Astronomers have observed significantly fewer massive red supergiant stars ending in visible supernovae than theoretical models predict, according to research using the James Webb Space Telescope.
The discrepancy, first noted around 2007, suggests that stars with at least eight times the Sun’s mass may not always explode as supernovae but instead vanish through alternative end-of-life processes.
Two primary hypotheses explain the missing supernovae: direct collapse into black holes without an explosion, or obscuration by dense dust clouds formed during the star’s final stages.
The James Webb Space Telescope’s infrared capabilities allow it to detect both scenarios—either the immediate formation of a black hole or stars hidden behind dust—by observing in wavelengths that penetrate obscuring material.
In 2025, a supernova in the galaxy NGC 1637, approximately 32 million light-years away in the Eridanus constellation, provided a key data point for testing these theories.
The global ASASSN survey detected this event, offering a benchmark for comparing expected versus observed supernova rates among massive stars.
How dust obscuration affects supernova detection rates
If red supergiants are shrouded in self-produced dust, their light would be dimmed and reddened, leading astronomers to underestimate their true brightness and mass.
For more on this story, see James Webb Telescope Reveals Uranus’s Outer Rings Form From Distinct Moon Sources.
This observational bias could cause such stars to be misclassified as less massive, reducing their apparent numbers in surveys and creating the illusion of a deficit in supernova progenitors.
Evidence for this dust-obscuration hypothesis remained elusive until the 2025 supernova in NGC 1637 allowed detailed multi-wavelength analysis.
Webb’s infrared observations are particularly suited to penetrate such dusty environments, potentially revealing the true nature of these obscured massive stars.
Why direct black hole formation remains a viable alternative
The alternative hypothesis posits that some massive stars bypass the supernova phase entirely, collapsing directly into black holes when nuclear fuel is exhausted.
This follows our earlier report, Webb detects water-ice clouds on cold super-Jupiter exoplanet 12 light-years away.
This process would involve core collapse followed by immediate black hole formation without the explosive ejection of material characteristic of supernovae.
Such events would leave little to no transient optical signature, making them nearly invisible to traditional surveys unless detected via gravitational waves or neutrino bursts.
Webb’s sensitivity to infrared emissions from nascent black holes or surrounding material could provide indirect evidence for this scenario.
What does the James Webb Space Telescope contribute to solving this mystery?
The telescope observes in infrared light, enabling it to detect stars obscured by dust or identify signatures of immediate black hole formation that optical telescopes might miss.
How far away was the 2025 supernova used as a reference point?
The supernova in galaxy NGC 1637 occurred approximately 32 million light-years from Earth.
