Free Astronomy Magazine September-October 2025

21 SEPTEMBER-OCTOBER 2025 ASTRO PUBLISHING Protoplanetary discs have been observed around ot- her young stars, and they often display intricate pat- terns, such as rings, gaps or spirals. Astronomers have long predicted that these structures are caused by baby planets, which sweep up material as they orbit around their parent star. But, until now, they had not caught one of these plane- tary sculptors in the act. In the case of HD 135344B’s disc, swirling spiral arms had previously been detected by another team of astron- omers using SPHERE (Spec- tro-Polarimetric High-con- trast Exoplanet REsearch), an instrument on ESO’s VLT. However, none of the previ- ous observations of this sys- tem found proof of a planet strument to observe an- other star, V960 Mon, one that is still in the very early stages of its life. In a study published on 18 July in The Astrophysical Jour- nal Letters , the team re- port that they have found a companion object to this young star. The exact na- ture of this object remains a mystery. The new study, led by Anuroop Dasgupta, a doc- toral researcher at ESO and at the Diego Portales University in Chile, follows up observations of V960 Mon made a couple of years ago. Those observa- tions, made with both SPHERE and the Atacama Large Millimeter/submil- limeter Array (ALMA), re- vealed that the material orbiting V960 Mon is shaped into a series of intricate spiral arms. They also showed that the material is fragmenting, in a process known as ‘gravitational instability’, when large clumps of the material around a star contract and collapse, each with the potential to form a planet or a larger object. “That work revealed unstable material but left open the question of what happens next. With ERIS, we set out to find any compact, lumi- nous fragments signalling the pres- ence of a companion in the disc — and we did,” says Dasgupta. The team found a potential companion object very near to one of the spiral arms observed with SPHERE and ALMA. The team say that this object could either be a planet in formation, or a ‘brown dwarf’ — an object big- ger than a planet that didn’t gain enough mass to shine as a star. If confirmed, this companion object may be the first clear detection of a planet or brown dwarf forming by gravitational instability. T his video zooms into HD 135344B, a young star located around 440 light-years away. The star is surrounded by a disc of dust and gas with prominent spiral features. New observations obtained with ESO’s Very Large Telescope (VLT) may have unveiled a planet that could be sculping these features. The video combines images taken with dif- ferent telescopes at different times and various wave- lengths. [ESO/L. Calçada/N. Risinger (skysurvey.org )/VMC Survey/Digitized Sky Survey 2/ALMA (ESO/NAOJ/NRAO)/N. van der Marel et al./T. Stolker et al./F. Maio et al.] T his image, taken with ESO’s Very Large Telescope (VLT), shows a possible companion orbiting the young star V960 Mon. The image was captured with the VLT’s Enhanced Resolution Imager and Spectrograph (ERIS) instrument. The properties of the object are unknown: it could be a planet or a brown dwarf –– an object bigger than a planet that didn’t gain enough mass to shine as a star. [ESO/A. Dasgupta] forming within the disc. Now, with observations from the new VLT’s En- hanced Resolution Imager and Spec- trograph (ERIS) instrument, the re- searchers say they may have found their prime suspect. The team spotted the planet candi- date right at the base of one of the disc’s spiral arms, exactly where the- ory had predicted they might find the planet responsible for carving such a pattern. “What makes this detection poten- tially 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,” says Maio, who is based at the Arcetri Astro- physical Observatory, a centre of Italy’s National Institute for Astro- physics (INAF). “This gives us a much higher level of confidence in the planet’s existence, as we’re observ- ing the planet’s own light.” A different team of astronomers have also recently used the ERIS in- !