Before dying in a supernova explosion, massive stars are enveloped in a cloud of matter that dramatically reduces their apparent brightness. This process develops over a period of only a few months, allowing us to predict the onset of cosmic catastrophe.
Some stars end their lives by exploding as supernovae. A sudden and bright flash is accompanied by the shedding of outer shells, leaving behind - depending on the initial size - a black hole or a neutron star. Such an ending is typical of massive stars, red supergiants like the famous Betelgeuse, which gain eight or more solar masses.
As soon as they exhaust their internal resources to continue thermonuclear fusion, the core rapidly collapses and "bounces" back, exploding the star. From the outside, this process develops unexpectedly, and it is not yet possible to predict in advance the moment of a supernova explosion. From the same Betelgeuse it is expected almost at any moment, which by astronomical standards may mean tomorrow, and in a couple of million years.
A new article by astronomers from France and Britain, published in the journal Monthly Notices of the Royal Astronomical Society, is devoted to this problem. Ben Davies (Ben Davies) and his co-authors focused on type II-P supernovae. Before the outburst, such stars abruptly dump the matter that surrounds them in a cloud. During the explosion, it gets very hot and then gradually cools down, so that Type II-P supernovae are characterized by a fairly slow decay.
Scientists have modeled several alternative mechanisms for the accumulation of circumstellar matter. The simulation results were compared with archival images of distant giants, which subsequently exploded supernovae II-P. The work showed that the formation of the cloud is rapid. The process takes less than a year - sometimes several months - and leads to a drop in the apparent brightness of the star by tens or even hundreds of times.
This allows us to hope that now we will be able to predict the outbursts of some supernovae in advance. If a red supergiant is rapidly enveloped in a cloud of matter and fades, an explosion can be expected at any time - tomorrow or in a few months.
