NASA’s James Webb Space Telescope has made a groundbreaking discovery, providing the best evidence yet for emission from a neutron star at the site of a supernova. The supernova in question, known as SN 1987A, was a core-collapse supernova, which means that the remains at its core formed either a neutron star or a black hole. While indirect evidence for the presence of a neutron star has been found before, this is the first time that the effects of high-energy emission from the probable young neutron star have been detected.
Supernovae are the explosive deaths of massive stars, and they occur within hours, with the brightness of the explosion peaking within a few months. The remains of the exploding star continue to evolve rapidly over the following decades, providing astronomers with a rare opportunity to study this astronomical process in real time.
SN 1987A occurred 160,000 light-years away from Earth in the Large Magellanic Cloud. It was first observed in February 1987 and reached its peak brightness in May of that year. This supernova was particularly significant because it was the first one visible to the naked eye since Kepler’s Supernova in 1604.
Two hours before SN 1987A was first observed, three observatories around the world detected a burst of neutrinos lasting only a few seconds. These observations were linked to the same supernova event and provided crucial evidence for understanding how core-collapse supernovae occur. According to the prevailing theory, this type of supernova should result in the formation of a neutron star or a black hole. Astronomers have been searching for evidence of these compact objects at the center of the expanding remnant material ever since.
While indirect evidence for the presence of a neutron star has been found in recent years, no direct evidence had been observed until now. Claes Fransson of Stockholm University, the lead author of the study, explains that the theoretical models of SN 1987A suggested the formation of a neutron star or black hole based on the 10-second burst of neutrinos observed just before the supernova. However, no compelling signature of a newborn object had been observed until the James Webb Space Telescope made its discovery.
The observations were made by the James Webb Space Telescope’s Medium Resolution Spectrograph (MRS) mode, which is part of the Mid-Infrared Instrument (MIRI). The MRS is an Integral Field Unit (IFU) that allows for imaging and spectroscopic analysis of an object simultaneously. By analyzing the Doppler shift of each spectrum, the team was able to evaluate the velocity at each position.
The spectral analysis revealed a strong signal from ionized argon at the center of the ejected material surrounding SN 1987A. Subsequent observations using Webb’s Near-Infrared Spectrograph (NIRSpec) found even more heavily ionized chemical elements, particularly five times ionized argon. The formation of such ions requires highly energetic photons, indicating the presence of a source of high-energy radiation in the center of the SN 1987A remnant. Based on their findings, the research team concluded that a newly born neutron star is the most likely explanation.
Further observations are planned for this year, both with the James Webb Space Telescope and ground-based telescopes. The team hopes that these ongoing studies will provide more clarity about what is happening at the heart of the SN 1987A remnant. Ultimately, these observations will contribute to the development of more detailed models, allowing astronomers to better understand not only SN 1987A but also all core-collapse supernovae.
The findings of this study were published in the journal Science. The James Webb Space Telescope, an international program led by NASA in partnership with ESA and the Canadian Space Agency, is revolutionizing space science by unraveling mysteries in our solar system, exploring distant worlds around other stars, and investigating the origins of our universe. With its groundbreaking discoveries, Webb is pushing the boundaries of our knowledge and deepening our understanding of the cosmos.