Black Holes Don't Always Destroy Stars. Here's Why.

Topic: Astronomy

Astronomers at Syracuse University discovered that stars can survive encounters with supermassive black holes and even return for more close passes. They found that the star's internal structure, including its spin rate, plays a crucial role in determining how much material is stripped away during each encounter.

Most galaxies have a supermassive black hole at their center. These enormous objects can weigh millions or even billions of times more than our sun. When a star passes close to one of these black holes, it's torn apart by the strong gravitational forces. This event is called a tidal disruption event (TDE).

In some cases, the star doesn't get completely destroyed and returns for additional close encounters with the black hole. These events are known as repeating partial TDEs (rpTDEs). By studying these events, astronomers can learn more about the properties of stars and black holes.

A team of researchers from Syracuse University led by doctoral student Ananya Bandopadhyay discovered that some rpTDEs behave differently than expected. Instead of producing similar flares on each return, they become steadily fainter. The researchers used hydrodynamical simulations to study this phenomenon and found that the star's internal structure, including its spin rate, plays a crucial role in determining how much material is stripped away during each encounter.

The team suggests that if the star was initially rapidly rotating before its first close encounter with the black hole, it could explain why some rpTDEs exhibit dimmer peak luminosities during each successive outburst. This finding provides strong indirect evidence for the operation of the Hills mechanism in seeding the stars in rpTDEs.

The study, published in The Astrophysical Journal, was led by Ananya Bandopadhyay and involved researchers from Syracuse University and other institutions.

Why It Matters

Understanding how black holes interact with stars can help us better grasp the behavior of these cosmic objects. This knowledge can also have implications for our understanding of the formation and evolution of galaxies in the universe.

Key Facts

• Most galaxies have a supermassive black hole at their center, weighing millions or billions of times more than our sun.
• Stars can survive encounters with supermassive black holes and return for additional close passes.
• Repeating partial TDEs (rpTDEs) occur when a star loses only part of its mass during each encounter with the black hole.
• The star's internal structure, including its spin rate, plays a crucial role in determining how much material is stripped away during each encounter.
• The study suggests that the Hills mechanism could be responsible for seeding stars in rpTDEs.

Key Terms

Supermassive Black Hole

A massive object at the center of a galaxy with gravity so strong it warps space and time.

Repeating Partial Tidal Disruption Event (rpTDE)

An event where a star loses only part of its mass during each close encounter with a black hole.

Implications

Understanding how black holes interact with stars can help us better grasp the behavior of these cosmic objects. This knowledge can also have implications for our understanding of the formation and evolution of galaxies in the universe.