Black Holes & Spacetime
Tidal Disruption Events
A tidal disruption event is a star torn apart when it strays too close to a supermassive black hole.
The debris can produce a bright flare lasting months, making otherwise quiet black holes visible.
- Observe
A galaxy's center flares and fades over months.
- Measure
Brightness in ultraviolet, optical and X-ray light, and how it evolves.
- Model
Simulations of a star being stretched into a stream of gas.
- Explain
A star was destroyed, briefly lighting up a dormant black hole.
What is it?
When a star passes close enough to a supermassive black hole, the difference in gravity across the star, called tidal force, can exceed the star's own gravity and pull it apart. Roughly half of the debris is thought to remain bound and fall back toward the black hole, forming a hot, glowing disk.
Such events are rare in any single galaxy, on the order of once in tens of thousands of years, so astronomers rely on surveys that watch many galaxies. Some produce jets. What powers the visible light in many events is still debated.
How does it happen?
- Stage 1Star approaches a supermassive black hole
- Stage 2Tidal force exceeds the star's self-gravity
- Stage 3Star is stretched and disruptedStreams of gas form
- Stage 4Debris forms a glowing accretion structure
What do we actually observe?
- Central flare
- A very blue, hot flare from the center of a galaxy that had been quiet.
- Fading pattern
- The brightness often declines smoothly over months to years.
- Spectrum
- Broad lines from hydrogen and sometimes helium mark the debris.
- Jets
- A minority of events show relativistic jets seen in radio and X-rays.
How do scientists detect it?
- Optical transient surveys. ASAS-SN and the Zwicky Transient Facility find many TDEs.
- X-ray missions. Swift, XMM-Newton and eROSITA identify X-ray flares from galaxy centers.
Why does it matter?
- They light up supermassive black holes that are otherwise dormant.
- They give a way to measure black-hole masses and study accretion in a clean setting.
The SpaceWeatherTracker connection
Accretion disks are magnetized plasma, and understanding how magnetic fields launch jets connects to the same plasma physics used to study the Sun's eruptions.
This is an explainer. SpaceWeatherTracker does not show live data for this phenomenon; see the “Space Phenomena Now” section on the hub for what is currently monitored.
Related phenomena
Primary family: Black Holes & Spacetime
Tidal Disruption Events: common questions
What is a tidal disruption event?
The destruction of a star by the tidal forces of a supermassive black hole, producing a bright flare.
Does the black hole eat the whole star?
About half of the star's material is thought to stay bound and fall toward the black hole; the rest is flung away.