Astronomers have captured the last moments of a star just before it was ripped apart by a black hole. The violent occurrence-called a tidal disruption event-created a blast of light seen just 215 million light years from Earth, the closest such flare recorded to date. The research is published in the Monthly Notices of the Royal Astronomical Society.
"The idea of a black hole ’sucking in’ a nearby star sounds like science fiction. But this is exactly what happens in a tidal disruption event," explained Matt Nicholl, a lecturer and Royal Astronomical Society research fellow at the University of Birmingham, UK, and the lead author on the new study.
To get a detailed look at just what happens when a star is devoured by a monstrous black hole, researchers pointed the European Southern Observatory’s Very Large Telescope ( VLT ) and New Technology Telescope ( NTT ) at a new flash of light that occurred close to a supermassive black hole last year. Followup observations occurred over a six-month period at multiple telescopes around the world, including the Center for Astrophysics Harvard & Smithsonian’s MMT , located at the Fred Lawrence Whipple Observatory in Amado, Arizona.
Tidal disruption events-in which stars experience spaghettification --are powerful and bright, which should make them easy to study. "A tidal disruption event results from the destruction of a star that strays too close to a supermassive black hole," said Edo Berger, astronomer, CfA, and one of the authors on the study. "In this case the star was torn apart with about half of its mass feeding-or accreting-into a black hole of one million times the mass of the Sun, and the other half was ejected outward."
These rare events are often obscured by a thick curtain of dust and debris, which has made it difficult for astronomers to see what’s happening, until now. AT2019qiz-the tidal disruption event the team was studying-was found shortly after the star was ripped apart, making it easier to analyze. "Because we caught it early, we could actually see the curtain of dust and debris being drawn up as the black hole launched a powerful outflow of material with velocities up to 10,000 km/s," said Kate Alexander, NASA Einstein Fellow at Northwestern University. "This is a unique ’peek behind the curtain’ that provided the first opportunity to pinpoint the origin of the obscuring material and follow in real time how it engulfs the black hole."
The newly discovered tidal disruption event will help scientists to better understand supermassive black holes and how matter behaves around them. "AT2019qiz is the nearest tidal disruption event discovered to date, and hence, incredibly well-observed across the electromagnetic spectrum. This is the first case in which we see direct evidence for outflowing gas during the disruption and accretion process that explains both the optical and radio emissions we’ve seen in the past," said Berger. "Until now, the nature of these emissions has been heavily debated, but here we see that the two regimes are connected through a single process. This event is teaching us about the detailed physical processes of accretion and mass ejection from supermassive black holes."
Reference: "An Outflow Powers the Optical Rise of the Nearby, Fast-Evolving Tidal Disruption Event AT2019qiz," Nicholl et al, Monthly Notices of the Royal Astronomical Society .
About Center for Astrophysics
Harvard & Smithsonian (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.