In a surprising discovery, astronomers using the Hubble Space Telescope have discovered that a powerful stream of energy from a supermassive black hole appears to be causing stars in a nearby galaxy to explode.

This jet, which shoots out of the black hole like a blowtorch at close to the speed of light, appears to trigger faster eruptions of stars, called novae, along its path.

The research by Alec Lessing of Stanford University and his team was published on the arXiv preprint server.

The findings perplexed scientists because they challenge our current understanding of how black hole jets interact with the space around them.

A nova is a type of stellar explosion that occurs in a binary system. In such systems, a large, aging star transfers hydrogen to a smaller, dense star called a white dwarf.

When a white dwarf accumulates enough hydrogen on its surface, the gas ignites in a powerful explosion, similar to a giant atomic bomb.

Interestingly, this explosion does not destroy the white dwarf; it simply sheds its outer layer and then starts accumulating hydrogen again, starting the cycle all over again.

Hubble’s observations revealed that twice as many novae appeared near the black hole’s stream compared to other regions in the same galaxy.

The black hole at the center of the massive elliptical galaxy M87 is surrounded by a disk of swirling material. As this material falls into the black hole, it feeds a jet that extends 3,000 light-years into space.

Catching this jet would be disastrous for anything in its path, but new findings show that even being near it seems dangerous.

Scientists have noticed that stars near the jet are more likely to explode as novae, probably because the jet pushes hydrogen toward the stars, speeding up the process that leads to these explosions.

One theory is that the jet somehow directs hydrogen towards white dwarfs, causing them to erupt more often.

However, it is unclear how exactly this could work. Scientists have considered the possibility that the jet is heating the stars, causing them to spill more hydrogen onto their white dwarfs, but the amount of heat does not seem to be enough to explain the increase in novae.

Michael Shara, a co-investigator at the American Museum of Natural History in New York, mentioned that scientists had previously suspected increased activity around the M87 jet, but Hubble’s observations provided much more evidence and statistical significance than ever before.

Hubble observes the galaxy M87 shortly after its launch in 1990. Early observations made with the telescope’s faint object camera showed unusual activity around the black hole, but the view was too narrow to draw firm conclusions.

Now, thanks to newer, more advanced cameras, Hubble was able to capture a broader image of M87, which led to this important discovery.

For nine months, Hubble closely monitored the galaxy, visiting every five days to track exploding stars. In total, 94 novae were observed in the area that Hubble’s camera could cover.

The data showed a clear pattern: More novae exploded near the jet than anywhere else in the galaxy. The finding was so clear that, as Shara put it, “you don’t need statistics to see that there is an excess of novae along the jet.”

The discovery highlights Hubble’s unique ability to peer deep into distant galaxies and discover phenomena that ground-based telescopes cannot see. Novas are quite common in the universe – one erupts in M87 every day.

Considering that there are over 100 billion galaxies in the visible universe, this means that about a million new galaxies explode in the universe every second.

The findings open new questions about the interactions between black hole jets and their host galaxies, and what this means for our understanding of the Universe.

Scientists like Chiara Circosta, an ESA research fellow, believe these observations are crucial to expanding our understanding of how jets from supermassive black holes can influence star formation and other cosmic events.

Source: European Space Agency.