The heart of the remnants of the supernova SN 1987A studied by ALMA

Remnant of Supernova 1987A seen by ALMA (Image ALMA (ESO/NAOJ/NRAO); R. Indebetouw; NASA/ESA Hubble)
Remnant of Supernova 1987A seen by ALMA (Image ALMA (ESO/NAOJ/NRAO); R. Indebetouw; NASA/ESA Hubble)

Two articles, one published in the journal “Monthly Notices of the Royal Astronomical Society” and one in the “Astrophysical Journal Letters”, describe different aspects of a research on the supernova 1987A (SN 1987A). Several researchers used the ALMA radio telescope discovering for the first time a series of molecules in the supernova remnants. This allowed to create a 3D map of what was called a dust factory and to find clues even about star birth.

SN 1987A was spotted in the Great Magellanic Cloud, one of the dwarf galaxies satellites of the Milky Way, on the night between 23 and 24 February 1987. 30 years later a meeting celebrated that sighting and was useful from a scientific point of view to check the status of the research on this supernova. Meanwhile, other astronomers were continuing to study the remnants using the ALMA radio telescope, inaugurated in March 2013, to take advantage of its power and sensitivity.

The result was the 3D mapping of the molecules that formed within the remnants of SN 1987A – the article on “Astrophysical Journal Letters” is about it – and the discovery of previously unseen molecules – the article on “Monthly Notices of the Royal Astronomical Society” is about it. They’re all clues useful to reconstruct the events seen only partially 30 years ago and to better understand what’s happening right now in that area.

The presence of molecules such as carbon monoxide (CO) and silicon oxide (SiO) was already detected in the past. ALMA also allowed to detect formylium (HCO+) and sulfur monoxide (SO). This is very interesting because it contradicts the idea that the energy developed by a supernova destroyed all existing molecules and dust.

The discovery of those new molecules suggests that a supernova can create very cold clouds of molecules and dust where conditions are similar to those existing in the molecular clouds where star formation takes place. That’s why studies of the consequences of supernovae can also provide information about the formation of new stars and even planets.

These are anti-intuitive connections that can be important when discovered. In supernovae, heavy elements are created that can form new molecules and this “star soot” ajected into interstellar space can end up in other gas and dust clouds and become part of new planets. When one says that we’re stardust as well it’s not just a figure of speech.

This research shows that after 30 years there’s still something to be discovered about SN 1987A, beginning with the possibility that there are still other unidentified molecules within its remnants. Other questions include the abundance of formylium and silicon monoxide and the evolution of the 3D structure of the supernova remnants over time. Last, but certainly not the least, the question of what remained at the center of those remnants. ALMA too will keep on being used for new observations.

Combined observations of SN 1987A (Image NASA/ESA, ALMA (ESO/NAOJ/NRAO))
Combined observations of SN 1987A (Image NASA/ESA, ALMA (ESO/NAOJ/NRAO))

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