What is black hole? It is actually a particular region in space when the gravitational pull is so strong that even the light can’t pass through it.
This gravitational pull is generated because matter is pressed into a tiny space. Because no light can pass through it, therefore it looks invisible. However, with the help of special telescopes, it can be seen.
When a black hole engulfs a star, it breaks it apart. When star passes within some distance of a black hole, it could get close enough that it could be swallowed up by the black hole.
The gravitational force of black hole is so powerful that the approaching star gets stretched and torn apart. This process of star destruction is called “stellar tidal disruption” and stellar material is compressed and pulled in. During this process, high amount of energy is released and surrounding is brightened with this flare.
This huge flare of light echoes through space and could last for months or even years to cool down the gases of destroyed star. During this process, intense ultraviolet and x-ray light is also emitted and can destroy everything which comes into its way.
Scientists have observed that intense wind in the neighborhood of black hole V404 Cygni, which is located around 8,000 lights year away.
V404 Cygni is a black hole which is close to Earth. This black hole is around 10 times the mass of the sun. In June 2015 it engulfed the material of nearby star and as a result bright outburst happened after living in dormancy for around 25 years. Each flash of light was intense equivalent to power of 1000 suns. Its intense wind had very high speed of 3,000 Km per second which allowed it to escape from the gravitational field of black hole. The material which was expelled due to wind formed a nebula.The first direct image of black hole will be published later this year. The image of its event horizon was captured last year by Event Horizon Telescope (EHT]. This telescope contains global network of very powerful telescopes.
Reference:
1- https://www.quora.com/What-would-happen-if-a-black-hole-collided-with-a-neutron-star