The explosion of a massive star is not just a flash: it's a blow to the surrounding gas. But until now, no one had looked at how the gas itself moves at the sites of such explosions. Now astronomers have gathered data on 33 nearby supernovae and for the first time measured the turbulence of the cold molecular gas around them.
It turns out that supernovae occur more often where gas moves faster and more chaotically than the galactic average. It's as if explosions prefer not quiet streets but busy intersections. This picture supports two ideas: either massive stars are born in dense clumps where gas is squeezed and accelerated, or they have companions that stir up the surrounding matter.
A supernova explosion is the final stage in the life of a star heavier than eight Suns. Now it's clearer under what conditions such stars come into being.
as written by the authors arXiv:2608.08380v1
Context. Study of cold molecular hydrogen gas (hereafter molecular gas) provides crucial insights into its interplay with star-forming regions. However, the connection between molecular gas turbulence and the sites of massive star ($$> 8~\rm{M}_{\odot}$$) explosions as core-collapse supernovae (CCSNe) remains unexplored. Aims. We measure for the first time the turbulence of molecular gas in environments of CCSNe, with the aim to constrain the nature of their progenitors. Methods. In order to reach spatial resolutions of giant molecular cloud (GMC) sizes ($$\sim 100~\rm{pc}$$), we collected ALMA carbon monoxide $$J = 2 \rightarrow 1$$ spectral line ($$\sim 230.54~\rm{GHz}$$) observations (as a tracer of molecular gas) at the locations of 33 nearby CCSNe ($$< 100~\rm{Mpc}$$). Results. We found that CCSNe prefer molecular gas regions with high velocity dispersion compared to the average of their host galaxies. Conclusions. For CCSN progenitors, this observational evidence supports their increased formation in regions of high densities and/or their binary nature.
Molecular gas is so cold that its temperature is only about 10–20 degrees above absolute zero, yet inside it stars with temperatures of millions of degrees can be born.
In the series 'Star Trek', supernovae are sometimes used as natural weapons or energy sources, but in reality they only show where giant stars were born and how the gas moved.