Galaxy GN-z11

In News

• The latest spectroscopic results from GN-z11 which is one of the distant and early galaxies has confirmed a complete absence of dust particles from its surroundings for an interim time period despite possessing a very high star formation rate.

About GN-z11 Galaxy

• It was first discovered in 2015 by the Hubble Space Telescope (HST).
• It is located approximately 32 billion light years away from the Earth.
• It has been in existence since the Universe was 400 million years old post the Big Bang event.

What are Galaxies?

• A galaxy starts to form by accumulation of hydrogen gas in the form of a very large cloud called a nebula.
• Eventually, growing nebula develop localised clumps of gas.
• These clumps continue to grow into even denser gaseous bodies, giving rise to formation of stars.
• The Sun is  one of a vast number of stars within a galaxy and the Milky Way is only one of the billions of galaxies in the universe. 
• Astronomers generally classify galaxies into three major categories: spiral – like Milky Way – elliptical, and irregular.

Star Formation Process

• Stars are the most widely recognized astronomical objects, and represent the most fundamental building blocks of galaxies. 
• The age, distribution, and composition of the stars in a galaxy trace the history, dynamics, and evolution of that galaxy. 
• Stars are born within the clouds of dust and scattered throughout most galaxies.
• Turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction. 
• As the cloud collapses, the material at the center begins to heat up. Known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star.
• The process of star formation and the subsequent stellar evolution inevitably generates massive amounts of dust and makes the host galaxy opaque to some extent due to the apparent view of a thick veil around it. 
• This phenomenon has been missing in GN-z11’s behaviour, leaving astronomers amazed beyond measure.

Reasons Decoded by Scientists for this 

• Some of the possible reasons to explain this temporary disappearance of dust clouds are – the suppression of dust by reverse shocks from a supernovae explosion, destruction of dust by supernovae-triggered shocks, evacuation of dust by gaseous outflow driven by other stellar activity. 
  • A supernova is the explosion of a star. It is the largest explosion that takes place in space.
• Likewise, the re-emergence of the dust veil could be linked with the massive gravitation force possessed by GN-z11.

Source: PIB