Skip to main content

What is an accretion disk?

An accretion disk is an astronomical term that refers to the rapidly spiraling  matter that is in the process of falling into an astronomical object. In principle, any  star could have  an accretion disk, but in practice, accretion disks are often associated with highly collapsed stars such as black holes or  neutron stars. 


The matter that serves as the base of the accretion disk can be obtained when a star passes through a region where the  interstellar matter is thicker than normal. Normally, however, a star gets an accretion disk from a companion star.  When two stars  orbit each other, there is an invisible figure eight around the two stars, called the Roche lobes.  The Roche lobes represent all the points in space where the gravitational potential from each star is equal.  Therefore any matter on the Roche lobes could just as easily fall into either star. If one star in a binary system becomes larger than the Roche lobes, matter will fall from it onto the other star, forming an accretion disk.

The matter falling into a collapsing star hole tends to form a disk because a spherical  mass of gas that is spinning will tend to flatten out.  The faster it is spinning, the flatter it gets. So, if the falling material is orbiting the central mass, the spinning flattens the matter into an accretion disk. 

Black holes are objects that have  collapsed to the point that nothing, not even  light, can escape the incredible  force of their gravity. Because no light can escape, however, there is no way to directly observe it. However, if the  black hole has an accretion disk, we can observe  the black hole indirectly by observing the accretion disk, which will emit x rays.  Without accretion disks there would be little hope of astronomers ever observing black hole.

 Accretion disks can also occur with a  white dwarf in a binary system.  A white dwarf is a collapsed star that is the final stage in the evolution of stars similar to the  Sun. White dwarfs contain as much mass as the Sun, compressed to about the size of  Earth. Normally the nuclear reactions in a white dwarf have  run out of fuel, but the  hydrogen from the accretion disk falling onto a white dwarf fuels additional nuclear reactions.  White dwarfs have  some unusual properties that do not allow them to expand slowly to release the  heat pressure generated by these nuclear reactions.  This heat pressure therefore builds up until the surface of the whited dwarf explodes.  This type of explosion is called a  nova (not to be confused with a  supernova), and typically releases as much  energy in the form of protons in less than a year as the Sun does in 100,000 years.

Comments

Popular posts from this blog

Hyper Automation (New Technology)

Automation is nothing but an amalgamation of two super technologies of this error RPC and machine learning understanding the automation mechanisms and how it is controlled and coordinated using machine learning MBA main Circus of the screen in the year 2020 automation is employed to have a major macroeconomic implication on the market hence top companies need to give up for this convergence in demographic shapes for now company Wipro and Infosys are experimenting with this technology but other companies are not very far behind..

How ASPs works?

The Web and the Internet began to really heat up and receive significant media exposure starting around 1994. Initially, the Web started as a great way for academics and researchers to distribute information; but as millions of consumers flocked to the Internet, it began to spawn completely new business models. Three good examples of innovative models include:   • Amazon - Amazon (which opened its doors in July, 1995) houses a database of millions of products that anyone can browse at any time. It would have been impossible to compile a list this large in any medium other than the Web.   • Ebay - Online auctions make it easy and inexpensive for millions of people to buy and sell any imaginable item. It would be impossible to do this at a reasonable cost or in a timely manner with any medium other than the Web.   • Epinions - Thousands of people contribute to a shared library of product reviews. One of the Web's greatest strengths is its worldwide view a...

WHY DO WE SLEEP AND DREAM?

•We spend about one-third of our lives sleeping.  •Why do we invest so much time in sleep?  •The most straight forward answer is that, sleep is restorative, and it replenishes the body's energy stores.  •However, intense neural activity during rapid eye movement (REM) sleep, the stage in which most dreams occur, suggests there may be more to the story.  •One theory, which by far has the largest body of evidence, is that sleep plays a critical role in learning and consolidating memories.  •It is probably why infants and toddlers need up to 14 hours of sleep a day, with half of it spent in REM sleep.  •In adults, dreams may also play a role in brain plasticity and learning, which is why sleep-deprived adults perform worse in memory tests and tasks.