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We first saw a star devouring a planet



An artist’s impression of a planet about to be swallowed up by a star

K. Miller and R. Hurt/Caltech/IPAC

For the first time, astronomers have caught a star devouring one of its planets. Someday our own sun will expand like this star, engulfing the other inner planets, so this system is a kind of preview of the fate of the Earth.

Kishalay De at MIT and colleagues used the Zwicky Transient Facility in California to detect a strange burst of light, designated ZTF SLRN-2020, from a star about 13,000 light-years away. Within about 10 days, it became brighter by about 100 times.

The outburst was similar to a phenomenon called a red nova, caused by the merger of two stars, but it was not as bright and did not release as much energy. By collecting more observations with other telescopes, the researchers found that the data is consistent with the fact that the star is not swallowing another star, but a gas giant planet at least 30 times the mass of the Earth.

We knew that stars ate planets because we saw the consequences of polluting stars with chemicals from the worlds they devoured. “In the past, all the evidence we have that stars eat planets came from observations of stars that did so hundreds of thousands of years ago,” says De. “But we’ve never caught a star red-handed eating a planet.”

This is expected to happen when the sun-like star uses up its hydrogen fuel and switches to helium fusion. In the process, the star becomes a red giant, and its atmosphere expands outward, engulfing any planets that unfortunately orbit too closely. In the case of ZTF SLRN-2020, it took the planet less than one Earth day to orbit its star.

The sun should begin its expansion in about 5 billion years. “In fact, we see how the fate of our own planet in real time happens to another unfortunate planet,” says De. “If you were to observe our solar system from 10,000 light-years away, you would see the Sun also getting brighter in the same way, but the effect would be nowhere near as dramatic because the Earth is much smaller than the Earth. [the planet] is.”

De said that now that we know what planetary absorption looks like, it will be much easier to search for them and study them in more detail. The researchers calculated that this should happen about once a year in our galaxy, so we should be able to find more planets being devoured by their stars, as well as keep watching this one and figuring out the details of the process – and Earth’s future doom.



NASA welcomes the Czech Foreign Minister on the signing of the Artemis Accords



During a ceremony at NASA headquarters in Washington on Wednesday, the Czech Republic became the 24th signatory to the Artemis Accord. NASA Administrator Bill Nelson attended the signing ceremony for the agency, and Foreign Minister Jan Lipavsky signed the Artemis Accords on behalf of the Czech Republic.

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The oceans lack their rivers




GFrom the eighth floor of a hotel in Georgetown, Guyana, the wide expanse of the Atlantic Ocean looked dirty brown. Only a thin blue border on the horizon showed the true color of the ocean; the rest were swirled by sediments coming out of the mouth of the Essequibo River.

In a rhythm that pulsates through the ages, the river plume carries sediment and nutrients from the interior of the continent to the ocean, the main exchange of resources from land to sea. More than 6,000 rivers around the world carry fresh water to the oceans, delivering nutrients, including nitrogen and phosphorus, that feed phytoplankton, giving rise to the flourishing of life, which in turn feeds ever larger creatures. They may even influence ocean currents in ways that researchers are only just beginning to understand. But today, in rivers around the world, people are aging from this critical phenomenon.

In many places, the main culprit is the dam: a wall of concrete and stone that bisects a river and diverts its energy and water to human needs. There is 58,000 “big ladies”– 50 feet tall or taller – worldwide, 3,700 more planned, mostly in low-income countries in Asia and South America.

Sea level rise deserves headlines, but sunken land is no less a problem.

Many of the harms caused by dams are well documented. They block the passage of fish and starve the fishermen who fish; radically change the natural regimes of rivers and the life cycles of aquatic creatures; and flooded forests, wetlands, villages and historic sites. (so they less climate friendly1 another reliable2 than is widely believed.) Scientists now describe another impact that has received relatively little attention, but which also appears to be serious: dams block sediment-carrying river surges into the ocean.

The researchers used satellite data to evaluate sediment changes over the past 40 years in 414 rivers around the world and found that dams in the global north—North America, Europe and Asia—blocked 49 percent of sediment delivery to coasts.3 This conclusion, which was published last year in the journal The science, is even more startling when you consider the frenzy of dam building that took place in the 1970s. The baseline survey of the early 1980s probably already showed a significant deviation from the natural state of the rivers.

“People have built structures that have vastly outperformed the effects of climate change in many ways,” says Evan Dethier, an oceanographer at Bowdoin College and lead author of the study.

Sediments play a vital role in river and coastal systems. As rivers reach their floodplains, the water slows down, shedding the silt that shapes its course and nourishes the vegetation that grows among the canals. The sediments also bring nutrients to the floodplain, helping to speed up algal blooms, which in turn feed the phytoplankton and juvenile fish. At the edge of the sea, sediments are constantly reclaiming coastal land otherwise eroded by ocean waves. The rising seas deserve the headlines, but the sunken land no less serious problem for people living in river deltas, now devoid of sediment.4

The stories of rivers and the sediment they carry do not end there. The ocean is turbulent, which can cause its currents to meander back and forth like torrents on land. Meanders become unstable, forming whirlpools where strong currents meet weak currents and where fresh water meets denser, often colder, salt water. When rivers empty into the oceans, they form a plume of fresh water that can extend up to 80 miles from the coast; the resulting collision of fresh and salt water, their difference in temperature, and the sediments they carry create chains of whirlpools, similar to the lines of the Congo whirlpools, that affect larger ocean circulation patterns.

In body image
RIVER IN THE SEA: Fresh water from the Mekong River circulates through the South China Sea, pictured here between August and October 2014. Image from Zeng, X., et al. Dynamic impact of the Mekong plume in the South China Sea. JGR Oceans (2022).

Researchers led by Annalize Bracco, an oceanographer at the Georgia Institute of Technology, have studied these dynamics. in the study plume created by the Mekong River, the 12th longest river in the world.5 It flows nearly 3,000 miles from its headwaters in the Tibetan Plateau through China, Myanmar, Thailand, Laos, Cambodia and Vietnam before reaching the South China Sea.

Over 150 dams have been built in the Mekong Basin, including 13 in the main riverbed, and more than 100 additional dams are planned. To understand how they might affect the South China Sea, Bracco’s team created a computer model of how the Mekong plume affects the sea’s circulation today. They then modeled how the plume would behave if more dams were built, drastically reducing the Mekong’s average annual flow and its seasonal cycle.

“You do get different transportation,” says Bracco. Because fresh water is less dense than salt water, plume water tends to stay at the surface, where it can be more easily moved by wind. If the Mekong plume were to decrease, she said, the winds would need more energy to move seawater, slowing down the speed of the currents.

Bracco’s team found that in the South China Sea, summer monsoon winds drive currents northeastward, bringing nutrients, food and warmer temperatures with them. Future dams will cause the eddy current to oscillate, weakening the northward movement of currents and reducing the productivity of the marine ecosystem.

Bracco recalls the time she was on the boat, measuring ecosystem changes along the river’s plume. “You see plankton that emerge and flourish under the influence of river water,” she says. This in turn feeds larger species. “If you drastically change a river so it no longer produces a plume, you prevent the ecosystem from flourishing.”

Dams are less environmentally friendly and reliable than is commonly believed.

Glen Gavarkiewicz, a physical oceanographer at the Woods Hole Oceanographic Institution who studies the Northwest Atlantic, notes that eddy currents carry sediment from river plumes across continental shelves to ocean basins, and fish concentrate on these nutrient fronts. “The decrease in eddies could mean that fewer nutrients are entering ocean basins. And in Southeast Asia, fish is very important for both protein and culture,” says Gavarkevich. Fishing in the South China Sea is already a blast diplomatic disputeshe says, and changes in nutrient circulation could spark new conflicts.

While Bracco’s findings about a likely decline in ocean productivity in the South China Sea are sobering, she cautions that the dynamics she observes are not universal. “Nothing happens the same way everywhere,” she says. For example, the plume of the Mississippi River does not change the direction of currents in the Gulf of Mexico. “The loop current, which is the main ocean current into the Gulf of Mexico, is just so big and so strong.” (Of course, the Mississippi plume has another well-documented impact: nutrient overload from agricultural runoff. creates an extensive dead zone Every year.)

However, it is difficult to accurately estimate the broader impact because today’s climate models – the only tools available to predict the behavior of the Earth system for decades to come – are too low resolution to accurately show the impact of river plumes. The oceanic turbulence tracked by Bracco in the South China Sea, which affects the patterns of eddies and currents, has a scale of one to two kilometers. Most climate models have a resolution of 50 to 100 kilometers. With such a coarse resolution, turbulence from river plumes is not recorded. When existing models try to account for freshwater input from large rivers, they “mix that water in a way that is very different from reality,” says Bracco.

Gavarkevich notes a related issue. In his own research on how fresh water gets into the depths of the ocean, he found that “there are a lot of surprises in it. The dynamics are very complex.” The interaction of wind and water, the mixing of tides, the presence and intensity of sunlight, and eddy movements all affect what happens. But climate models typically use only one variable—the density difference between fresh river plume and salt sea—to represent all of these factors.

Human-induced changes in the quantity, quality and timing of river plumes can have other unpredictable consequences for the ocean. Dam building is not the only way humans are changing river plumes. Instead of holding back sediment, sometimes people release huge amounts of excess sediment.

A study documenting a dramatic reduction in sediment delivery to coasts in the global north found the opposite problem in the global south. Coasts in South America, Africa and Oceania are now receiving 36 percent more sediment than four decades ago, largely due to runoff and erosion caused by clearing forests to make way for palm oil, soybeans, sugar cane and mining.

Over the past decade, the Gulf of Mexico and the Caribbean have experienced a nasty explosion of sargassum seaweed; Bracco believes this will eventually be due to runoff caused by deforestation, which brought excess sediment into the Amazon River plume.

Most ocean impacts caused by anthropogenic changes in river plumes are local rather than global, Bracco said. But with dams already damming two-thirds of the world’s major rivers and thousands more planned, these local impacts could affect ocean life just about anywhere, and we’re only just beginning to reckon with them.

First image: Mekong Delta in Vietnam. Credit: European Space Agency.


1. Fernside, P. M. and Pueyo, S. Greenhouse gas emissions from dams in the tropics. NatureClimate Change 2382-384 (2012).

2. Gies, E. Can wind and solar power secure Africa’s future? Nature 53920-22 (2016).

3. Dethier, E.N., Renshaw, K.E., and Magilligan, F.J. Rapid changes in the global river flow of suspended sediments under human influence. Science 376, 1447-1452 (2022).

4. One Earth Editorial. Keep up with changing deltas. One Earth 6183-184 (2023).

5. Zeng H., Brakko A. and Tagklis F. Dynamic effects of the Mekong plume in the South China Sea. jgr oceans 127e2021JC017572 (2022).

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Scientists Just Watched a Star Eating an Entire Planet



(Cape Canaveral, Florida) – For the first time, scientists have caught a star in the process of swallowing the planet – not just a bite or bite, but one big gulp.

Astronomers on Wednesday reported their observations of what appeared to be a Jupiter-sized or larger gas giant being devoured by its star. The solar star swelled with age for thousands of years and finally became so large that it swallowed up a planet in close orbit.

This is a grim preview of what will happen to Earth when our Sun becomes a red giant and engulfs the four inner planets.

“If it’s any consolation, it will happen in about 5 billion years,” said co-author Morgan Macleod of the Harvard-Smithsonian Center for Astrophysics.

This galactic feast took place between 10,000 and 15,000 years ago near the constellation Aquila, when the star was about 10 billion years old. As the planet descended into the stellar hatch, there was a quick burst of hot light, followed by a continuous stream of dust that shone brightly in cold infrared energy, the researchers said.

read more: James Webb’s latest image reveals new clues about the origin of the universe

While there have previously been signs of other stars gnawing on planets and their digestive effects, this is the first time the swallow itself has been observed, according to a study published in the journal Nature.

MIT researcher Kishalay De spotted the flash of light in 2020 while viewing sky images taken by Caltech’s Palomar Observatory. It took more observations and data processing to unravel the mystery: instead of a star swallowing its companion star, this star swallowed its planet.

Considering a star’s lifespan is billions of years, the ingestion itself was fairly short—essentially in one fell swoop, said Caltech’s Mansi Kasliwal, who participated in the study.

The findings are “very plausible,” said Carol Haswell, an astrophysicist at the British Open University who was not involved in the study. In 2010, Haswell led a team that used the Hubble Space Telescope to identify the star WASP-12 in the process of eating its planet.

“It’s a different kind of food. This star swallowed an entire planet in one gulp,” Haswell wrote in an email. “In contrast, WASP-12 b and other hot Jupiters we’ve previously studied lick and bite delicately.”

Astronomers don’t know if there are more planets orbiting this star at a safer distance. If so, De said, they could have thousands of years before they become second- or third-year stars.

Now that they know what to look for, explorers will look for new space gulps. They suspect that thousands of planets around other stars will suffer the same fate as this one, and ultimately our solar system.

“Everything that we see around us, everything that we have built around ourselves, will disappear in the blink of an eye,” De said.


The Associated Press Department of Health and Science receives support from the Howard Hughes Medical Institute Science and Education Media Group. AP is solely responsible for all content.

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