Black Hole consuming a Star.

The Hubble Space Telescope has recorded a rare occurrence of a supermassive black hole devouring a star. Such events are infrequent, happening only a few times every 100,000 years in a galaxy with a dormant black hole at its center, but this specific event was captured by the telescope.

This sequence of illustrations created by an artist demonstrates how a black hole can consume a passing star. The image was created by NASA, ESA, and Leah Hustak from the STScI.

The fate of stars can be varied, with some ending their lives in a spectacular supernova explosion, others expanding and dissipating before shrinking to a small core, and very occasionally, some are torn apart and consumed by a massive black hole.

The destructive force of a black hole is a rare occurrence, happening only a few times every 100,000 years in a galaxy with a dormant black hole at its center. However, recently, the Hubble Space Telescope was able to capture such an event, where a star that came too close to a black hole, nearly 300 million light-years away, was devoured, resulting in a burst of light, known as AT2022dsb.

“Black holes consume their prey in a chaotic manner.”

The process of a star being torn apart by a black hole is known as a tidal disruption event. This is caused by the immense gravitational pull of a supermassive black hole. These massive black holes are located at the center of galaxies and can tear off layers of gas from a star that ventures too close. Eventually, the star is completely shredded, and its remains are pulled into a disk of matter surrounding the black hole, known as an accretion disk. The black hole feeds from this disk.

“Black holes are very messy eaters,” said Emily Engelthaler of the Harvard & Smithsonian Center for Astrophysics, during the American Astronomical Society meeting on January 12th. She further explained, “They consume the accretion disk, which is shaped like a doughnut, from the inside and emit radiation, causing the disk to puff up into a large doughnut shape.”

This research focused on the radiation emitted through the accretion disk during the Tidal Disruption Event. The researchers used the Hubble Space Telescope to observe ultraviolet light coming from the star and applied a method called spectroscopy to analyze the light’s wavelength and determine which elements were present. This provided insight into the intense and chaotic activity happening around the black hole. Additionally, Some of the radiation given off in these events travels away in the form of jets, but this study mainly focuses on the radiation that is coming through the accretion disk itself.

Tidal Disruption Events, where a star is devoured by a black hole, are extremely rare occurrences, happening only a few times every 100,000 years in a galaxy with a dormant black hole at its center.

Observing Tidal Disruption Events in the ultraviolet wavelength is difficult because this wavelength is easily blocked, making data collection challenging. A telescope outside of Earth’s atmosphere is necessary for such observations. “Ultraviolet is very bad at getting through atmospheres, which is great for us but terrible for observation. So we have to use a space telescope,” said Engelthaler.

The researchers were interested in studying how the star and the black hole evolved over time. To achieve this, they made a series of observations over several months. They discovered that the temperature in the accretion disk decreased with time and that the stellar winds moved away from the event towards us, at a speed of 20 million miles per hour, or 3 percent of the speed of light.

However, the researchers observed that the spectra collected were not stable and varied significantly over time. This could be due to the distance of the source being studied, which resulted in the signal becoming obscured by noise. Alternatively, it could be that the accretion disk around the black hole became thinner and the amount of material being pulled into the black hole decreased.

The researchers are still analyzing the data they have collected. Fellow researcher, Peter Maksym stated, “We really are still getting our heads around the event. You shred the star and then it’s got this material that’s making its way into the black hole. And so you’ve got models where you think you know what is going on, and then you’ve got what you actually see. This is an exciting place for scientists to be: right at the interface of the known and the unknown.”