Free Astronomy Magazine November-December 2024

48 NOVEMBER-DECEMBER 2024 “But Hubble has shown this en- hanced activity with far more exam- ples and statistical significance than we ever had before.” Shortly after Hubble’s launch in 1990, astronomers used its first-gen- eration Faint Object Camera (FOC) to peer into the center of M87 where the monster black hole lurks. They noted that unusual things were hap- pening around the black hole. Al- most every time Hubble looked, astronomers saw bluish “transient events” that could be evidence for novae popping off like camera flashes from nearby paparazzi. But the FOC’s view was so narrow that Hubble astronomers couldn’t look away from the jet to compare with the near-jet region. For over two decades, the results remained myste- riously tantalizing. Compelling evidence for the jet’s in- fluence on the stars of the host gal- axy was collected over a nine-month interval of Hubble observing with newer, wider-view cameras to count the erupting novae. This was a chal- lenge for the telescope’s observing schedule because it required revisit- ing M87 precisely every five days for another snapshot. Adding up all of the M87 images led to the deepest images of M87 that have ever been taken. Hubble found 94 novae in the one-third of M87 that its camera can encompass. “The jet was not the only thing that we were looking at — we were looking at the entire inner galaxy. Once you plotted all known novae on top of M87 you didn’t need statistics to convince yourself that there is an ex- cess of novae along the jet. This is T his is an artist’s concept looking down into the core of the giant elliptical galaxy M87. A supermas- sive black hole ejects a 3,000-light- year-long jet of plasma, traveling at nearly the speed of light. In the fore- ground, to the right is a binary star system. The system is far from the black hole, but in the vicinity of the jet. In the system an aging, swelled- up, normal star spills hydrogen onto a burned-out white dwarf compan- ion star. As the hydrogen accumu- lates on the surface of the dwarf, it reaches a tipping point where it ex- plodes like a hydrogen bomb. Novae frequently pop-off throughout the giant galaxy, but those near the jet seem to explode more frequently. So far, it’s anybody’s guess why black hole jets enhance the rate of nova eruptions. [NASA, ESA, Joseph Olm- sted (STScI)]