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Astronomers Observe Formation of Black Hole from Vanishing Star

A remarkable astronomical event has been documented, as scientists detected the disappearance of a massive star, which has since transformed into a black hole. The supergiant star, designated M31-2014-DS1, boasts a mass approximately twenty times that of our sun and is situated 2.5 million light-years away in the Andromeda galaxy.

The star exhibited an increase in brightness in 2014, but commenced a fading process that began in 2016 and persisted until 2023, at which point it became impossible to observe with existing telescopes. This unusual behavior diverges from typical stellar phenomena, where massive stars usually culminate in explosive supernova events at the end of their life cycles.

In this specific instance, however, no stellar explosion has been recorded, leading researchers to propose that M31-2014-DS1 may represent a rare instance of a “failed supernova.” Their findings were shared on October 18 through the preprint website arXiv, with further validation pending peer review.

The study’s authors emphasized the significance of M31-2014-DS1’s prolonged dimming, stating, “The dramatic and sustained fading of M31-2014-DS1 is exceptional in the landscape of variability in massive, evolved stars.” They further elaborated that the absence of a brilliant outburst reinforces the idea that the star underwent a collapse leading to the core’s transformation without the typical supernova signature.

Stars primarily produce energy through nuclear fusion, converting hydrogen into helium. As hydrogen depletes, these massive stars begin fusing heavier elements until their cores become saturated with iron, causing the stellar outward pressure to weaken and ultimately resulting in the star’s rapid implosion.

Usually, stars with masses exceeding eight solar masses experience a rebound effect that triggers a supernova, resulting in either a black hole or a neutron star. However, this transition is not universal, as recent observations have indicated that some massive stars might directly collapse into black holes without the dramatic ejection of material typically associated with supernovae—events referred to as failed supernovae.

Detecting such elusive phenomena is challenging, which explains why documented instances remain scarce. To investigate potential cases of failed supernovae, the researchers utilized data from the Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE). This space telescope combed through the cosmos searching for galaxies and black holes until it was decommissioned on November 1, 2024.

After closely monitoring M31-2014-DS1, astronomers observed a significant dimming from 2016 to 2019, and subsequent follow-ups revealed that the star had entirely vanished by 2023. The absence of any supernova observations during this time led the researchers to conclude that about 98% of the star’s mass had collapsed, resulting in the formation of a black hole with an estimated mass of 6.5 solar masses.

This event was compared to another candidate for a failed supernova, N6946-BH1, located 22 million light-years away in the galaxy known as NGC 6946, or the “Fireworks Galaxy.” The researchers indicate that future observations are essential to detect potential X-ray emissions from these candidates, which would provide further evidence of their origins linked to failed supernovae.

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