Astronomers may have caught a young planet in the process of forming, sculpting its surroundings within a disc of gas and dust encircling its host star. Using the European Southern Observatory’s (ESO) Very Large Telescope (VLT), researchers observed striking spiral arms in a protoplanetary disc — and for the first time, found evidence of a planet candidate nestled within such a spiral.

“We will never witness the formation of Earth, but here, around a young star 440 light-years away, we may be watching a planet come into existence in real time,”
— Francesco Maio, doctoral researcher at the University of Florence, Italy, and lead author of the study published in Astronomy & Astrophysics.

The forming planet was detected within the disc surrounding the star HD 135344B. Estimated to be about twice the mass of Jupiter and orbiting its star at a distance comparable to Neptune’s distance from the Sun, this young planet appears to be actively shaping its environment as it grows.

Protoplanetary discs, composed of gas and dust, often display features like rings, gaps, or spirals. These structures have long been theorized to result from the gravitational influence of nascent planets. However, direct observation of such a planet embedded within the spirals has eluded astronomers — until now.

Earlier observations of HD 135344B using the SPHERE instrument on ESO’s VLT revealed the disc’s striking spiral arms, but no planet had been definitively identified within the structure. The breakthrough came with the use of a newer instrument: the Enhanced Resolution Imager and Spectrograph (ERIS). It allowed researchers to detect a planet candidate located precisely at the base of one of the spiral arms — exactly where models predicted a planet might reside.

“What makes this detection potentially a turning point is that, unlike many previous observations, we are able to directly detect the signal of the protoplanet, which is still highly embedded in the disc,”
— Maio, who is also based at the Arcetri Astrophysical Observatory, part of Italy’s National Institute for Astrophysics (INAF).
“This gives us a much higher level of confidence in the planet’s existence, as we’re observing the planet’s own light.”

A Companion Emerges Around a Different Young Star

In a parallel study, another team of astronomers also used the ERIS instrument to investigate the young star V960 Mon, still in the early stages of its life. Their findings, published on July 18 in The Astrophysical Journal Letters, reveal a mysterious companion object near the star — though its exact nature remains uncertain.

Led by Anuroop Dasgupta, a doctoral researcher at ESO and Diego Portales University in Chile, the team built on earlier observations made with SPHERE and the Atacama Large Millimeter/submillimeter Array (ALMA). These earlier studies showed that V960 Mon’s surrounding disc displayed complex spiral arms and was undergoing a process called gravitational instability, where dense clumps of material can collapse to form planets or even larger objects.

“That work revealed unstable material but left open the question of what happens next. With ERIS, we set out to find any compact, luminous fragments signalling the presence of a companion in the disc — and we did,”
— Dasgupta.

The object, found near one of the known spiral arms, could either be a young planet forming from the disc or a brown dwarf — a substellar object more massive than a planet but too small to ignite as a star. If confirmed, this would be the first clear detection of a planetary-mass companion forming by gravitational instability.

About the Research and Institutions Involved

The HD 135344B study is documented in the paper “Unveiling a protoplanet candidate embedded in the HD 135344B disk with VLT/ERIS”, to appear in Astronomy & Astrophysics. The research was conducted by an international team from institutions including the University of Florence, INAF-Osservatorio Astrofisico di Arcetri, University of Bologna, and the Max Planck Institute for Astronomy, among others.

The V960 Mon study, “VLT/ERIS observations of the V960 Mon system: a dust-embedded substellar object formed by gravitational instability?”, is published in The Astrophysical Journal Letters. The team behind this work is part of the Millennium Nucleus on Young Exoplanets and their Moons (YEMS), based in Chile, with contributors from ESO, Diego Portales University, the University of Santiago, CIRAS, and institutions in Italy and India.

About ESO and ALMA

ESO enables groundbreaking astronomical discoveries by designing, building, and operating some of the world’s most advanced ground-based observatories. It is supported by 16 member states and operates telescopes in the Atacama Desert, including the Very Large Telescope (VLT), ALMA (in partnership with international collaborators), and the future Extremely Large Telescope (ELT).

The Atacama Large Millimeter/submillimeter Array (ALMA) is an international collaboration between ESO, the U.S. National Science Foundation (NSF), and Japan’s National Institutes of Natural Sciences (NINS), in cooperation with the Republic of Chile and additional partners from Taiwan, Korea, and Canada.

Original Publication
Authors: F. Maio, D. Fedele, V. Roccatagliata, S. Facchini, G. Lodato, S. Desidera, A. Garufi, D. Mesa, A. Ruzza, C. Toci, L. Testi, A. Zurlo and G. Rosotti.
Journal: Astronomy and Astrophysics
DOI: 10.1051/0004-6361/202554472

Original Source: https://www.eso.org/public/news/eso2513/