Chorus waves are mysterious, chirping signals produced by spiraling plasma inside our planet's magnetic field. But a new detection suggests scientists may understand less about them than first thought.
Scientists have detected strange chirping waves — which resemble the dawn chorus of birds — thousands of miles from Earth, and they could pose big problems for future spaceflight.

Chorus waves, named because of their resemblance to birdsong when converted to audio signals, are perturbations in Earth's electromagnetic field capable of accelerating particles to potentially deadly speeds for spacecraft and astronauts.

Yet while these mysterious waves have been spotted coming from Earth and other planets since the 1960s, scientists previously assumed they only occurred nearby.

Now, in a discovery that challenges existing theories, a new team of researchers has spotted the waves at a distance of 100,000 miles (165,000 kilometers) from Earth, roughly three times further than they were detected before. The researchers published their findings Jan 22. in the journal Nature.

Chorus waves (or whistler-mode chorus waves) are bursts of energy lasting just a few tenths of a second that ping across Earth's magnetosphere, the magnetic field that envelops our planet. The waves were first detected by World War I radio operators who heard them while listening for enemy signals.

In the decades since, chorus waves have been picked up by radio receivers, as well as by NASA's Van Allen Probe spacecraft, which detected the chirrups coming from Earth's radiation belts. The waves have also been spotted surrounding Mercury, Jupiter, Saturn, Uranus and Neptune (all planets with global magnetic fields) as well as Mars and Venus, which do not have magnetic fields.

The new ability to pinpoint sources of fast radio bursts places one recent burst in a surprising location.
Astronomer Calvin Leung was excited last summer to crunch data from a newly commissioned radio telescope to precisely pinpoint the origin of repeated bursts of intense radio waves — so-called fast radio bursts (FRBs) — emanating from somewhere in the northern constellation Ursa Minor.

Leung, a Miller Postdoctoral Fellowship recipient at the University of California, Berkeley, hopes eventually to understand the origins of these mysterious bursts and use them as probes to trace the large-scale structure of the universe, a key to its origin and evolution. He had written most of the computer code that allowed him and his colleagues to combine data from several telescopes to triangulate the position of a burst to within a hair's width at arm's length.

The excitement turned to perplexity when his collaborators on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) turned optical telescopes on the spot and discovered that the source was in the distant outskirts of a long-dead elliptical galaxy that by all rights should not contain the kind of star thought to produce these bursts.

Instead of finding an expected "magnetar" — a highly magnetized, spinning neutron star left over from the core collapse of a young, massive star — "now the question was: How are you going to explain the presence of a magnetar inside this old, dead galaxy?" Leung said.

The young stellar remnants that theorists think produce these millisecond bursts of radio waves should have disappeared long ago in the 11.3-billion-year-old galaxy, located 2 billion light years from Earth and weighing more than 100 billion times the mass of the sun.

This NASA/ESA Hubble Space Telescope Picture of the Week features the galaxy LEDA 22057, which is located about 650 million light-years away in the constellation Gemini. Like the subject of a previous Picture of the Week, LEDA 22057 is the site of a supernova explosion.

This particular supernova, named SN 2024PI, was discovered by an automated survey in January 2024. The survey covers the entire northern half of the night sky every two days and has cataloged more than 10,000 supernovae.

The supernova is visible in the image: Located just down and to the right of the galactic nucleus, the pale blue dot of SN 2024PI stands out against the galaxy's ghostly spiral arms. This image was taken about a month and a half after the supernova was discovered, so the supernova is seen here many times fainter than its maximum brilliance.

Also known as Virgo A or NGC 4486, M87 is the brightest object in the Virgo cluster of galaxies, the largest gravitationally bound type of structure in the universe. It came to fame in April 2019 after scientists from EHT released the first image of a black hole in its center. Led by the EHT multi wavelength working group, a study published in Astronomy and Astrophysics Journal presents the data from the second EHT observational campaign conducted in April 2018, involving over 25 terrestrial and orbital telescopes. The authors report the first observation of a high-energy gamma-ray flare in over a decade from the supermassive black hole M87, based on nearly simultaneous spectra of the galaxy spanning the broadest wavelength range ever collected.

"We were lucky to detect a gamma-ray flare from M87 during this Event Horizon Telescope's multi-wavelength campaign. This marks the first gamma-ray flaring event observed in this source in over a decade, allowing us to precisely constrain the size of the region responsible for the observed gamma-ray emission. Observations — both recent ones with a more sensitive EHT array and those planned for the coming years — will provide invaluable insights and an extraordinary opportunity to study the physics surrounding M87's supermassive black hole. These efforts promise to shed light on the disk-jet connection and uncover the origins and mechanisms behind the gamma-ray photon emission." says Giacomo Principe, one of the paper coordinators, a researcher at the University of Trieste associated with INAF and INFN. The article has been accepted for publication in Astronomy & Astrophysics.

The relativistic jet examined by the researchers is surprising in its extent, reaching sizes that exceed the black hole's event horizon by tens of millions of times (7 orders of magnitude) - akin to the difference between the size of a bacterium and the largest known blue whale.

The X-ray outburst from the nova, observed by the Neil Gehrels Swift Observatory, is one of the brightest ever produced by a white dwarf star.
A rare, extremely luminous X-ray outburst has been observed in the Small Magellanic Cloud, a dwarf galaxy that is a close neighbor of our own Milky Way galaxy. The observations, made by the Neil Gehrels Swift Observatory and other telescopes, were described by an international team of astronomers led Penn State scientists on the Swift team. The researchers attribute the outburst to a nova eruption produced by a white dwarf binary star system. The researchers attributed the outburst to one of the most luminous nova eruptions ever produced by a white dwarf binary star system.

The observations were described in a paper recently published in the Monthly Notices of the Royal Astronomical Society.

"This is only the second time that we have observed such a bright outburst from this type of white dwarf binary system," said Thomas Gaudin, a graduate student at Penn State and the first author of the paper. "We hope that this event will provide more insight into how these outbursts are produced and help us to better understand this mysterious class of binary."

The system that produced this outburst is referred to as CXOU J005245.0-722844. It was recently identified by members of the Einstein Probe team and confirmed by the Swift team as the seventh-known example of a Be/White Dwarf X-ray binary. Be/White Dwarf binaries are binary systems in which a white dwarf star orbits a hot young star surrounded by a disk of stellar material. Astronomers expect these binaries to be commonly observed, Gaudin said, and the lack of known examples is a mystery.

The Northern Lights have splashed vivid colour across UK night skies once again, with stunning images captured all across the country.

The lights, also known as aurora borealis, were expected to be seen only as far south as the Midlands, but on Wednesday night, according to BBC Weather was the strongest and most widespread showing of the phenomenon in the UK since May.

As solar activity weakens, it might still be possible for those in some Northern areas to see the lights on Friday, but elsewhere, the chances are low.

The James Webb Space Telescope has zoomed in on an ancient supernova, revealing fresh evidence that a crisis in cosmology called the Hubble tension isn't going anywhere soon.
The James Webb Space Telescope (JWST) has discovered yet another troubling sign that there's something very wrong with our model of the universe.

Depending on which part of the universe astronomers measure, the cosmos seems to be growing at different rates — a problem scientists call the Hubble tension. Measurements taken from the distant, early universe show that the expansion rate, called the Hubble constant, closely matches our best current model of the universe, while those taken nearer to Earth threaten to break it.

Now, a new study using the gravitationally-warped light of a 10.2 billion light-year distant supernova has revealed that the mystery could be here to stay. The researchers released their findings in a series of papers in The Astrophysical Journal. The Hubble tension calculations have also been accepted for publication in the journal, and are posted in a paper on the pre-print database arXiv.

"Our team's results are impactful: The Hubble constant value matches other measurements in the local universe, and is somewhat in tension with values obtained when the universe was young," co-author Brenda Frye, an associate professor of astronomy at the University of Arizona said in a statement.

New analysis of Betelgeuse's brightness variations and other data points to a small, close companion for this giant star.

Astronomers may have discovered a companion star orbiting around Betelgeuse, one of the brightest and most famous stars in the sky. The gravity of this partner could help explain the way Betelgeuse regularly brightens and dims. What's more, Betelgeuse could consume this companion in as little as 10,000 years.

Betelgeuse is one of the best studied stars, with detailed records stretching back more than a century. Thanks to these observations, astronomers know that Betelgeuse is highly variable. The star pulsates violently, which alters its brightness in a pattern that repeats roughly every 400 days. However, there is a second pattern of brightness variation lasting approximately 2,000 days. This second pattern also appears in measurements of the star's motions toward and away from Earth (its radial velocity), which suggest that Betelgeuse is slowly rocking back and forth. As early as 1908, astronomers were speculating that this was due to an unseen companion star pulling the gravitational strings. Except no-one has ever found evidence of one — until now, perhaps.

A team led by Morgan MacLeod (Center for Astrophysics, Harvard & Smithsonian) has collated and analysed more than a century's worth of data, including measurements of Betelgeuse's radial velocity, brightness (photometry), and position on the sky (astrometry). The researchers conclude that each of these data sets could be explained if Betelgeuse has what they whimsically refer to as "a little friend." Their paper is available on the arXiv preprint server.

To explain the data, the companion would need to be less massive than the Sun and would take 2,110 days to orbit Betelgeuse from a distance equivalent to the giant star's width. (Betelgeuse is about as wide as Jupiter is far from the Sun.) "It was very surprising," says MacLeod. "It's kind of hidden right there in plain sight."

"The dataset that the authors put forward is rather compelling," says Rene Oudmaijer (Royal Observatory of Belgium), who was not involved in the research. "The caveat is of course that the companion itself is not directly detected, so there is still room for doubt."

Using a new method exploiting the capabilities of the Multi Unit Spectroscopic Explorer (MUSE), astronomers have detected 307 new supernova remnants, including seven rare oxygen-rich ones. The finding was presented in a research paper published September 10 on the preprint server arXiv.

Supernova remnants (SNRs) are diffuse, expanding structures resulting from a supernova explosion. They contain ejected material expanding from the explosion and other interstellar material that has been swept up by the passage of the shockwave from the exploded star.

Some supernova remnants showcase strong visible light oxygen emission, and due to that, are known as oxygen-rich SNRs. However, oxygen-rich SNRs are rarely found, as to date, only eight such objects have been identified in our galaxy and in the Magellanic Clouds. Moreover, the nature of these SNRs and their connection to specific supernovae (SNe) is still not well understood.

Now, a team of astronomers led by Timo Kravtsov of the European Southern Observatory (ESO) in Chile reports new findings that could advance our knowledge about oxygen-rich supernova remnants. By employing a new method of SNR detection, they managed to discover hundreds of new remnants with MUSE mounted on ESO's Very Large Telescope (VLT), including those exhibiting oxygen-emission.

"We present a new method to detect SNRs exploiting the capabilities of modern visible-light integral-field units based on the shapes of the SNR emission lines," the researchers explained.

If you travel far enough away from the Sun, the Solar System becomes a lot more populated.

Out past the orbit of Neptune lies the Kuiper Belt, a vast, ring-shaped field of icy rocks. This is where Pluto resides, and Arrokoth, and countless other small objects in the cold and the dark.

These are known as Kuiper Belt objects or KBOs, and astronomers have just found hints of an unexpected rise in their density, between 70 and 90 astronomical units from the Sun, separated by a large, practically empty gap between it and an inner population of KBOs closer to the Sun.

It seems, almost, like there are two Kuiper Belts, or at least two components - something nobody was expecting to find.

"If this is confirmed, it would be a major discovery," says planetary scientist Fumi Yoshida of the University of Occupational and Environmental Health Sciences and Chiba Institute of Technology in Japan.

"The primordial solar nebula was much larger than previously thought, and this may have implications for studying the planet formation process in our Solar System."

The objects in the Kuiper Belt are thought to represent the most pristine material our Solar System contains.