21 December 2011

Quasar Image Observed by Hubble Telescope

Image credit: NASA, ESA, J.A. Muñoz (University of Valencia)

This picture is taken by Hubble telescope and shows an observed disc around a black hole. This disc is called Quasar (quasi-stellar radio source), and is a brightly glowing disc of matter in a compact region in the center of a massive galaxy surrounding its central supermassive black hole.

Read more about black hole here.

A team of astronomers from NASA/ESA used Hubble telescope to observe the above picture. They used gravitational lensing to immense increase to the power of the telescope and they were able to measure the disc’s size and the temperature across different parts of the disc.

A quasar accretion disc has a typical size of a few light-days, or around 100 billion kilometers across, but they lie billions of light-years away. This means their apparent size when viewed from Earth is so small that we will probably never have a telescope powerful enough to see their structure directly,” explains Jose Muñoz, the lead scientist in this study.

What is a Quasar?

Quasars or Quasi-Stellar Radio Sources are certain objects emitting radio waves but not all similar objects emit radio waves. These objects are termed Quasistellar objects or QSOs. All of these are often called Quasrs. These objects are not stars but they are the very bright centers of some distant galaxies, where some sort of energetic action is accruing, and mostly due to the presence of a supermassive black hole at the center of galaxy.

When matter fall into the supermassive black hole, producing a very hot region with huge energies (Quasar).

Image credit: European Southern Observatory (ESO)

Some quasars produce radio wave when the electrons near the center accelerated to speeds near the speed of light and in the presence of a magnetic field, they discharge radio waves. They can be a trillion times brighter than the sun. Quasars are from great distance from the Earth and their energy takes billions of years to reach Earth. That is why study of quasars can provide scientists information about the early stage of the universe.

Astronomers believe that Quasars and Active galaxies are related together. Galaxies which have extraordinary variability and evidence of strong interaction in their galactic nuclei (AGN or the central region) are called Active galaxy.

One more thing you should know about Quasars is that they have very great redshift. Redshift happens when light seen coming from an object is proportionally increased in wavelength.

This really amazing that today scientists are able to observe Quasars as they are the brightest and most distant objects in the universe.