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Using data from an array of ground based telescopes, astronomers have determined that mysterious cosmic flashes known as luminous fast blue optical transients (LFBOTs) are the result of tidal disruption event by black holes. Here, a black hole containing up to 100 times the mass of the Sun can completely shred a massive stellar companion within days. The clearest evidence yet that these rare cosmic flashes are not merely atypical supernovae is from the LFBOT designated as 2024wpp. The research challenges existing models of black hole physics, and advances the understanding of the life cycles of stars. LFBOTs are among the more puzzling cosmic phenomena discovered over the past few decades. These flashes are bright in blue, ultraviolet light, which fades away rapidly, leaving behind faint X-ray and radio emissions. A little more than a dozen or so of these events have been recorded. Astronomers have long debated if they are caused by unusual supernovae or material falling into a...
Astronomers have used the James Webb Space Telescope to peer into the skies of LP 791-18 c, a sub-Neptune exoplanet orbiting a cool red dwarf star at a distance of 86 lightyears from the Sun. The astronomers expected the world to resemble other temperate sub-Neptunes, straddling the mass gap between Earth and Neptune. Other such worlds have been studied, such as K2-18 b and TOI-270 d that have cloud-free atmospheres rich in methane and carbondioxide. Instead, the astronomers were surprised to discover that LP 791-18 c had a hazy atmosphere rich in methane, with no signs of carbon dioxide. The research indicates that exoplanets that appear similar at first glance may have dramatically different cloudiness, chemistry and evolutionary history. LP 791-18 c is exposed to the same amount of irradiation from the host star as the other comparison targets. The haze on LP 791-18 c is likely to be driven by photochemistry, where the ultraviolet radiation from the red dwarf host star breaks...
New research indicates that scientists are discovering new species faster than ever before, with over 16,000 new species being discovered each year. The discovery of new species is expected to increase in the future, with the research indicating that biodiversity among certain groups, such as plants, fungi, arachnids, fishes and amphibians is far richer than scientists previously thought. Only 15 per cent of the estimated eukaryotic species have been described since the Swedish naturalist Carl Linnaeus set out to identify and name every living organism on Earth 300 years ago. The team examined the taxonomic histories of about two million species spanning all groups of living organisms. Between 2015 and 2020, the researchers documented more than 16,000 new species being described each year, including more than 10,000 animals, dominated by arthropods and insects, 2,500 plants and 2,000 fungi. The rate at which new species are being discovered far outpaces the rate at which species are...
Researchers have investigated how galaxies like our Milky Way form and evolve, with a focus on two distinct groups of stars with different chemical compositions, a feature of the galaxy known as chemical bimodality. The stars close to the Sun can be classified into two types based on their iron and magnesium content. These two groups form separate sequences in a chemical diagram, even though they overlap in metallicity, which is how rich they are in heavy elements such as iron. This differences have long-puzzled astronomers. For the new study, the researchers used sophisticated computer simulations to recreate the formation of galaxies like the Milky Way in a virtual universe. By analysing 30 such simulated galaxies, the researchers explored the formation of the chemical sequences. These simulations help scientists better understand how other large, complex galaxies evolve. Bimodality has not been discovered yet in our sister galaxy, Andromeda. The research also sheds light on the...
Stars form from dense knots in molecular clouds that grow by accreting gas and dust, till the temperatures and pressures rise sufficiently to sustain the fusion of hydrogen and helium. Brown dwarfs are exotic objects that begin to form in the same way as stars, but are unable to sustain hydrogen fusion. They cool off over billions of years, and end up as objects similar to gas giants, but containing many times the mass of Jupiter. Astronomers have discovered atmospheric storms on brown dwarfs, as well as dust clouds. Scientists had assumed that the storms on brown dwarfs were similar to the storms on Jupiter, with clear bands and storms that can remain stable for long durations. The researchers focused on a warm or young brown dwarf, designated as VHS 1256B. Webb had directly detected dust in the clouds of this brown dwarf, that produced a high variation in luminosity over time. These fluctuations indicate dramatic atmospheric features, such as large dust storms. The researchers...
Astronomers have observed wobbles in the inner accretion disk of a black hole for the first time. The process is known as frame-dragging or the Lense-Thirring precession and describes how black holes drag nearby objects such as stars, inducing instabilities in their orbits. The research is based on examination of a tidal disruption event designated as AT2020afhd where a star was torn apart after wandering too close to a black hole. The star was spaghettified, and stretched out into a swirling disk around the black hole. Some of the infalling material was channeled by the tangled magnetic fields produced by the accretion disk itself into relativistic polar jets, with the material from the shredded star moving at nearly the speed of light. By tracking rhythmic changes in both the X-rays and radio signals from the source, the team of astronomers observed that both the disk and the jet were wobbling in unison with a periodicity of 20 days. The observations confirm a prediction of...
New data confirms that collisions between galaxies drive the most powerful active galactic nuclei. Most large galaxies contain supermassive black holes in their cores. If these black holes are actively feeding on the surrounding gas and dust, they form an accretion disk of infalling material where the tortured material glows in frequencies across the electromagnetic spectrum because of the extreme friction. The process results in 'bright ' black holes, unlike Sagittarius A* at the heart of the Milky Way, which is currently inactive. These bright black holes can outshine all the stars in the surrounding galaxy. Astronomers had suspected that the black holes co-evolve and grow with the surrounding galaxies, with new observations from the Euclid telescope providing evidence in support of this hypothesis. The researchers examined hundreds of thousands of galaxy mergers from up to ten billion years ago, and discovered that AGNs are between two and six times more common in...
A supernova is a violent explosion from a dying star, while a kilonova is produced by the merger between two neutron stars or a neutron star and a black hole. A team of astronomers may have discovered a superkilonova for the first time, where a supernova is followed by a kilonova. So far, scientists have discovered only one event that has been unambiguously confirmed to be a kilonova, detected by gravitational wave observatories and designated as GW170817. The new event, designated as AT2025ulz is a candidate, with a supernova blast hours before the kilonova. The initial eruption was detected by the Zwicky Transient Facility, that scans the skies for objects that appear to change positions or luminosities. The Keck Observatory turned towards the target, and captured the fading eruption, in red light, similar to the only confirmed kilonova detected eight years earlier. The red colours came from heavy elements such as gold, that block blue light, but let red light through. Days after...
Scientists from the Indian Institute of Astrophysics have reported the discovery of Poly Atomic Hydrocarbons (PAHs) in the debris disk surrounding a newborn star. The star, designated as T Chamaeleontis (T. Cha) is at a distance of 350 lightyears from the Earth in the small southern constellation of Chamaeleon. PAHs are flat molecules shaped like honeycomb, made up of carbon and hydrogen. These are believed to be the earliest precursor to the complex biochemistry as seen on Earth. PAHs are frequently discovered in stellar nurseries, vast clouds of gas and dust within which new stars are born. Discovering PAHs in the debris disk surrounding newborn stars is challenging because the gas and dust absorbs most of the ultraviolet radiation from the host star. The discovery was made using archival data from the James Webb Space Telescope, that is data not captured specifically for the study. The data was collected in 2022, when the collapse in the inner wall of the circumstellar disk...
NASA is building the first spacecraft specifically to identify large numbers of asteroids and comets that can impact the planet in the future. The Near Earth Object (NEO) Surveyor spacecraft will scan the Solar System using sensitive infrared detectors to track the most elusive objects in the neighbourhood of the Earth. Dark asteroids and comets do not reflect much of the light from the Sun in optical frequencies, but shed the excess heat, which is visible as infrared radiation. No large asteroids are comets are expected to strike the Earth for centuries into the future, but even smaller, denser objects can cause significant local damage on impact. Particularly problematic are asteroids that approach the Earth from the direction of the Sun. The light from the Sun saturates detectors in this direction, making in challenging to spot the dark rocks hidden in the glare of Sunlight. The spacecraft will use a large sunshade to protect the detectors from saturation, and block light from...
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