Weekly astronomy recap: the most distant fast radio burst, two planetary families and genuinely green stars
A week of long distances and careful measurements. Astronomers pushed the fast radio burst frontier back to an era when the Universe was three billion years old, sorted the known planetary systems into two families, worked out what white dwarfs would really look like to the eye, and resurrected a ghostly radio relic hidden behind our own galaxy. Here are the four results we think matter most.
A fast radio burst from when the Universe was three billion years old
Fast radio bursts are among the strangest signals in astronomy. Each lasts around a thousandth of a second, yet releases more energy than the Sun manages in several days. We have caught thousands, but only around a hundred have been traced to a specific host galaxy, and almost all of those sit relatively close by in cosmic terms.
FRB 20240304B has broken that pattern decisively. Reported in Science by Manisha Caleb of the University of Sydney and 27 colleagues, the burst comes from a galaxy at redshift 2.148, placing it roughly three billion years after the Big Bang. That roughly doubles the redshift reach of localised bursts in a single step.
MeerKAT in South Africa caught the burst on 4 March 2024, working through the MeerTRAP project. Pinning down where it came from was the harder half of the job: the host galaxy was invisible to the largest ground-based telescopes, and it took the James Webb Space Telescope's NIRCam to find it. What Webb revealed is surprising. The host is a clumpy dwarf galaxy around a thousand times less massive than the team expected, poor in heavy elements, and forming stars so furiously that most of its stellar content may have assembled within the previous thirty million years.
Two things make this more than a record. First, fast radio bursts are superb probes of the thin ionised gas strung between galaxies, the ordinary matter that is notoriously hard to see by any other means. This single sightline samples something like 80 per cent of cosmic history, and it passes through the Virgo Cluster and a foreground group on the way, which lets the team trace magnetic structure across gigaparsecs. Second, a small, metal-poor, vigorously star-forming host fits the picture in which at least some bursts come from young magnetars, the ultra-magnetised neutron stars left behind when massive stars explode. Caleb considers a neutron star merger very unlikely here. Ben Stappers, who leads MeerTRAP, puts the next question simply: how much closer can this frontier be pushed towards the first generations of stars?
Reference: Sydney astronomers pinpoint the most distant fast radio burst ever detected, University of Sydney, 13 October 2026.
Planetary systems come in two families, and the star decides which
We now know of more than a thousand systems with multiple confirmed planets, which until recently was a catalogue rather than a classification. A new Nature Astronomy study, led jointly by Diego Turrini of INAF and Camilla Danielski of the University of Valencia, argues that the catalogue divides cleanly in two.
The team took the 300 best characterised multi-planet systems and measured both their total planetary mass and their dynamical temperature, using a quantity called the normalised angular momentum deficit. A high value means eccentric, mutually inclined orbits, the fingerprint of a violent past. What emerged was a genuine bimodality rather than a smooth spread.
One family is compact and modest. Its planets share similar masses and sizes, the familiar peas-in-a-pod arrangement, usually packed inside orbits tighter than Mercury's, and they are dynamically calm in much the same way the Solar System is. These systems sit around stars with masses and metallicities at or below the Sun's.
The other family is heavier and rougher. Total planetary mass runs from two to ten times the Solar System's, the host stars are more massive and richer in metals, and the orbits are around an order of magnitude more dynamically excited. Modelling suggests these systems form in discs roughly three times richer in gas and solids, and that they were unstable almost from birth, with planet scattering doing the rest.
The authors are careful about the caveat. Danielski notes that selection effects were the team's main worry throughout, since current surveys struggle to find anything resembling our own arrangement. The structural differences survive that scrutiny, but the gap may yet narrow as detections improve.
Reference: Two families of multi-planet systems with distinct architectures and stellar hosts, Nature Astronomy, 13 October 2026.
White dwarfs really are white, except when they are green
Here is a question nobody had properly answered: if you could float beside a white dwarf, what colour would it look? Mark Hollands and colleagues at the University of Warwick took spectra of 151 white dwarfs within 20 parsecs, about 65 light years, and pushed them through a model of human colour vision.
Reassuringly, the name holds up. The median object matches a blackbody of roughly 6,800 K, which the eye reads as white. Hotter, bluer white dwarfs are brighter and therefore over-represented in magnitude-limited surveys, which is why the popular impression skews blue.
The interesting part is the roughly one in thirty that refuse to behave. WD J1330+6435, at around 4,000 degrees Celsius, has swallowed rocky debris, leaving its atmosphere seasoned with calcium, lithium and sodium. The sodium absorbs the orange part of the spectrum, and the result is chartreuse green: arguably the first genuinely green star identified in the Galaxy. WD J1011+2845, just 48 light years away, goes the other way, with carbon molecules shunting nearly all its light beyond 600 nanometres for a salmon pink glow that may make it the reddest star on record.
The physics underneath is extreme. These atmospheres approach one gram per cubic centimetre, the density of water and millions of times denser than the Sun's photosphere. It is also a useful reminder for anyone processing their own colour data, whether from a Telescope Live instrument or a back garden setup: what a sensor records and what an eye would perceive are two different questions, and the second takes real work to answer.
Reference: Green, pink and purple: astronomers reveal the surprising true colours of white dwarf stars, University of Warwick, 15 October 2026.
A radio phoenix rises behind the Milky Way
Roughly a fifth of the sky is effectively closed to extragalactic astronomy. Dust and stars in the plane of our own Galaxy block the view, which is why the region carries the gloomy name Zone of Avoidance. Objects hiding there tend to go misidentified for decades.
VLSSJ0318.9+5755, nicknamed the Treble Clef for its curling filaments, is a good example. It was first taken for a pulsar. In a new Astronomy and Astrophysics paper, Andrea Botteon of INAF and collaborators combine fresh uGMRT observations with LOFAR survey data, plus X-rays from Chandra and SRG, and show it to be something more interesting: a radio phoenix in a massive, merging galaxy cluster that nobody had properly characterised before.
The story they reconstruct runs like this. The cluster's brightest galaxy hosted a supermassive black hole outburst, filling the surroundings with relativistic plasma. That plasma aged and faded into radio silence. Several hundred million years later a cluster merger swept through, compressed the fossil plasma and lit it up again. The spectrum is extraordinarily steep, falling off faster than the fourth power of frequency between 400 and 650 MHz, which is just what re-energised old electrons should look like. Turbulent gas motions from the merger appear to shape the filaments, and may also power a tentative radio halo at the cluster centre.
It is a neat demonstration that the Zone of Avoidance is becoming rather less avoidable, and the authors flag the Treble Clef as a prime early target for LOFAR2.0.
Reference: The Treble Clef radio phoenix and its old nonthermal filaments, Astronomy and Astrophysics, 9 October 2026.
Clear skies, and we will see you next week.