New ALMA observations reveal one of the largest debris rings ever detected, offering fresh clues to the architecture of young planetary systems.

A team of astronomers led by YEMS researcher James Miley (Física USACH, ALMA Observatory) has used the Atacama Large Millimeter/submillimeter Array (ALMA) to obtain the first resolved image of the debris disc around the A-type star HD 126062, uncovering a remarkably large and nearly face-on exo–Kuiper belt more than 500 astronomical units across. The study, published in Astronomy & Astrophysics, also reveals extended carbon-monoxide gas near the system — gas which, intriguingly, may not belong to the star at all.

HD 126062 lies ~134 light-years away in the Lower Centaurus Crux / Upper Centaurus Lupus region, a nearby young stellar association about 15–20 Myr old — an age at which most protoplanetary discs have already dissipated. Despite this, ALMA now shows that the star still hosts a substantial reservoir of cold dust.

A belt among the largest ever seen

The ALMA continuum data reveal a broad, cold ring of millimetre-sized grains centered at ~270 au from the star — roughly ten times the size of our Solar System’s Kuiper belt. The ring is relatively narrow and almost perfectly face-on, allowing astronomers to model its structure with high precision.

Image of the debris disk discovered around HD126062 by Miley et al.
Image of the debris disk discovered around HD126062 by Miley et al. using ALMA observatory.

The new detection confirms earlier infrared hints of a wide reservoir of cold dust. The team also finds a second, warmer dust component around ~20 au, indicating a two-belt architecture similar to those seen around other young A-type stars.

A mystery in molecular gas

ALMA observations of the CO (2–1) line, which traces molecular gas, show emission that is velocity-offset and spatially extended well beyond the dust belt. The properties do not match standard debris-disc gas scenarios, pointing instead to a diffuse interstellar cloud along the line of sight rather than gas originating within the disc itself.

Belt–planet parallels

Among known debris-disc systems, the exo–Kuiper belt of HR 8799 is the closest analogue to that found in HD 126062. In HR 8799, a wide outer belt coexists with four directly imaged giant planets. Could massive, distant planetesimal belts be closely connected to the presence of wide-orbit planets? Confirming such a link will require deeper, high-resolution observations of HD 126062 to search for planets shaping its newly resolved disc.

What’s next

The team is already planning follow-up: new ALMA imaging could reveal subtle substructures in the ring, measure its eccentricity, or detect asymmetries hinting at planetary influence. High-contrast imaging with VLT/SPHERE, JWST/MIRI, or future ELT instruments could further narrow the search for planets interior to the disc.