Context:  Six exoplanets orbiting around a nearby bright star (HD 110067) in the Coma Berenices constellation have been discovered.   

Discovery of Six Exoplanets 

• The planets have radii between Earth and Neptune. 
• NASA’s Transiting Exoplanet Survey Satellite (TESS) first discovered two exoplanets orbiting the star in 2020.
  • TESS is a space telescope for NASA’s Explorer program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the Kepler mission.
• Planets with radii between that of the Earth and Neptune (referred to as ‘sub-Neptunes’) are found in close-in orbits around more than half of all Sun-like stars.

What are Exoplanets?

• The word “exoplanet” is derived from the term “extrasolar planet.“
• Exoplanets are planets that orbit stars other than the sun and thus exist outside the solar system. 
• Currently, the closest exoplanet to Earth is Proxima Centauri b, which orbits the star Proxima Centauri and is located 4 light-years away.

Types:

• Hot Jupiters: Hot Jupiters are gas giant exoplanets that orbit close to their stars and complete a full orbit in just a few Earth days. 
• Terrestrial exoplanets: Terrestrial exoplanets are roughly Earth-size worlds outside the solar system composed of rock, silicate, water and carbon. 
• Super-Earths or mini Neptunes: Super-Earths, alternatively known as mini-Neptunes, are planets that are up to twice the size of Earth.
• Rogue Exoplanets: They are also known as isolated planetary-mass objects and free-floating planets, which are worlds outside the solar system that are not gravitationally bound to stars. 

About HD 110067:

• HD 110067 is a bright star in the Coma Berenices constellation (around 100 light-years away), visible from Earth’s Northern Hemisphere.

Significance of Discovery: 

• A study published in Nature has calculated the orbit details, along with estimates of their masses and densities, which offer clues about the compositions of the planets’ atmospheres.

News Source: The Hindu