the mass of the Sun. The dense population of older stars in the bulge surrounds this powerful object, creating the bright central region visible in the Hubble image. Researchers have found indications that this black hole is actively growing by pulling gas inward through its intense gravitational field. The movement of material around the center provides scientists with information about both the black hole and the galaxy hosting it. The relationship between a galaxy and its central black hole remains one of the major areas of study in modern astronomy. Many galaxies appear to have developed alongside their central black holes, with each influencing the evolution of the other over cosmic timescales. In NGC 4698, the unusual orientation of the central region creates an opportunity to examine how black holes, gas flows, and galaxy interactions can combine to shape a galaxy’s future. 

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Major ice losses for Greenland and Antarctica observed thru Satellite

 Satellites data shows loss of more than 12 trillion tons of ice from Greenland and Antarctica

The Jakobshavn glacier in Greenland is now retreating up to 50 meters a day. Greenland and Antarctica lost 11.3 trillion tons of ice. Findings based on satellite data spanning 1979 to 2023. This added 1.24 inches (3.14 cm) to global sea levels. About 12.5 trillion tons of ice from glaciers in Greenland and Antarctica have melted since 1979, which is enough frozen water to stack ice five feet deep across the continental US, according to a major scientific report. New research based on satellite data going ​back to the 1970s has documented major polar ice losses in Greenland and Antarctica, home to Earth's two ‌great ice sheets, which have contributed to rising global sea levels. Between 1979 and 2023, according to data from 27 satellite missions, Greenland and Antarctica lost a combined 11.3 trillion tons of ice.

The study, employing the longest satellite data record of changes ​in ice sheets ever gathered to give the most complete account to date of ice loss in Greenland and ​Antarctica, was conducted by the Ice Sheet Mass Balance Inter-comparison Exercise team, an international group of polar ⁠scientists. The findings, they said, offer fresh evidence of the effects of human-caused global climate change. A warming Earth is accelerating the melting of the planet’s two major ice sheets, with five-sixths of the melt not coming from hotter air, but from warmer waters eating away at the ice sheets from below and the sides, with glaciers flowing into the oceans, according to a study. That’s bad news for future sea level rise, the study’s authors said. “The ice sheets are melting away fast,” said study co-author Eric Rignot, an ice scientist at University of California, Irvine. “We are melting the polar regions, sea level is rising worldwide and will exacerbate the vulnerability of coastal regions.” The numbers behind the melting ice are both mind-bogglingly huge and deceptively small. All that melted ice turned into nearly 3 quadrillion gallons of water, which pushed global sea levels up about an inch since 1979, on top of other climate factors raising ocean heights, the report said. An inch may not sound like much, but for every third of an inch of sea level rise, another 2 million to 3 million people get flooded at least once a year, said lead study author Ines Otosaka, an ice scientist at Northumbria University in England. The Jakobshavn glacier in Greenland is now retreating up to 164 feet a day, Otosaka said. "To put this very large number into ​context, 11.3 trillion tons of ice is enough ice to fill in a cube that would be 23 km's (14.3 miles) in height," ​said Otosaka. Of the ice loss documented in the study, about 60% came from Greenland and 40% from Antarctica, even though Greenland is about one-eighth the size of Antarctica.

The international collaboration of polar scientists, headed by the European Space Agency, had in the past only looked at ice sheet melt since the 1990s based on European satellite data. But by incorporating NASA satellites, the scientists were able to chart ice sheet volumes in Antarctica back to 1979 and in Greenland back to 1972. "When ice ​sheets melt, they contribute to rising global sea levels. The ice sheets are now a major driver of sea-level rise, accounting for about 25% ‌of ⁠all sea-level rise," Otosaka said. "We have extended our satellite data record backwards in time to the 1970s, and this confirms that ice losses started in the 1990s and have increased since then. Our assessment shows that the pace of ice loss increased by a factor of four between the 1980s and 2010s," Otosaka said. “There is a clear trend that the ice sheets are losing more mass and it has been increasing from decade to decade, especially if you look at the ice being discharged to the ocean. And that’s quite clear that there’s a link to climate change.” It showed that in the 1970s, 1980s and into the 1990s, the ice sheets were relatively stable, but then melt started happening, and it really kicked in during the 2010s, Otosaka said.

The study documented a slowdown in ice loss between 2020 and 2023, though ​the researchers said this appears to ​represent a short-term variation ⁠and not a reversal of the long-term trend. Unusually high snowfall across East Antarctica provided enough ice to offset some of the losses from glaciers elsewhere on Antarctica, while relatively mild summers in ​Greenland substantially lowered surface melting, they said. Some 84% of the ice lost came from glaciers ​flowing more quickly into ⁠the ocean rather than from ice melting at the surface, showing that the long-term trend is being driven by the response of the ice sheets to a warming ocean, Otosaka said. The researchers said the total sea-level rise attributed to the ice losses at Greenland and ⁠Antarctica may ​not sound like a huge number, but it puts another 6 to 9 ​million people at risk of coastal flooding and erosion globally. “That’s something to be concerned about as it shows that the changes are tracking decades behind global warming, which means we can expect them to continue for decades more, even if we are able to stop heating the planet,” said study co-author Andrew Shepherd, also of Northumbria.

The study’s authors said that it more reflected short-term weather variations, not long-term trends. Otosaka said the study stopped with 2023 data, but she’s looked at measurements since and found the accelerating trend has picked back up. A lot of the stability in Antarctica was because East Antarctica had record snowfall, which compensated for the rapid melting in the less stable West Antarctic Ice Sheet. The three-year hiatus was “just a bump in the record,” Rignot said. “The long rise is climate, and the threat is crystal clear.” The biggest changes scientists saw are in what they call dynamic processes, which are more abrupt and active than the slow, steady melting from the air, and that’s something prone to trigger runaway “tipping points,” Otosaka said. New York University ice scientist David Holland said that’s what concerns him “because most of the ice loss is dynamical and that is exactly what you would expect in an ice sheet instability collapse scenario.” The international team used 45 independent surveys and 27 different satellites. “The use of relatively independent methods gives me greater confidence in the result,” said Holland, who wasn’t part of the study. “The upward trend is real.” 

“The ‘wild cards’ of Antarctic mass loss continue to pose a challenge for human management of the planet, a clear and present danger, but many decades in the future,” said University of Colorado ice scientist Ted Scambos, who wasn’t part of the study. “We are now as a society smart enough to know the future, but not prudent enough to act upon the knowledge.” These findings have implications for coastal planning, showing that we urgently need to develop plans for protecting coastal ​communities around the world from the impact of ice sheet melting," Otosaka said as conclusion.

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