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Yahoo
22-05-2025
- Science
- Yahoo
Astronomers spy puzzlingly 'perfect' cosmic orb with unknown size and location
When you buy through links on our articles, Future and its syndication partners may earn a commission. Astronomers have discovered the eerie remains of a supernova with an almost perfect spherical shape glowing faintly on the outskirts of the Milky Way. However, they are unsure exactly how large and how far away the ghostly orb is — or how it got its unusually symmetrical shape. The scientists named the object G305.4–2.2, or Telios — Greek for "perfect." Telios was spotted in radio images captured by the Australian Square Kilometre Array Pathfinder (ASKAP) telescope in Western Australia for the Evolutionary Map of the Universe project. It is a supernova remnant (SNR) — an expanding cloud of gas and radiation left over from an exploded star. Most SNRs are at least vaguely spherical due to how supernovas explode outward in all directions, although some have more unorthodox shapes, as they dissipate over time or get bent out of shape by other explosions or stellar winds. However, it is rare to find remnants that appear to have almost no imperfections. The researchers described the SNR in a new study, uploaded May 7 to the pre-print server arXiv and accepted for future publication in the journal Publications of the Astronomical Society of Australia. "This object [Telios] displays a remarkable circular symmetry in shape, making it one of the most circular galactic SNRs known," the researchers wrote in the paper. Related: Rare quadruple supernova on our 'cosmic doorstep' will shine brighter than the moon when it blows up in 23 billion years Telios is also unusual for its extremely low brightness compared with most other SNRs, which suggests that it is either really young or really old. Based on its perfect shape, it is most likely to be the former because most SNRs lose their shape as they age, the researchers wrote. The low brightness makes it hard to determine Telios' distance from Earth, which also raises uncertainty about its size. The researchers believe it could be anywhere from 7,170 to 25,100 light-years from our planet, meaning it could span anywhere from 45.6 to 156.5 light-years across — dozens of times larger than our solar system. The object is located below the galactic plane — the disk of matter swirling around the Milky Way's supermassive black hole, where most objects in the galaxy, including the solar system, are situated. Its unusual location adds to the uncertainty about its distance and size. But despite being outside the galactic plane, Telios is still part of the Milky Way. Orb-like SNRs are very rare. However, a handful have been discovered before in dwarf galaxies that orbit the Milky Way. These include SN1987A and MC SNR J0509–673, located in the Small Magellanic Cloud (SMC); and SNR J0624–6948, which was discovered in the Large Magellanic Cloud (LMC) earlier this year. RELATED STORIES —Supernova that lit up Earth's skies 843 years ago has a flowering 'zombie star' at its heart — and it's still exploding —Strange 'reverse shock wave' supernova is exploding in the wrong direction —Scientists find evidence of 'supernova graveyard' at the bottom of the sea — and possibly on the surface of the moon There are two ways in which these perfect SNRs form: via a core-collapse supernova, where massive red giant stars implode, generating a shockwave that in turn pushes its matter outward; or via a Type Ia supernova, where smaller stars explode in much more violent explosions, which astronomers use to study some of cosmology's biggest mysteries. The researchers believe that a Type Ia supernova was the more likely origin for Telios because red giants are much less common outside the galactic plane. However, it is hard to tell for sure because they cannot identify the remnant's progenitor — the shriveled husk of the exploded star that usually lurks at the heart of SNRs. "While we deem the Type Ia scenario the most likely, we note that no direct evidence is available to definitively confirm any scenario and new sensitive and high-resolution observations of this object are needed," the researchers wrote.
Yahoo
20-05-2025
- Science
- Yahoo
Astronomers Baffled by a Suspicious, Perfectly Round Sphere in Our Galaxy
Today, in questions you didn't know you needed the answer to: Is there such a thing as a perfect ball? And if there were, would it contain the secrets of the universe? To wit, a spherical object lurking in our galaxy is so perfectly round that astronomers can't explain how it was formed. Dubbed "Teleios" after the Greek word for "perfect," the object is what's known as a supernova remnant (SNR), a glowing cloud of hot gases and other material left behind after a massive star dies in a powerful explosion called a supernova. And it's definitely earned its nickname. According to the astronomers' findings, as reported in a pre-print study accepted for publication in Publications of the Astronomical Society of Australia, this is one of the most circular galactic SNRs ever found. "The shape indicates Teleios has remained relatively untouched by its environment," said lead author Miroslav Filipovic, an astronomer at Western Sydney University, in an essay for The Conversation written with his colleagues earlier this year. "This presents us with an opportunity to make inferences about the initial supernova explosion, providing rare insight into one of the most energetic events in the universe." When a star goes supernova, it blasts all that stellar material into space in a tremendous release of energy bright enough to momentarily outshine even entire galaxies. The astronomers believe that Teleios is the result of a rare type of explosion — we're talking happening only once every 500 years in the Milky Way rare — called a type Ia supernova that occurs in binary star systems. When a smaller but far denser white dwarf siphons enough matter from its companion star whose orbit has crept too close, the stolen stellar material detonates in an epic thermonuclear explosion that obliterates both the stars. For something so symmetrical to emerge out of an event so violent is unusual, to put it mildly. "The supernova remnant will be deformed by its environment over time. If one side of the explosion slams into an interstellar cloud, we'll see a squashed shape," explained Filipovic in the essay. "So, a near-perfect circle in a messy universe is a special find." Teleios was uncovered as part of the Evolutionary Map of the Universe (EMU) survey using the Australian Square Kilometer Array Pathfinder (ASKAP), an enormous radio telescope that's proving to be a powerful tool for finding SNRs that aren't visible in other wavelengths. Teleios, exclusively seen at radio-continuum frequencies, is one of them. Along with its perfect shape, it has one of the lowest surface brightnesses among all known galactic SNRs. The astronomers estimate that Teleios lies at a distance of either 2.2 or 7.7 kiloparsecs away (or approximately 7,100 or 25,100 light years). The uncertainty surrounding its distance means its age and size are hard to pin down, too. It's either on the younger side at less than 1,000 years old, or much older at over 10,000 years old. Likewise, it could be as small as 46 light years across, or as large as 157 light years. In any case, their findings place Teleios at a stage of its evolution called the Sedov-Taylor phase, during which the expansion of the SNR first begins to slow down, as it sweeps up additional mass from the interstellar medium of space. There's a catch, though: this process should produce detectable x-ray emissions, but the astronomers haven't see any. Maybe, the astronomers explored, Teleios is actually the remnant of an even rarer type of Ia supernova: a type Iax, in which the white dwarf partially survives as "zombie star." In that case, Teleios might be much closer at less than 3,200 light years away while being about 10.7 light years across. No hard answer, however, can be made from the data we have now. But this is just the beginning, and the astronomers are optimistic that more detailed observations in the future will one day help put this mystery to bed. More on stars: NASA's James Webb Telescope Just Found Frozen Water Around Another Star
