This Week in Astronomy: Euclid's First Great Catalogue, a Pulsing White Dwarf and a Surprise Inside Bennu
A busy week, and an unusually consequential one. Europe's dark Universe mission opened its first big data release to the world, a radio telescope in the Western Australian desert turned up a stellar odd couple nobody expected, a grain of asteroid surprised the chemists studying it, and a probe inside the Sun's atmosphere found order hiding in chaos. Here is what mattered, and why.
Euclid opens its first great catalogue
On 12 November, ESA published DR1-Foundation, the first major data release from the Euclid space telescope, and it is a genuinely enormous thing to hand to the community. The release covers roughly 1,900 square degrees of sky, an area equivalent to about 9,500 full Moons, gathered over some thirteen months of observing between spring 2024 and spring 2025. That is only about 14% of what Euclid will eventually survey across its six-year mission, which tells you something about the scale of what is still to come.
The numbers inside are the real story. The release records light from more than a billion objects, including over 900 million galaxies, more than 60 million quasar candidates, and spectra for over 160 million sources. It also contains around 15,000 strong gravitational lensing candidates, which is the largest such catalogue ever assembled. The whole thing runs to roughly 1.7 million gigabytes.
Why does this matter beyond the sheer heft of it? Euclid's purpose is to measure how cosmic structure has grown over time, and that requires shapes and distances for a vast number of galaxies, measured consistently. Strong lenses are part of that toolkit: each one is a natural telescope that weighs the mass sitting between us and a background galaxy, including the dark matter we cannot see directly. Fifteen thousand candidates is a step change from the few hundred well studied systems astronomers have worked with for years. Crucially, this is a foundation rather than a finished result. Euclid has not announced a new value for dark energy here. It has handed everyone else the raw material to go looking.
The release came with some lovely imagery, including Euclid's view of Abell 3128, a cluster of hundreds of galaxies about 800 million light years away in the Horologium supercluster. In the same frame sits a second cluster roughly 5 billion light years further out, and near the centre a strong lens smears a background galaxy into delicate blue arcs. The exposure took about 70 minutes and covers 0.12 square degrees. Rich southern clusters like this one are well within reach of our own users imaging from Chile, though pulling out lensing arcs is another matter entirely.
Reference: ESA, "Euclid lays the foundation for its best-ever 3D map of the Universe", 12 November 2026
A white dwarf that pulses every eight minutes, with a Sun-like partner
Since 2021, astronomers have been collecting a strange new class of object called long-period transients: sources that emit bright radio pulses on timescales of minutes to hours, far slower than any ordinary pulsar should manage. About a dozen are now known, and the awkward question has always been which star in the system is actually doing the pulsing.
Writing in Nature Astronomy on 12 November, a team led by Dr Sam McSweeney, now a commissioning scientist with the Square Kilometre Array Observatory and previously at the Curtin University node of ICRAR, reported a system that finally answers it. GPM J071507-114153 lies more than 5,000 light years away and pulses every eight minutes. It was picked up by the Murchison Widefield Array, localised by MeerKAT in South Africa, and then pinned down optically by the W. M. Keck Observatory, which revealed the companion to be a G-type star much like our own Sun. Processing the 100 hours and more of radio data fell to the Pawsey Supercomputing Research Centre.
The eight-minute signal tracks the spin of a white dwarf, and because the pulses are sharp enough to follow that star's motion around its orbit, the team could show the emission originates at or very near it rather than the companion. Every previously known system of this kind paired a white dwarf with a small, cool red dwarf. A Sun-like partner is new, and it makes the system a useful bridge between long-period transients and the better understood white dwarf pulsars. There was a bonus, too: the pulses picked up stellar flares on the companion, and what looks like a prominence. As co-author Associate Professor Natasha Hurley-Walker put it, "It's amazing that by using radio wavelengths we can detect the storms on a star over 5000 light-years away."
One molecule from Bennu, two very different histories
The OSIRIS-REx sample of asteroid Bennu, back on Earth since 2023, keeps producing results that complicate the tidy story. In a paper published in Communications Earth & Environment, and announced by Penn State on 10 November, a team led by Ophélie Mcintosh, with principal investigator Katherine Freeman, looked at a single amino acid, beta-alanine, in both the Bennu sample and the venerable Murchison meteorite.
Measured in bulk, the carbon isotopes in the two samples look essentially identical, roughly what you would expect from two primitive, carbon-rich bodies. The team then went further, using instruments that measure isotope ratios at specific atomic positions within a single molecule rather than averaging across it. At that resolution the agreement collapses. The carbon sitting in Bennu's carboxyl position is dramatically enriched in carbon-13, described by the team as the largest isotope anomaly yet recorded in an organic molecule of extraterrestrial origin. "I was genuinely gobsmacked by the enormous isotope difference between two neighboring atom positions," Freeman said.
The measurement itself is the solid part. The interpretation, that the organic material in these two bodies formed in genuinely different environments within the young solar system's disc, is an inference, though a well motivated one: the authors argue the differences are hard to produce by later processing inside the parent asteroids. It is worth being careful with the broader framing that has followed. A single molecule from two objects is a thin basis for conclusions about how widespread prebiotic chemistry is. What it does establish is that bulk measurements have been hiding structure, and that position-specific isotope analysis is a sharp new tool for tracing where organic molecules were built.
Parker Solar Probe finds a twist in the solar wind
Turbulence is meant to be the definition of disorder, so finding reliable structure within it is always interesting. Using Parker Solar Probe data, a team led by Masatomi Iizawa of Technische Universität Braunschweig, working with colleagues at the University of Tokyo and partners across ten countries, reported in The Astrophysical Journal Letters that the solar wind's tangled magnetic fields have a preferred handedness, and that it flips.
Looked at along the outward direction from the Sun, the magnetic field at large scales tends to twist one way; at much smaller scales, the preferred twist reverses. The switch happens at the boundary where the plasma stops behaving like a fluid and starts behaving like a collection of individual particles, which is precisely the region where energy is thought to be dumped into heating the solar wind. The team also found that the reversal grows stronger, and moves to longer wavelengths, the further the wind travels from the Sun. "We see a clear structure in the spectrum, even though the turbulence represents unstructured motions," Iizawa said.
The results are presented qualitatively rather than as hard numbers, and the practical payoff is still some way off. But understanding how energy moves across that fluid to particle boundary sits close to two long-standing puzzles: why the corona is so absurdly hot, and how to forecast the geomagnetic storms that reach us.
Clear skies, and we will see you next week.