Latest news with #JeanSchneider
Express Tribune
28-03-2025
- Science
- Express Tribune
Will Blaze Star erupt today? Astronomers say signs point to a 2025 nova
Astronomers are closely monitoring T Coronae Borealis — also known as the Blaze Star — for a rare nova event expected to occur in 2025. Originally anticipated for March 27, the eruption has yet to happen. New estimates by Jean Schneider of the Paris Observatory suggest the explosion could occur as late as November 10, based on orbital data and the system's past behavior. The Blaze Star is a binary system located in the constellation Corona Borealis, around 3,000 light-years from Earth. It consists of a red giant and a white dwarf — a dense, Earth-sized stellar remnant. The white dwarf steadily siphons material from its companion until a thermonuclear eruption occurs. While the explosion is dramatic, the white dwarf remains intact and begins accumulating matter again, restarting the decades-long cycle. Historical eruptions were recorded in 1866 and 1946 — 80 years apart — which led astronomers to expect a third in the mid-2020s. Schneider's projections, published in the Research Notes of the American Astronomical Society (October 2024), aim to narrow the prediction to within a week or two, though he acknowledges that precise timing is still uncertain. Stargazers hoping to catch the celestial event should locate Corona Borealis in the night sky. The C-shaped constellation lies between the bright orange star Arcturus and the boxy shape of Hercules. When the nova occurs, the Blaze Star will briefly rival the constellation's brightest star, Alphecca, reaching an apparent magnitude of 2. Normally invisible to the naked eye, the Blaze Star will brighten by thousands of times over a few hours and fade after a few days. Skywatchers are advised to stay alert — the spectacle could begin at any time.
Yahoo
27-03-2025
- Science
- Yahoo
Hold onto your hats! Is the 'blaze star' T Corona Borealis about to go boom?
When you buy through links on our articles, Future and its syndication partners may earn a commission. A new set of predictions for the so-called "blaze star," T Corona Borealis suggests the star might go nova on either March 27, November 10, or June 25, 2026. However, other astronomers are skeptical about these predictions, which are based on an implied pattern in the explosive system's orbital configuration, "T Corona Borealis [T CrB] is a unique object that has fascinated amateur and professional astronomers for more than a century," Léa Planquart of the Institut d'Astronomie et d'Astrophysique at the Université Libre de Bruxelles in Belgium, told T CrB is a symbiotic binary, a vampire system in which a white dwarf is siphoning material from a red giant star. A white dwarf is the dense, compact core remnant of a once sun-like star, packing a mass equivalent to that of a star into a volume about the size of Earth. A red giant represents an earlier stage in a star's evolution, when a sun-like star starts to run out of its hydrogen fuel supply and begins to swell. Its distended atmosphere then becomes easy prey to the gravity of the far smaller, but denser, white dwarf. Material captured from the red giant forms a spiraling disk around the white dwarf, ultimately depositing that material onto the white dwarf's surface. Once enough material has built up, a thermonuclear explosion ignites. It does not destroy the white dwarf, but we can see the light of the explosion across thousands of light-years. We call this a nova, after the Latin for "new star." Typically, T CrB languishes at about magnitude +10, which means it is so faint that it can only be seen through moderate-aperture telescopes or large binoculars. However, when it goes nova, it brightens to naked-eye visibility, and hence briefly becomes seen as a "new star" in the night sky. T CrB is actually even more special than that, because it is one of only 11 known "recurrent" novas, which are seen to go nova repeatedly, with gaps of less than 100 years between explosions. Previously, on February 9, 1946 and May 12, 1866, the white dwarf in the T CrB system went nova. It also went nova around Christmastime in 1787, although the exact date isn't known, and there is also a suggestion that a nova connected to this star was seen sometime in the autumn night sky of 1217. Prior to the 1946 nova, T CrB brightened slightly in 1938, before dimming again just before going nova. The same pattern has also been seen in T CrB this time around, with it brightening by 0.7 magnitudes in 2015 before dimming again in 2023. This is why astronomers are anticipating a new nova. Jean Schneider of Paris Observatory, has also noticed what he believes to be a pattern between the timing of the T CrB nova events. The red giant and white dwarf take 227.5687 days to orbit one another, and Schneider believes that each nova takes place after a time equal to an exact whole number of orbits. In other words, something about the position of the white dwarf and the red giant is triggering the nova outbursts, he says. Yet, because their orbits are circular, no single position should have an effect. So, Schneider proposes the presence of a third object in the T CrB system on a wider, elliptical orbit. Every 79–80 years, he says the third object is close to the white dwarf, meaning that the white dwarf can feed off both the red giant and this hypothetical third object at the same time. This would enhance the rate of matter falling onto the white dwarf, creating the conditions for a nova. So far, this third object, if it exists, has remained undetected, but Schneider tells that "it could be detected by astrometry, radial velocity, direct imaging, a transit or microlensing." Indeed, Schneider wonders whether it hasn't already been detected but just not recognized. On April 21, 2016, the T CrB system suddenly increased in visual brightness by 0.5 magnitudes. "I have the following, qualitative interpretation, which is that before then, the third body was outside the pixel corresponding to the visual measurements," he said. In other words, the third object moved close enough to the other two components of the T CrB system that from our point of view it was sharing a pixel with them in images, adding its brightness to the combined light of the red giant and white dwarf. However, other astronomers are not yet convinced. Léa Planquart has studied T CrB and other recurrent novas, and in January published a paper describing the mass transfer between the red giant and the white dwarf based on radial velocity observations with the HERMES spectrograph on the 1.2-meter Mercator telescope at La Palma in Chile. Radial velocity here, for context, refers to the Doppler shifted motions of the individual stars and the matter being transferred between the red giant, what's known as the "accretion disk" and the white dwarf. "Jean Schneider has suggested the presence of a third companion in an eccentric orbit with a period of 80 years," Planquart told "Such additional orbital motion is, however, not detected in our decade-long radial-velocity monitoring." In other words, radial velocity measurements show no evidence for a third star, although Planquart cannot rule out a low-mass body such as a large exoplanet. Jeremy Shears, who is the Director of the British Astronomical Association's Variable Star Section, also has doubts. "Most astronomers are skeptical about this prediction, as am I," he told "The best thing to do is to keep watching every clear night." Should there be no third object, and if the pattern seen by Schneider in the dates of previous novas is just a coincidence, then what is happening to T CrB? Planquart's observations shed some light on the matter, particularly the brightening seen in 1938 and 2015, followed by a dimming, most recently seen in 2023. "We realized that from 2015 to 2023, the accretion disk around the white dwarf had reached its maximum extension and became hotter and more luminous, leading to increased brightness," Planquart said. This enhanced what Planquart calls "the vampirization effect," increasing the transfer of matter to the white dwarf in a "super-active phase." Then, in 2023, the accretion disk cooled back down again, resulting in the dimming, although matter continues to flow from the disk to the white dwarf at a slower rate. "It is likely that this enhanced activity is necessary to trigger the nova explosion, as it allows the material to accumulate more rapidly," said Planquart. Then, in 2023, the accretion disk cooled back down again, resulting in the dimming, although matter continues to flow from the disk to the white dwarf at a slower rate. However, the details are still somewhat unclear — what causes the state change in the accretion disk that leads to the super-active phase, and exactly what is happening on the surface of the white dwarf between the disk cooling again and the nova explosion? Although Schneider's exact date predictions may or may not come to pass, the pattern of the super-active phase followed by quiescence and dimming suggests that the nova is just around the corner. "We may expect to see the explosion in the coming months — or possibly next year," said Planquart. When that happens, what can we expect to see in the night sky? In 1946, T CrB reached magnitude +2, meaning it was easily visible to the naked eye, similar in brightness to the stars of the Big Dipper. Shears expects it to be just as bright this time around. T CrB is located in the constellation of Corona Borealis, the Northern Crown, which is currently visible in the night sky across the whole of the Northern Hemisphere and from as far south as South Africa and Australia (albeit low down in the sky from southerly locations). "At present T CrB is tenth magnitude, so it is only visible in giant binoculars," said Shears. "But when it rises [in brightness] it will become visible in standard binoculars and then the naked eye." And the rise in brightness will be rapid. "It's only a matter of a few hours for the rise to occur — precisely how many is not known as the rise has never been caught before," said Shears. "That's why it is so exciting. We hope that with so many observers this time around, we may indeed catch it as it awakes from its slumber." Indeed there will be many observers, as astronomers wait and watch to catch a glimpse of this rare nova and learn more about what is happening on the surface of this white dwarf when it hosts a giant thermonuclear explosion. "When it explodes, it will be one of the most extensively observed objects, targeted by telescopes worldwide," said Planquart. As for what the future holds for T CrB, an even larger explosion is on the horizon. The mass of the white dwarf in the T CrB system is 1.37 times the mass of our sun. This is very close to the Chandrasekhar limit, which is 1.44 solar masses, and is the point at which the thermonuclear detonation overcomes the white dwarf and blows it to smithereens as a Type Ia supernova. As it steadily steals mass from its companion red giant and grows in the process, it accelerates its own demise. Related Stories: — Is the 'Blaze Star' about to explode? If it does, here's where to look in March — 'Shocking' nova explosion of dead star was 100 times brighter than the sun — This astronomer found a sneaky extra star in James Webb Space Telescope data "As white dwarfs approach the Chandrasekhar limit their radius shrinks and their surface gravity is increased," Ken Hinkle, an astronomer at NOIRLab in Tucson, Arizona, told "This results in the short time between eruptions." As the white dwarf inches closer to the Chandrasekhar limit, the nova events will become more frequent, until one day … boom! But it will take hundreds of thousands, if not millions, of years for the white dwarf to get to that stage, so there's no rush to add it to your calendar. In the meantime, we shall keep watching the sky for its latest nova. Jean Schneider's paper was published in Research Notes of the AAS.
Yahoo
26-03-2025
- Science
- Yahoo
Get Ready to Watch This Star Explode
Keep your eyes peeled, because a dim star is about to quite literally go nuclear. And guess what? Its outburst will be visible to the naked eye, providing a once in a lifetime opportunity to witness a rare stellar explosion known as a nova. The star, T Coronae Borealis, is believed to erupt roughly every 80 years. After closely monitoring its activity, astronomer Jean Schneider at the Paris Observatory has calculated that it'll erupt again this Thursday, March 27, according to a paper he published with the American Astronomical Society last year. Prepare to give our scientific minds some leeway, however. T Coronae Borealis was predicted to go nova last year, after it exhibited dips in brightness, a telltale sign of an impending explosion, but the blast never came. Now, armed with more data, Schneider has narrowed the several-month window of previous predictions by others in the field down to a single day. If this week's a no-show, the next possible date this year will be November 10, 2025. Astronomers are excited, but stress that it's not guaranteed. "Since last September, detailed observations of the star have revealed variations that suggest the imminent arrival of this long-awaited explosion," Franck Marchis, a SETI Institute astronomer who was not involved in the work, recently told Forbes. "However, as the study is still theoretical, its conclusions remain uncertain." T Coronae Borealis, which is located just 3,000 light years away, is a binary star system comprising a white dwarf star and a red giant star. In the night sky, though, they appear as one. Tragically, they make for a toxic pairing. White dwarfs are the dense remnants of a massive star, while red giants are the slowly bloating forms of a more average Sun-like star long past its prime, having burned through all its fuel. Things get heated when they orbit too close to each other. Over time, the powerful gravitational pull of the white dwarf siphons huge amounts of mass from its stellar companion. Once enough of this stellar material, chiefly hydrogen, accumulates on the white dwarf's surface, it erupts in an epic thermonuclear explosion — a nova. The cosmic hydrogen bomb doesn't destroy the stars, however. They sustain the tensions in a cycle of eruptions. In T Coronae Borealis's case, the explosion will be powerful enough to elevate the star system from a measly magnitude +10 in brightness, at which it's invisible to the naked eye, to magnitude +2, according to NASA. That's bright enough to rival the North Star, Polaris. If you want to actually watch this nova in action, here's what you should know. After sunset, it'll appear as a new star in the constellation Corona Borealis, wedged between the constellations Hercules and Boötes. And don't fret if Thursday doesn't pan out. The nova should be visible to the unaided eye for several days, and over a week with binoculars. Happy hunting. More on stars: James Webb Space Telescope Captures Images of Individual Planets in Distant Star System
