Latest news with #PriyamDas
Yahoo
7 hours ago
- Science
- Yahoo
Astronomers Capture First-Ever Image of Star That Exploded Twice
For years, scientists have suspected that stars can meet their doom by a one-two punch of back-to-back explosions — but they've never seen visual evidence of this happening. That just changed. Astronomers using the Very Large Telescope in Chile have taken the first-ever image of a star that died in a stellar "double-detonation," leaving behind a spectacular supernova remnant. Their findings, published as a new study in the journal Nature Astronomy, deepen our understanding of the stellar evolution of burned-out stars called white dwarfs. "The explosions of white dwarfs play a crucial role in astronomy," lead author Priyam Das, a researcher at the University of New South Wales Canberra, Australia, said in a statement about the work. "Yet, despite their importance, the long-standing puzzle of the exact mechanism triggering their explosion remains unsolved." Once an exceptionally massive star — one at least several times heavier than the Sun — burns through all its fuel, it collapses under its own gravity in a powerful explosion known as a supernova. That's just one way supernovas can happen, though, and not all of them end the same. Some result in the star being completely obliterated, but others, if the star is heavy enough, can produce a super dense core called a neutron star, or even a black hole. The scene imaged by the VLT is the work of what's called a Type Ia supernova, produced by a low-mass star that exhausted all its fuel and left behind a remnant called a white dwarf. These objects are more compact and far denser than their original stars, endowing them with a wicked gravitational pull. In binary systems, this powerful gravity can lead to the white dwarf stripping matter off its stellar companion if their orbits are close enough. When enough of this stolen material accumulates on the surface of the white dwarf, reaching a point known as critical mass, it kickstarts a single but incredibly destructive thermonuclear explosion that wipes out both stars. That's the typical understanding. More recent research, though, has found evidence that some white dwarfs are battered by two explosions, not one, prior to winking out. In this scenario, astronomers believe that a white dwarf is swimming in a cloud of siphoned helium. This unstable helium cloud is the first to explode, precipitating a second blast in the core of the star. And bam: you have a two-fer supernova. Critically, this type of supernova occurs before the white dwarf reaches critical mass. Astronomers predicted that this double-detonation would produce a unique, visual signature in the form of two separate shells of calcium — and the new image bears this out. If you look closely, you can see that the calcium, depicted in blue, is indeed in a two-shell arrangement. This is a "clear indication that white dwarfs can explode well before they reach the famous Chandrasekhar mass limit, and that the 'double-detonation' mechanism does indeed occur in nature," said coauthor Ivo Seitenzahl, who conducted the observations while at the Heidelberg Institute for Theoretical Studies in Germany, in the statement. The work is invaluable for another reason. Type Ia explosions are considered "standard candles" that astronomers use as a measuring stick in the cosmos, because they shine at a consistent luminosity. Now we understand a little more about why that's the case. "Revealing the inner workings of such a spectacular cosmic explosion is incredibly rewarding," Das said. More on stars: Scientists Working to Decode Signal From Earliest Years of Universe
Yahoo
18 hours ago
- Science
- Yahoo
First-ever evidence of star 'double detonation' captured in stunning image
When you buy through links on our articles, Future and its syndication partners may earn a commission. For the first time, astronomers have captured stunning visual evidence of a star double-detonating itself to death. The twin eruption was discovered by scientists studying two concentric rings of calcium that surround SNR 0509-67.5, a remnant of a star that met its explosive demise in a type Ia supernova centuries ago. And the discovery isn't just a pretty picture. The researchers who made it say that much of our knowledge of how the universe expands — a major controversy in cosmology — depends on reliably measuring this type of supernova, which is also the primary source of iron throughout the cosmos. The scientists published their findings July 2 in the journal Nature Astronomy. For these reasons, "the explosions of white dwarfs play a crucial role in astronomy," study first author Priyam Das, a graduate student at the University of New South Wales Canberra in Australia, said in a statement. "Yet, despite their importance, the long-standing puzzle of the exact mechanism triggering their explosion remains unsolved." Type Ia supernovas occur when the material from one star is stolen by the husk of a co-orbiting dead star, known as a white dwarf, leading to a gigantic thermonuclear explosion. Yet not all the ways that white dwarves detonate are accounted for. Astronomers assume that these white dwarves steadily snatch their neighboring star's material, accumulating it until they reach a critical mass — the Chandrasekhar limit — and explode. But astronomers have found hints suggesting that this isn't the only way the husks blow up. Related: Supernova that lit up Earth's skies 843 years ago has a flowering 'zombie star' at its heart — and it's still exploding To search for direct evidence of a different ype of detonation, the researchers pointed the European Southern Observatory's Very Large Telescope at SNR 0509-67.5, a supernova that displays a clear shock wave shell pattern. Using the telescope's Multi Unit Spectroscopic Explorer instrument, they found two separate rings of calcium surrounding the remnants of the explosion. This is "a clear indication that white dwarfs can explode well before they reach the famous Chandrasekhar mass limit, and that the 'double-detonation' mechanism does indeed occur in nature," second-author Ivo Seitenzahl, a nuclear astrophysicist at the University of New South Wales Canberra, said in the statement. RELATED STORIES —Rare quadruple supernova on our 'cosmic doorstep' will shine brighter than the moon when it blows up in 23 billion years —Weird repeating explosion beyond the Milky Way is one of the hottest blasts scientists have ever seen —A nearby supernova nearly blew our solar system to bits 4 billion years ago, new research suggests The researchers propose that this white dwarf exploded by blanketing itself in stolen helium from its neighbor that then ignited, sending a shockwave inwards that caused the dead star's core to blow in a second, larger, explosion. Studying this dual detonation could have important implications for our wider understanding of the universe. No matter which way they occur, type Ia supernovas are thought to always explode with the same brightness, making them "standard candles" from which astronomers can measure far-off distances and calculate the expansion rate of our universe. In recent years, contesting measurements of this expansion rate, known as the Hubble constant, have sparked a major crisis in cosmology. "This tangible evidence of a double-detonation not only contributes towards solving a long-standing mystery, but also offers a visual spectacle," Das said. "Revealing the inner workings of such a spectacular cosmic explosion is incredibly rewarding."
Yahoo
a day ago
- Science
- Yahoo
Astronomers capture incredible 1st image of a dead star that exploded twice. How did it happen?
When you buy through links on our articles, Future and its syndication partners may earn a commission. You may only live once, but some stars die twice. Astronomers have now discovered the first visual evidence of such a stellar event, a dead star that underwent a so-called "double-detonation." This could indicate that some stars could go supernova without reaching the so-called Chandrasekhar limit, the minimum mass that a star needs to go supernova. Using the Very Large Telescope (VLT) and its Multi Unit Spectroscopic Explorer (MUSE) instrument, the team zoomed in on the centuries-old remains of supernova SNR 0509-67.5 located 60,000 light-years away in the constellation Dorado. This investigation revealed structures within this explosive wreckage that indicate its progenitor star exploded not once but twice. Said star was a white dwarf, the type of stellar remnant that forms when a star with a mass similar to that of the sun runs out of fuel for nuclear fusion. The types of supernova explosions that white dwarfs undergo, Type Ia supernovas, are important to astronomers because they can be used to measure cosmic distances because their light output is so uniform. Thus, astronomers often refer to them as "standard candles."The first visual evidence of a double detonation white dwarf reveals hidden depths to these important stellar events, scientists say. "The explosions of white dwarfs play a crucial role in astronomy," team leader and University of New South Wales researcher Priyam Das said in a statement. "Yet, despite their importance, the long-standing puzzle of the exact mechanism triggering their explosion remains unsolved." Scientists agree that the genesis of Type Ia supernovas is binary systems of two stars in which one becomes a white dwarf. If this dead star orbits close enough to its living stellar companion, or if that companion swells up, then the white dwarf becomes a stellar vampire, greedily stripping material from its companion or "donor" star. This continues until the piling up stolen material has added so much mass to the white dwarf that the stellar remnant crosses the so-called Chandrasekhar limit, which is about 1.4 times the mass of the sun. Hence, this cosmic vampire white dwarf explodes in a Type Ia supernova. It is believed that in most cases, the eruption completely destroys the white dwarf. But for some time, astronomers have suspected there may be more to the story. Maybe white dwarfs can experience a second explosion. This research confirms that at least some white dwarfs experience double-detonations. The question is: why? Theory behind double-detonations suggests that in these cases, as white dwarfs are stripping material from a donor star, they wrap themselves in a blanket of stolen helium. This envelope becomes unstable and eventually ignites, triggering the first detonation. The initial explosion generates a shockwave that ripples inwards, eventually striking the core of the white dwarf, triggering a second detonation, the actual supernova. The significance of this to our understanding of Type Ia white dwarf supernovas is that it can occur well before a dead star swells beyond the Chandrasekhar limit. Recently, scientists determined that this double-detonation process would imprint a distinctive "fingerprint" with supernova wreckage. This should be present long after the supernova ripped its progenitor star apart. That fingerprint is now visually confirmed as being present in the wreckage of SNR 0509-67.5, supernova wreckage in the Large Magellanic Cloud first detected in 2004 and believed to be around 400 years old as we see it. Related Stories: — 'Vampire stars' explode after eating too much — AI could help reveal why — Supernova explosion's weird leftovers may contain a super-dense star — Peer inside remnants of an 800-year-old supernova and see a 'zombie' star Beyond being an important discovery for our scientific understanding of these events and solving a lingering mystery about the evolution of white dwarfs, the observation of SNR 0509-67.5 has provided astronomy lovers with some stunning eye-candy. "This tangible evidence of a double-detonation not only contributes towards solving a long-standing mystery, but also offers a visual spectacle," Das concluded. The team's research was published on Wednesday (July 2) in the journal Nature Astronomy
Ammon
2 days ago
- Science
- Ammon
Astronomers get picture of aftermath of a star's double detonation
Ammon News - The explosion of a star, called a supernova, is an immensely violent event. It usually involves a star more than eight times the mass of our sun that exhausts its nuclear fuel and undergoes a core collapse, triggering a single powerful explosion. But a rarer kind of supernova involves a different type of star - a stellar ember called a white dwarf - and a double detonation. Researchers have obtained photographic evidence of this type of supernova for the first time, using the European Southern Observatory's Chile-based Very Large Telescope. The back-to-back explosions obliterated a white dwarf that had a mass roughly equal to the sun and was located about 160,000 light‑years from Earth in the direction of the constellation Dorado in a galaxy near the Milky Way called the Large Magellanic Cloud. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). The image shows the scene of the explosion roughly 300 years after it occurred, with two concentric shells of the element calcium moving outward. This type of explosion, called a Type Ia supernova, would have involved the interaction between a white dwarf and a closely orbiting companion star - either another white dwarf or an unusual star rich in helium - in what is called a binary system. The primary white dwarf through its gravitational pull would begin to siphon helium from its companion. The helium on the white dwarf's surface at some point would become so hot and dense that it would detonate, producing a shockwave that would compress and ignite the star's underlying core and trigger a second detonation. "Nothing remains. The white dwarf is completely disrupted," said Priyam Das, a doctoral student in astrophysics at the University of New South Wales Canberra in Australia, lead author of the study published on Wednesday in the journal Nature Astronomy, opens new tab. "The time delay between the two detonations is essentially set by the time it takes the helium detonation to travel from one pole of the star all the way around to the other. It's only about two seconds," said astrophysicist and study co-author Ivo Seitenzahl, a visiting scientist at the Australian National University in Canberra. In the more common type of supernova, a remnant of the massive exploded star is left behind in the form of a dense neutron star or a black hole. The researchers used the Very Large Telescope's Multi-Unit Spectroscopic Explorer, or MUSE, instrument to map the distribution of different chemical elements in the supernova aftermath. Calcium is seen in blue in the image - an outer ring caused by the first detonation and an inner ring by the second. These two calcium shells represent "the perfect smoking-gun evidence of the double-detonation mechanism," Das said. "We can call this forensic astronomy - my made-up term - since we are studying the dead remains of stars to understand what caused the death," Das said. Stars with up to eight times the mass of our sun appear destined to become a white dwarf. They eventually burn up all the hydrogen they use as fuel. Gravity then causes them to collapse and blow off their outer layers in a "red giant" stage, eventually leaving behind a compact core - the white dwarf. The vast majority of these do not explode as supernovas. While scientists knew of the existence of Type Ia supernovas, there had been no clear visual evidence of such a double detonation until now. Type Ia supernovas are important in terms of celestial chemistry in that they forge heavier elements such as calcium, sulfur and iron. "This is essential for understanding galactic chemical evolution including the building blocks of planets and life," Das said. A shell of sulfur also was seen in the new observations of the supernova aftermath. Iron is a crucial part of Earth's planetary composition and, of course, a component of human red blood cells. In addition to its scientific importance, the image offers aesthetic value. "It's beautiful," Seitenzahl said. "We are seeing the birth process of elements in the death of a star. The Big Bang only made hydrogen and helium and lithium. Here we see how calcium, sulfur or iron are made and dispersed back into the host galaxy, a cosmic cycle of matter." Reuters
India Today
2 days ago
- Science
- India Today
Astronomers get first visual of a sun dying by detonating twice
In a first-of-its-kind observation, astronomers have obtained the visual evidence of a star dying by double detonation, when stars are known to disappear by giant European Southern Observatory's Very Large Telescope has studied the centuries-old remains of supernova SNR 0509-67.5 to confirm the patterns of dual back-to-back explosions obliterated a white dwarf that had a mass roughly equal to the sun and was located about 1,60,000 lightyears from Earth in the direction of the constellation Dorado in a galaxy near the Milky Way called the Large Magellanic Cloud. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). This image shows the distribution of calcium in the supernova remnant SNR 0509-67.5. (Photo: ESO) advertisement "The explosions of white dwarfs play a crucial role in astronomy. Yet, despite their importance, the long-standing puzzle of the exact mechanism triggering their explosion remains unsolved," Priyam Das, a PhD student at the University of New South Wales Canberra, who led the study, details of the finding were published in the journal Nature Astronomy. Astronomers had long been suspecting that some stars do meet their end of life with a dual detonation and new images prove their hunch was right: at least some Type Ia supernovae explode through a 'double-detonation' mechanism instead."The time delay between the two detonations is essentially set by the time it takes the helium detonation to travel from one pole of the star all the way around to the other. It's only about two seconds," said astrophysicist and study co-author Ivo Seitenzahl, a visiting scientist at the Australian National University in Canberra. This image marks the position on the sky of the supernova remnant SNR 0509-67.5. (Photo: ESO) advertisementIn the more common type of supernova, a remnant of the massive exploded star is left behind in the form of a dense neutron star or a black hole.'This tangible evidence of a double-detonation not only contributes towards solving a long-standing mystery, but also offers a visual spectacle,' Priyam says, describing the 'beautifully layered structure' that a supernova creates. For him, 'revealing the inner workings of such a spectacular cosmic explosion is incredibly rewarding.'- EndsTrending Reel
