|   | 
Credit & Copyright: April Hobart,  
CXC  
  
 
Explanation:
In the center of a swirling whirlpool of hot gas  
is likely a beast that has never been seen directly: a  
black hole.    
  
Studies of the bright light emitted by the  
swirling gas frequently indicate not only that a  
black hole is present, but also likely attributes.    
  
The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickering  
at a rate of 450 times a second.    
  
Given a  
previous mass estimate for the   
central object of seven times the mass of our  
Sun, the rate of the  
  
fast flickering can be  
explained by a black hole  
that is rotating very rapidly.    
  
What physical mechanisms actually cause the flickering -- and a slower quasi-periodic  
oscillation (QPO) -- in  
  
accretion disks surrounding  
black holes and  
neutron stars remains a topic of much research.  
  
  
  
    
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: black hole - accretion disk
Publications with words: black hole - accretion disk
See also:
- APOD: 2025 September 24 Á GW250114: Rotating Black Holes Collide
- APOD: 2025 May 9 Á IXPE Explores a Black Hole Jet
- APOD: 2025 May 6 Á The Doubly Warped World of Binary Black Holes
- APOD: 2025 May 4 Á Spin up of a Supermassive Black Hole
- APOD: 2024 November 24 Á Journey to the Center of the Galaxy
- APOD: 2024 October 1 Á Porphyrion: The Longest Known Black Hole Jets
- APOD: 2024 June 16 Á Animation: Black Hole Destroys Star
