Astronomers are revealing details of the massive star ASASSN-14li that was swallowed by a black hole, challenging previous theories and hinting at new methods of space exploration. Researchers have completed a comprehensive forensic examination of a star that broke apart when it dared to get too close to a supermassive black hole, then blasting its interior into space.

NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton investigated the amount of nitrogen and carbon near the black hole known to be tearing apart the star. Astronomers believe these elements formed inside the star before it disintegrated as it approached the black hole.

“We’re seeing the essence of what used to be a star,” said John Miller of the University of Michigan, who led the study. “The elements left behind are clues we can follow to understand which star died.”

This artist’s illustration shows the aftermath of a “tidal disruption event” (TDE) called ASASSN-14li, in which a star broke apart after coming too close to a supermassive black hole. After the star broke apart, some of its gas (red) swirled around it and fell into the black hole, while some of the gas was blown out by the wind (blue). Credits: NASA/CXC/University of Michigan/J. Miller et al; Illustration: NASA/CXC/M.Weiss

Tidal Cuts: A Closer Look

In recent years, astronomers have found many examples of “tidal disruptions,” which occur when the gravitational forces of a massive black hole destroy a star. This causes the star’s remnants to heat up, causing a flare often seen in optical and ultraviolet light and in X-rays. This event, called ASASSN-14li, stands out for several reasons.

At the time of its discovery in November 2014, it was the closest tidal disruption to Earth (290 million light-years) discovered in nearly a decade. Because of this proximity, ASASSN-14li provided an extraordinary level of detail about the destroyed star. Miller’s team applied new theoretical models to make better predictions than previous studies about the amount of nitrogen and carbon around the black hole.

This animation shows what happens when an unlucky star gets too close to a monster black hole. Gravitational forces create intense tides that break the star into streams of gas. As the rear part of the stream leaves the system, the front part rotates back, surrounding the black hole with a disk of debris. This catastrophic event is called a tidal event. Image Credit: NASA Goddard Space Flight Center/Chris Smith (USRA/GESTAR)

The star in ASASSN-14li is therefore one of the largest, and probably the most massive, stars astronomers have ever seen torn apart by a black hole.

Value of ASASSN-14li

“ASASSN-14li is exciting because one of the most challenging things about tidal disruptions is being able to measure the mass of an ill-fated star, as we did here,” said co-author Enrico Ramírez-Ruiz of the University of California, Santa Cruz. . . . “Observing a massive star being destroyed by a supermassive black hole is fascinating because more massive stars are expected to be much less common than less massive stars.”

Earlier this year, another team of astronomers reported the “Scary Barbie” event, in which a star they estimated to be about 14 times the mass of the Sun was destroyed by a black hole. However, it has not yet been confirmed that this is a tidal disruption, as the estimate of the star’s mass is based primarily on the brightness of the flare rather than a detailed analysis of the material around the black hole as in the ASASSN example. 14li.

Another exciting aspect of the ASASSN-14li result is what it means for future research. Astronomers have seen medium-sized stars like ASASSN-14li in a star cluster containing the supermassive black hole at the center of our galaxy. Therefore, the ability to estimate the stellar masses of stars destroyed by tides potentially provides astronomers with a way to determine the existence of star clusters around supermassive black holes in more distant galaxies.

Before this study, there was a strong possibility that the elements seen in X-rays could come from gas released during previous explosions of a supermassive black hole. But the pattern of elements analyzed here appears to come from a single star.

An earlier paper published in 2017 by Chenwei Yang of the University of Science and Technology in Hefei, China, used NASA’s Hubble Space Telescope to show that ASASSN-14li contains more nitrogen than carbon, but smaller amounts than Miller’s. He used ultraviolet data taken from . The team discovered this using X-ray data. These authors found that this star is only 0.6 times the mass of the Sun. Source