California: Astronomers using NASA’s Hubble Space Telescope have made an unexpected discovery in the M87 galaxy. The research team, led by Alec Lessing of Stanford University, found that stars near the jet of a supermassive black hole are experiencing increased rates of stellar eruptions, known as novae.
Located 53 million light-years away, the black hole at the core of M87 weighs in at a staggering 6.5 billion solar masses. It launches a plasma jet stretching over 3,000 light-years, moving close to the speed of light. Despite being outside the jet’s destructive path, nearby double-star systems are apparently in a volatile environment that causes them to erupt more frequently.
Researchers discovered that twice as many novae occur along the jet’s path compared to other regions of the galaxy, confounding scientists. Lessing conveyed that, “We don’t know what’s going on, but it’s a very exciting finding.”
Novae occur when hydrogen from a companion star is transferred onto a white dwarf, eventually triggering an explosion similar to a nuclear bomb. The white dwarf survives the event, only to begin the cycle anew.
The Hubble observations spanned nine months, revealing 94 novae in one-third of M87, with a noticeable concentration along the jet’s path. The findings suggest that the jet may be influencing the star systems in its vicinity, potentially speeding up hydrogen transfer rates, which in turn causes the white dwarfs to erupt more frequently.
Lessing explained that, “It’s not clear that it’s a physical pushing. But, something might be doubling the mass transfer rate onto the white dwarfs near the jet.” Another hypothesis suggests the jet could be heating the dwarf’s companion star, but calculations indicate this heating is insufficient to fully explain the phenomenon.
Co-investigator Michael Shara of the American Museum of Natural History in New York City pointed out that the excess of novae around the M87 jet had been suspected in the past. The groundbreaking observations underscore Hubble’s unique capabilities. Ground-based telescopes lack the resolution to detect novae against the bright core of M87, making Hubble the only instrument capable of producing these insights.
The discovery is an exciting step toward understanding the powerful relationship between black holes and their host galaxies. However, the mystery of why stars near the jet erupt more often remains unsolved.