Comet 220P/McNaught, belonging to the Jupiter family, orbits the Sun every 5.5 years. Although its closest approach to Earth was in October, its unexpected brightness has captured scientific attention due to two outbursts. The study presents calibrated photometric observations after the first outburst (May 31) and combines them with public data from the ATLAS system to constrain the comet's nature and properties. Dust expansion velocity, ejected mass, and kinetic energy have been determined, among other parameters.
Josep M. Trigo-Rodríguez, lead author and researcher at ICE-CSIC and the Institut d’Estudis Espacials de Catalunya (IEEC), notes that Jupiter-family comets are interesting due to their migration towards the inner solar system and their Earth-crossing orbits, posing a potential impact risk.
Comets can increase their brightness magnitude millions of times by releasing dust, organic matter, and ices that disintegrate around the nucleus, enhancing the coma's ability to scatter sunlight. The international team, including Marcin Wesolowski, Maria Gritsevich, and Peter Carson, conducted observations from the Montseny Astronomical Observatory (Catalonia) and the Fregenal de la Sierra Observatory (Extremadura).
Trigo-Rodríguez explains that the comet shed parts of its 'crust,' creating a dust-rich envelope that increased its brightness 250-fold in half a day (first outburst, May 31). The second outburst (August 5) made it about 16,000 times brighter, observable with amateur telescopes. These results suggest that rapid sublimation of volatile ices exposed to sunlight can break the 'crust,' releasing dusty aggregates.
Analyzing the long-distance behavior of comets provides insights into their size and nature. The team continues to study comet 220P, searching for signs of core fragmentation. The strength of these bodies is crucial for quantifying impact risk, as many comets are extremely fragile and disintegrate.
The reference article is "Photometry and analysis of comet 220P/McNaught during the 2026 outbursts," published in Monthly Notices of the Royal Astronomical Society. The communication is from ICE-CSIC.
