Latest news with #CharlesKilpatrick
Yahoo
15-03-2025
- Science
- Yahoo
Mysterious Signal Coming From a Dead Star and Its Companion
When these stars dance, they make their own music. Astronomers have tracked down the source of a mysterious radio signal from deep space repeating every two hours. Intriguingly, it's a pair of stars in such a tight orbit that their magnetic fields regularly bump into each other — and it's this bodily percussion that appears to be blasting out the radio emissions we're picking up on Earth, roughly 1,600 light years away. The findings on the binary system, published in a new study in the journal Nature Astronomy, shine a much-needed light on a new class of cosmic signal known as long-period radio transients. These extremely rare repeating radio pulses are similar to what's emitted by rapidly rotating stars called pulsars, whose signals we see every time their poles turn towards Earth, but repeat every few minutes — or even hours — compared to the latter's sub-second intervals. Simply put, it would be impossible for pulsars to rotate slowly enough to produce long period transients, and astronomers have searched far and wide for alternative sources. "Now, we know at least some long-period radio transients come from binaries," said study coauthor Charles Kilpatrick, an astrophysicist at Northwestern University, in a statement about the work. "We hope this motivates radio astronomers to localize new classes of sources that might arise from neutron star or magnetar binaries." The radio pulses — seven of them — were first discovered last year using the Low Frequency Array radio telescope in Europe. "Taking a closer look at the timing of these pulses, we found that they arrive every two hours," wrote lead author Iris de Ruiter at the University of Sydney in an essay for The Conversation. "We compared the location of the radio pulses to optical catalogues, which list stars and galaxies that telescopes have observed in visible light. And there it was – we found there was a faint red star exactly at the location of our radio pulses." The faint star is a red dwarf — a small but extremely ubiquitous main sequence star. But it couldn't produce the signal on its own, de Ruiter wrote. There had to be a companion; binary systems, after all, are common. To find the hidden partner, the astronomers looked at the spectra of light coming from the red dwarf. They found that the light would intermittently shift to shorter and longer wavelengths, a sign that the star is moving back and forth. And that could only mean that it's locked in orbit with another object. That turned out to be a stellar remnant known as a white dwarf. White dwarfs are sometimes referred to as "dead stars" because they're the leftover, hot core of a massive star that exploded in a supernova. Still, de Ruiter says we're just scratching the surface of long period transients, because not all of them will come from binary systems like this one. "The current landscape of long period transients is sparse. We need to find more of them to get a full understanding of these mysterious objects and how they work," de Ruiter wrote in The Conversation. "However, we now know that white dwarfs, with a little help from a stellar friend, can produce radio pulses just as bright as neutron stars." More on stars: Scientists Realize They Witnessed the Last Gasp of a Planet as It Met a Horrible Fate
Yahoo
14-03-2025
- Science
- Yahoo
Astronomers crack the case of a mysterious deep space radio signal that repeats every 2 hours
When you buy through links on our articles, Future and its syndication partners may earn a commission. Astronomers have cracked the case of a mysterious repeating radio signal that has been a mystery since it was uncovered last year. The team tracked the signal back to a strange binary system containing a dead star or "white dwarf" and a red dwarf stellar companion. The radio pulse repeats every 2 hours and was first detected a decade ago. It came from the direction of the Big Dipper. This new research indicates that the cause of this repeating radio signal is the magnetic fields of the white dwarf and its red dwarf stellar companion slamming together in this tight binary, designated ILTJ1101. Previously, long-period radio bursts like this one had only been traced back to neutron stars, meaning this work puts an entirely new spin on their origins."There are several highly magnetized neutron stars, or magnetars, that are known to exhibit radio pulses with a period of a few seconds," team member and Northwestern astrophysicist Charles Kilpatrick said in a statement. "Some astrophysicists also have argued that sources might emit pulses at regular time intervals because they are spinning, so we only see the radio emission when the source is rotated toward us. "Now, we know at least some long-period radio transients come from binaries. We hope this motivates radio astronomers to localize new classes of sources that might arise from neutron star or magnetar binaries." The team's research was published in the journal Nature Astronomy on Wednesday (March 12). Team leader Iris de Ruiter from the University of Sydney in Australia first discovered the signal in 2024 when she was searching through archival data collected by the Low Frequency Array (LOFAR). LOFAR is the largest radio telescope operating at the lowest frequencies that can be detected from pulse first appeared in LOFAR data in 2015, and after finding its first instance, de Ruiter found six more pulses from the same source. These flashes of radio waves can last anywhere from several seconds to a few minutes. Despite the difference in duration, the pulses repeat regularly, once every two hours. The pulses have some similarities with a cosmic phenomenon called "fast radio bursts" or FRBs," but are much rarer. "The radio pulses are very similar to FRBs, but they each have different lengths," Kilpatrick said. "The pulses have much lower energies than FRBs and usually last for several seconds, as opposed to FRBs, which last milliseconds. "There's still a major question of whether there's a continuum of objects between long-period radio transients and FRBs, or if they are distinct populations." The team wanted to know what the source of these regular radio pulses is, so they performed follow-up investigations with the Multiple Mirror Telescope (MMT) Observatory in Arizona and the McDonald Observatory in Texas. This revealed the origin of the pulses was two stars located around 1,600 light-years from Earth that are pulsing in unison. The two stars whip around each other once every 125.5 minutes. The researchers then further investigated the system for a full two-hour-long cycle using MMT discovering the true nature of this system. The team's detailed observations allowed them to track the system's movement in detail while gaining information from the red dwarf star by breaking its light down into different wavelengths or spectra. "The spectroscopic lines in these data allowed us to determine that the red dwarf is moving back and forth very rapidly with exactly the same two-hour period as the radio pulses," Kilpatrick said. "That is convincing evidence that the red dwarf is in a binary system." This back-and-forth rocking of this star seems to be the result of a barely visible companion in ILTJ1101 gravitationally tugging on it. The variation of the motion revealed to the team the mass of this very faint companion. This allowed them to determine it is a white dwarf, a stellar remnant that is created when a star with around the mass of the sun reaches the end of its life and its collapses while its outer layers are shrugged off. "In almost every scenario, its mass and the fact that it is too faint to see means it must be a white dwarf," Kilpatrick explained. "This confirms the leading hypothesis for the white dwarf binary origin and is the first direct evidence we have for the progenitor systems of long-period radio transients." Related Stories: — Astronomers discover record haul of 25 new repeating 'fast radio bursts' — Record-breaking radio burst could help us find the universe's missing matter — Shortest 'fast radio bursts' ever discovered last only 1 millionth of a second Astronomers are now planning to study the high-energy ultraviolet emissions of ILTJ1101. This could reveal the temperature of the white dwarf and additional details of red dwarf/white dwarf binaries like this one. "It was especially cool to add new pieces to the puzzle,' team leader de Ruiter said. "We worked with experts from all kinds of astronomical disciplines. "With different techniques and observations, we got a little closer to the solution step by step.'
