The star had a rough go of it.
Around the time multicellular organisms started evolving on Earth, the black hole at the center of a faraway galaxy devoured a star that got a little too close. The star’s destruction created an explosion of radio waves that spent half-a-billion years hurtling through space. In the 1990s, a tiny fraction of those waves landed on the dishes of the Very Large Array Radio Telescope facility in the New Mexico desert. No one noticed until two high school students — Ginevra Zaccagnini and Jackson Codd — spotted an unexpected pattern while looking through archival data as part of a research internship at Harvard.
The observation is only the second of its kind.
The star got ‘spaghettified’ after wandering too close to a black hole
Black holes are so dense that not even light can escape their grasp, so it’s no surprise that a star can easily fall into the black hole that lies at the center of its galaxy. By all accounts, it’s a spectacular sight. The extreme gravity surrounding the black hole “shred[s] these unlucky stars, causing them to be squeezed into thin streams,” according to Vikram Ravi, an astronomer at the California Technical Institute and lead author on the paper reporting the observation. Astronomers call this process “spaghettification” because, well, the thin streams of star stuff resemble spaghetti noodles. "This is a really messy process. The stars don't go quietly!" Ravi said in a statement.
The remains of the shredded star glow in far more colors of light than humans can see. Since the first observation in the 1980s, Astronomers have witnessed black holes gobble up about 100 stars. They saw all but two of those stellar feasts — formally known as tidal disruption events (TDEs) — by scanning the skies for visible (or nearly visible) light or for x-rays. The data behind the recent observation came as radio waves, which have much longer wavelengths. Researchers are interested in these discoveries for their own sake and because they give astronomers a rare opportunity to study black holes themselves. “TDEs basically turn flashlights onto these extreme regions at the centers of galaxies that we would not otherwise be able to see," according to Jean Somalwar, a graduate student in Ravi’s lab.
The discovery was a long time coming
The first signs of the newly discovered TDE, called J1533+2727, came while Zaccagnini and Codd were analyzing data from the National Radio Astronomy Observatory's Karl G. Jansky Very Large Array, which is located about two hours from Albuquerque, New Mexico. The high school students realized an object that burned brightly in the 1990s had grown significantly weaker by 2017. Measurements taken in the 1980s by a similar telescope in Green Bank, West Virginia, showed that the object had once been about 500 times brighter than it was in 2017.
Though astronomers have suspected since the 1980s that TDEs occur, the first one wasn’t spotted with a radio telescope until 2020. The recent sighting of J1533+2727 could be a sign that the floodgates are opening thanks to a deluge of new data. Hannah Dykaar, an astronomer at the University of Toronto and co-author on the paper, said that “[a]n unprecedented amount of radio observations are now becoming available, positioning us to discover many more sources like this one." That’s good news for anyone interested in learning about the supermassive black holes that lie at the center of each and every galaxy — including ours.