INAF Arcetri Journal

The monthly newsletter of the INAF Arcetri Astrophysical Observatory

May-June 2026 | Issue 3

Scientific Spotlight

Rebrightening of a supermassive black hole in ESO 511-G030

For the first time, the entire time evolution of the reactivation of an accretion disk around a supermassive black hole has been obtained. The study shows that the black hole's accretion disk, after about three years of extremely reduced activity, began to regenerate around 2021 and recovered most of its original luminosity by 2023, increasing its luminosity by over an order of magnitude.

The study, published in The Astrophysical Journal, is co-authored by Emanuele Nardini of INAF Arcetri, Elisabeta Lusso and Guido Risaliti of University of Florence.

“Directly Tracking the Rebrightening of a Supermassive Black Hole Accretion Disk", Middei R., Nardini E. et al., The Astrophysical Journal (2026)

Further information:

News on INAF Arcetri website (ITA)

The sky brightness at low radio frequencies

The sky brightness at low radio frequencies, between 60 and 350 megahertz, has been measured with unprecedented precision, indicating that the radio sky is brighter than predicted by some reference radio astronomy models. This result will be crucial for future observations of the early universe with the SKA-Low antenna systems.

The study, published in Nature Astronomy, is co-authored by Pietro Bolli of INAF Arcetri.

“Precise Measurement of the Absolute Sky Brightness at 60 to 350 MHz” , Mckay L. et al., Nature Astronomy (2026)

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Credits: Ravi Subrahmanyan

Observational evidence of magnetic fields on exoplanets

Measurements made by the Very Large Telescope and the Gemini North telescope have provided the first solid observational evidence for the presence of magnetic fields on exoplanets. By analyzing the atmospheric winds of seven gas giant planets, researchers discovered that hotter planets exhibit slower winds, an effect that can only be explained by the presence of magnetic fields.

The study, published in Nature Astronomy, is co-authored by Lorenzo Pino of INAF Arcetri.

“Magnetic field strengths of hot giant exoplanets consistent with Solar System values”, Seidel J.V. et al., Nature Astronomy (2026)

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Credits: Eso/M. Kornmesser, L. Calçada

Mass of supermassive black hole measured in QSO1

Observations from the JWST have made it possible to directly and dynamically measure the mass of the black hole dating back more than 13 billion years in the little red dot QSO1. The data reveal an object that accounts for two-thirds of the entire system's mass, suggesting that, in the early universe, black holes were born already large, preceding the formation of stars and their host galaxies.

The study, published in Nature, is co-authored by Giovanni Cresci of INAF Arcetri and Cosimo Marconcini and Alessandro Marconi of University of Florence.