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Indian scientists plan to seed clouds for the first time to trigger heavy rain in some areas of New Delhi, hoping this will be enough to tackle the smog gripping the world’s most polluted capital for a week, the project’s head said on Thursday.

Air quality dips in Delhi ahead of winter every year, when cold air traps pollutants from a variety of sources including vehicles, industries, construction dust, and agricultural waste burning. 

Scientists expect some cloud cover over the city around November 20 and are hoping this will be large enough — and with high enough moisture content — to trigger heavy rain via seeding with salts, said Manindra Agrawal, a scientist at the Indian Institute of Technology at Kanpur, who is leading the trial.

The project, estimated to cost Rs. 1 crore for 100 square kilometres, would involve spraying into clouds a mix of salts that include silver iodine, Agrawal said.

“We don’t expect that big a cloud that will cover entire Delhi, but a few hundred kilometres would be good,” he told Reuters. 

The local government of the city of 20 million people, spread over roughly 1,500 square kilometres, has already shut all schools, stopped construction activities, and said it will impose restrictions on vehicle use to control pollution.

The air quality index in the city was 506 early on Thursday, which is categorised as “hazardous” by Swiss group IQAir.

Delhi needs heavy and widespread rain to wash away the pollutants, and light rain could worsen the situation, said Gufran Beig, the founder director of the federal government’s air-quality monitoring agency SAFAR.

Beig added that current airflow is carrying smoke from crop residue burning in the states of Punjab and Haryana to Delhi, which also has its own pollution sources and where there is currently almost no wind. 

“So unless a huge pressure is established by intense rain, this chain of transport from Punjab to Delhi will not be broken, and once it is broken it is difficult for the chain to form again for some time,” he told Reuters. 

About 38 percent of the pollution in the capital has been caused by stubble burning in Punjab and Haryana, where over 22,000 stubble burning events were recorded between September 15 and November 7, according to a government statement.

Stubble burning is a practice followed by farmers wherein crop stubble left behind after rice is harvested is burnt to quickly clear fields before planting wheat crops. 

The federal government has directed authorities in both states to “take effective actions” to check further stubble burning, the statement added. 

The Delhi government is seeking to get approval for the project from the Supreme Court, which is hearing petitions related to pollution.

Several countries have used cloud seeding to produce rain, improve air quality and water crops in time of drought, including Mexico, the United States, China, Indonesia and Malaysia. 

However, in 2021, a plan to seed clouds over the mountains of New Mexico to increase snowfall was pulled after allegations it could poison people and the environment.

© Thomson Reuters 2023

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Hubble finds missing globular cluster in Milky Way’s crowded stellar halo

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July 5, 2025

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Hubble finds missing globular cluster in Milky Way’s crowded stellar halo

A striking new image captured by NASA’s Hubble Space Telescope has shed light on an underexplored gatekeeper of our galactic neighbours’ achievements and tragedies. Adorned with multi-hued stars, the spherical cluster glitters amid the expanse of stars in our Milky Way galaxy. This type of globular cluster is a very dense grouping of stars — about the same mass as 100,000 suns — that orbit all around the centre of their galaxy. Stars in a cluster are typically roughly the same age, as they formed from the same collapsing gas cloud. In this new view, stars show up in temperatures indicated in red and blue colours: red for colder and blue for hotter stars.

Hubble Maps Forgotten Star Cluster ESO 591-12 to Uncover Milky Way’s Ancient Stellar Secrets

As per a report from NASA’s Hubble team, ESO 591-12 was imaged during the Hubble Missing Globular Clusters Survey—an initiative targeting 34 Milky Way globular clusters that had never been observed by the space telescope. The aim is to construct a comprehensive database of the ages, distances, and stellar populations of all the galaxy’s known globular clusters and star formations. However, it has always been tough for telescopes on Earth to pick out individual stars in these densely populated regions, so Hubble’s high resolution has done much to finally be able to track the movements of stars to unlock their histories and formation.

The ESO 591-12 data are part of an ongoing study to improve knowledge of the formation and evolution of globular clusters in the galaxy’s bulge and halo. These star clusters are cosmic fossils that have preserved cosmic conditions from the primordial universe. Their work helps build a fuller narrative of the evolution of the Milky Way and how it has changed over billions of years.

This new image is a further example of how advanced space-based observing facilities are helping astronomers to excavate the contents of the dark and dusty skeleton cloaking the Milky Way and sculpt a better understanding of not only the universe’s evolution but also that of our cosmic home.
Each one tells part of the astronomical story, and Hubble is digging out new chapters to enrich the tale, such as probing data for clusters as much as ESO 591-12, which have been mostly neglected until now. This finding adds to our knowledge of the early universe by shining a spotlight on something that was in plain sight.

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Very Massive Stars Blow Away Outer Layers in Powerful Winds Before Black Hole Collapse

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Massive stars shed extreme mass before collapsing into black holes

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July 5, 2025

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Massive stars shed extreme mass before collapsing into black holes

New research indicates that the most monstrously huge stars — those more than 100 times as massive as the sun — shed at least 20 times more matter before they collapse than previously thought to do so as they cool off to become black holes. These stars blow off a significant portion of their outer layers in quite powerful stellar winds over the brief but intense course of their lives, leaving behind low masses at the end. One benefit of this extreme mass loss is that it can account for observed strangeness in stars such as those in the Tarantula Nebula, providing new information on stellar evolution, black hole formation, and sources of gravitational waves.

Hurricane-like Stellar Winds Explain Extreme Mass Loss in Universe’s Most Massive Stars

As per a report from Space.com, researchers used sophisticated models and observations to learn that very massive stars give off winds so powerful they act more like hurricanes than gentle solar breezes. Their results agree very well with observations of WNh-type Wolf-Rayet stars in the Tarantula Nebula, which are hotter and more compact than would be expected by standard models. The improved models explain the very high temperatures at the surface and the stability of hydrogen, which address previous challenges.

One key subject in this study is R136a1 — the most massive known star — with a mass up to 230 times that of the sun. The researchers suggested that it either formed as a single star of around 200 solar masses or as a binary star system where the two stars had a combined mass of about 200 solar masses. In both such cases, the star must have lost a huge amount of mass early in its life, so the findings would call into question how it is that massive stars can live long enough to leave such a wreckage in the Large Magellanic Cloud.

The implications extend to black hole formation as well. More massive stellar winds erode more mass, resulting in the production of smaller black holes and decreasing the chances of creating elusive intermediate-mass black holes. This revision also enhances the matches of the model with the observed gravitational wave signal of a coalescing black hole binary.

Although the models are restricted to stars in the Tarantula Nebula, the researchers stress that in order for their findings to be considered universal, it is important to understand stars in different chemical environments as well. The results not only reshape predictions of black hole populations but may also adjust our understanding of how the most massive stars in the universe live — and die.

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New Interstellar Comet 3I/ATLAS Speeds Through Solar System

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Astronomers Capture First-Ever Image of a Dead Star That Exploded Twice in Rare Supernova Event

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July 5, 2025

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Astronomers Capture First-Ever Image of a Dead Star That Exploded Twice in Rare Supernova Event

For the first time, a team of astronomers has captured a clear image of a white dwarf star that exploded not just once, but twice, as a Type Ia supernova — a “double-detonation” that scientists hadn’t thought possible until now. The extraordinary observation could revise our long-held notions of how stars die, suggesting that some stars can explode as supernovas without ever crossing the Chandrasekhar limit, the minimum mass normally thought necessary for such an explosion. The astronomers employed the Very Large Telescope’s MUSE instrument to zoom in on the four-century-old supernova remnant SNR 0509-67.5, which sits 60,000 light-years away in the constellation Dorado, revealing evidence of two separate blasting catastrophes in its construction.

First Visual Proof Shows White Dwarfs Can Explode Twice Without Reaching Chandrasekhar Limit

As the researchers report on July 2 in Nature Astronomy, the team found a distinctive “fingerprint” in the debris of SNR 0509-67.5 in the Large Magellanic Cloud that the models predicted. White dwarfs—which are the dead stage of sun-like stars—usually blow up into Type Ia supernovas after they hit the Chandrasekhar limit by stealing matter from a neighbouring star.

However, this finding shows that the detonation can be launched at an earlier time. The explosion is likely to have a two-step origin, the team argues, with the initial blast being generated when an unstable layer of helium that the star had acquired exploded on its surface; the resulting shock wave then drove a second and main detonation.

“This physical proof of a double-detonation not only helps solve a long-standing mystery of what causes these explosions, but it represents the most visually compelling evidence for this origin.” Priyam Das, University of New South Wales, team leader and author.

Something is happening to Type Ia supernovas, the “standard candles” used to measure cosmic distances, because their brightness doesn’t fluctuate. But they have long mystified scientists with how they explode. Until this discovery, an explosion white dwarf that didn’t surpass the Chandrasekhar limit was only considered in theory.

This fresh visual evidence for the double detonation model further informs our knowledge of stellar evolution and also informs how we should interpret light from distant supernovas. More than its scientific implications, its discovery adds a colourful new page to the story of dying stars — stars that, as it now appears, will not go gently into that night but will light up the sky twice over in fantastic fireworks before vanishing from the cosmos.

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