Jwst

WISE 0855 is the coldest brown dwarf anyone has found, at about 265 K (−8 °C), and it sits 2.28 parsecs (about 7.4 light-years) from the Sun. A team led by Brittany Miles of the University of Arizona’s Steward Observatory pointed JWST’s NIRSpec spectrograph at it for 11 hours, taking a spectrum every 15 minutes. As the object rotated, the spectra changed in two separate ways. High in the atmosphere, the team finds patchy water clouds whose thickness varies from one side to the other. Deeper down, carbon monoxide and phosphine rise and fall together, which the team reads as temperature changes in gas welling up from the interior. The paper, “Water Cloud and Chemical Modulations in the Coldest Brown Dwarf”, is on arXiv and listed as accepted to The Astronomical Journal. The University of Arizona announced it on 9 October. ...

The leading explanation for our Moon is a crash: something roughly the size of Mars hit the young Earth, and the debris that stayed in orbit pulled itself together into the Moon. Nobody was around to watch that, but a new study shows we can watch the same kind of event around other stars through the dust it leaves behind. Kate Su of the Space Science Institute in Boulder and nine co-authors combined JWST and Spitzer mid-infrared spectra of 21 “extreme debris disks”, rare systems where planet-sized bodies are colliding right now. The dust chemistry splits them in two. Silica-rich disks point to violent crashes between Mars-sized embryos, and they turn up only around stars younger than about 300 million years. Silica-poor disks point to Moon-sized impacts, and they also appear around much older stars. The paper is accepted in The Astrophysical Journal (preprint: arXiv:2607.06684), and NASA and ESA/Webb released it on 2026-10-01. ...

We have more than 6,000 confirmed exoplanets and not one confirmed moon around any of them. A preprint that went up on 2026-09-04 didn’t change that count. Columbia’s David Kipping pointed JWST at a temperate super-Earth about 100 light-years away, stacked twelve transits, and came up empty. No moon. What makes the paper worth reading is the empty part. It’s the most sensitive exomoon search anyone has run, and a clean non-detection is exactly the result the field needed to prove its main tool still works. ...

Every planet, ours included, assembled inside a flat disk of gas and dust that has since vanished. That disk is the raw material and the deadline at once: it survives only a few million years around a young star before the gas is gone, and any world that wants a thick hydrogen-helium atmosphere has to grab it before the tank runs dry. A new study led by Naman Bajaj at the University of Arizona used JWST to watch that gas actually leaving, mapping the jets and winds carrying it off in 72 young disks and showing how the escape route changes as a disk ages. The paper, “JWST/MIRI Reveals the Evolution from Molecular to Atomic Disk Winds”, is one of the largest JWST disk-wind surveys to date. ...

When you weigh a galaxy, you’re really weighing its light. Point a telescope at an elliptical galaxy a few billion light-years away and you record a smear of photons, and most of that light comes from a small number of bright, heavy stars. The faint red dwarfs, the ones that make up the overwhelming majority of any galaxy’s star count, are individually invisible at that distance. You never see them one by one. You infer how many there are, and you do that by assuming a galaxy far away is built from the same mix of stars as the ones nearby. ...

For almost a decade, the most closely watched rocky planet in the exoplanet catalogue has been LHS 1140 b: a super-Earth in the habitable zone of a quiet red dwarf about 48 light-years away, in the constellation Cetus. The open question was never whether it exists. We’ve known that since 2017. The question was whether a small planet sitting that close to a red dwarf could hold onto an atmosphere at all. A paper published in Science on July 16 gives the strongest answer yet, and it comes from an unexpected direction: the planet is losing gas. A Harvard-led team caught helium streaming off the top of its atmosphere. That leak, counterintuitively, is the best evidence we have that there’s an atmosphere down there to leak from. ...

I’ve now watched three objects from other star systems pass through ours, and only one of them said anything worth hearing. The first, 1I/ʻOumuamua in 2017, was gone almost before we understood what it was: a fast, tumbling sliver that never grew a tail and left us arguing about its shape. The second, 2I/Borisov in 2019, was a proper comet with a coma and a tail, alien in origin, but the kind of object we already know how to study. The third is 3I/ATLAS, and it did what the other two wouldn’t. It stayed in front of the James Webb Space Telescope long enough for Webb to read its chemistry line by line, and the readout points to a comet that froze into existence before the Sun did. ...

Since 2022, the James Webb Space Telescope has been turning up compact red objects in the deep universe that nobody predicted. More than 300 of these “little red dots” have been catalogued so far, all crammed into a narrow epoch between about 600 million and 1.6 billion years after the Big Bang. For four years, they’ve driven a sharp debate: are they impossibly massive galaxies, overgrown black holes, or something we haven’t modelled yet? A paper published on June 10 in The Astrophysical Journal by Vasily Kokorev and colleagues at the University of Texas at Austin delivers the strongest answer so far. The object they studied, GLIMPSE-17775, is a supermassive black hole cocooned in dense, hot gas — and the data suggest most little red dots are, too. ...