In 2019, indirect evidence for the presence of a collapsed neutron star within the remnants of SN 1987A was discovered using the Atacama Large Millimeter Array telescope.

SN 1987A was discovered independently by Ian Shelton and Oscar Duhalde at the Las Campanas Observatory in Chile on February 24, 1987, and within the same 24 hours by Albert Jones in New Zealand.

[8] Some models of SN 1987A's progenitor attributed the blue color largely to its chemical composition rather than its evolutionary stage, particularly the low levels of heavy elements.

[10] However, it is now widely understood that blue supergiants are natural progenitors of some supernovae, although there is still speculation that the evolution of such stars could require mass loss involving a binary companion.

This was likely due to neutrino emission which occurs simultaneously with core collapse, but before visible light is emitted as the shock wave reaches the stellar surface.

Approximately three hours earlier, the Mont Blanc liquid scintillator detected a five-neutrino burst, but this is generally not believed to be associated with SN 1987A.

[21][22] In 2019, evidence was presented for a neutron star inside one of the brightest dust clumps, close to the expected position of the supernova remnant.

[27] In 2024, researchers using the James Webb Space Telescope (JWST) identified distinctive emission lines of ionized argon within the central region of the Supernova 1987A remnants.

[28] Much of the light curve, or graph of luminosity as a function of time, after the explosion of a type II supernova such as SN 1987A is produced by the energy from radioactive decay.

Later measurements by space gamma-ray telescopes of the small fraction of the 56Co and 57Co gamma rays that escaped the SN1987A remnant without absorption[34][35] confirmed earlier predictions that those two radioactive nuclei were the power source.

This was noticed by the Hubble Space Telescope as a steady increase in luminosity 10,000 days after the event in the blue and red spectral bands.

[39] The three bright rings around SN 1987A that were visible after a few months in images by the Hubble Space Telescope are material from the stellar wind of the progenitor.

A part of the x-ray radiation, which is absorbed by the dense ejecta close to the center, is responsible for a comparable increase in the optical flux from the supernova remnant in 2001–2009.

These findings are also supported by the results of a three-dimensional hydrodynamic model which describes the interaction of the blast wave with the circumstellar nebula.

The possibility that the IR excess could be produced by optically thick free-free emission seemed unlikely because the luminosity in UV photons needed to keep the envelope ionized was much larger than what was available, but it was not ruled out in view of the eventuality of electron scattering, which had not been considered.

[citation needed] However, none of these three groups had sufficiently convincing proofs to claim for a dusty ejecta on the basis of an IR excess alone.

[52] This seemingly straightforward interpretation of the nature of the IR emission was challenged by the ESO group[53] and definitively ruled out after presenting optical evidence for the presence of dust in the SN ejecta.

However, a much larger reservoir of ~0.25 solar mass of colder dust (at ~26 K) in the ejecta of SN 1987A was found[59] with the infrared Herschel Space Telescope in 2011 and confirmed with the Atacama Large Millimeter Array (ALMA) in 2014.

The data show that CO and SiO distributions are clumpy, and that different nucleosynthesis products (C, O and Si) are located in different places of the ejecta, indicating the footprints of the stellar interior at the time of the explosion.