New model explains how we see a massive black hole devours a star

What can happen to a star that wanders too close to the supermassive black hole in the center of its galaxy? Astrophysicists have been struggling to understand this diversity and assemble different pieces of the puzzle into a coherent model. 

But now thanks to a breakthrough study, published in Astrophysical Journal Letters, which reveals that the superstar will be torn apart by the black hole's gravity in a violent cataclysm called a tidal disruption event (TDE), producing a bright flare of radiation. The research provides a new theoretical perspective via a computer model developed by astrophysicists and looks at the consequence of a “superstar sucked into the supermassive”. 

The study led by theoretical astrophysicists at the University of Copenhagen's (UOC) Niels Bohr Institute and UC Santa Cruz (UCSC) provides a unified model that explains recent observations of these extreme events. “Only in the last decade or so have we been able to distinguish TDEs from other galactic phenomena, and the new model will provide us with the basic framework for understanding these rare events,” said co-author Professor Enrico Ramirez-Ruiz, chair of Astronomy at UCSC and Niels Bohr Professor at the UOC.

How big are black holes?
Black holes can be big or small. The largest black holes are called "supermassive." These black holes have masses that are more than 1 million suns together. In most galaxies, the central black hole is quiescent, not actively consuming any material and therefore not emitting any light. 

Illustration of emissions from a tidal disruption event shows in cross section what happens when the material from a disrupted star is devoured by a black hole. The material forms an accretion disk, which heats up and emits vast amounts of light and radiation. 

Illustration by Dr. Jane Lixin Dai / Niels Bohr Institute, University of Copenhagen

Tidal disruption events are rare, only happening about once every 10,000 years in a typical galaxy. When an unlucky star gets torn apart, however, the black hole is "overfed" with stellar debris for a while and emits intense radiation. “As the black hole is eating the stellar gas, a vast amount of radiation is emitted. The radiation is what we can observe, and using it we can understand the physics and calculate the black hole properties,” said lead a