Using the Gemini South telescope, part of the International Gemini Observatory funded by the U.S. National Science Foundation and operated by NSF NOIRLab, and the Magellan Baade Telescope at Las Campanas Observatory, astronomers have achieved a groundbreaking milestone: the first near-infrared observation of a recurrent nova outside the Milky Way. This discovery revealed extraordinary chemical emissions and one of the hottest temperatures ever recorded for a nova, indicating an exceptionally violent eruption.
Nova explosions occur in binary star systems where a white dwarf—the dense remnant of a dead star—accumulates material from a companion star until it triggers a thermonuclear explosion. While most novae erupt only once, recurrent novae experience multiple eruptions over time.
The observed nova, LMC 1968-12a (LMC68), is located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. With a recurrence period of about four years, LMC68 is one of the most frequently erupting novae known. Its latest eruption in August 2024 was first detected by the Neil Gehrels Swift Observatory, followed by critical follow-up observations with the Magellan Baade Telescope nine days later and the Gemini South telescope 22 days after the outburst.
The Magellan Baade Telescope played a pivotal role in capturing the nova’s near-infrared spectrum during its ultra-hot phase. The data revealed an unprecedented emission of ionized silicon, shining 95 times brighter than the Sun’s total light output across all wavelengths. This finding, combined with the absence of other expected elemental signatures, suggested an exceptionally high gas temperature of 3 million degrees Celsius (5.4 million degrees Fahrenheit)—one of the hottest ever recorded for a nova.
The extreme conditions are attributed to the low metallicity of the Large Magellanic Cloud, which allows more material to accumulate on the white dwarf before ignition, resulting in a more violent explosion. The Magellan Baade Telescope’s observations provided crucial insights into the nova’s behavior, supporting theoretical predictions about the impact of low-metallicity environments on nova eruptions.
This study marks the first near-infrared spectroscopic observation of an extragalactic recurrent nova, highlighting the importance of advanced telescopes like Gemini South and Magellan Baade in expanding our understanding of these rare cosmic events.
Image Credit: International Gemini Observatory/NOIRLab/NSF/AURA/M. Garlick, M. Zamani