Why in News

The Habitable-zone Planet Finder (HPF) has confirmed its first planet (exoplanet) called G 9-40b, orbiting a nearby low mass bright M-dwarf star (100 light years from Earth) with an orbital period of 6 Earth-days.

  • Earlier, NASA’s Kepler mission had observed a dip in the host star’s light, suggesting that the planet was crossing in front of the star during its orbit. To confirm the HPF was used.

Key Points

  • G 9-40b: G 9-40b is amongst the top 20 closest transiting planets known.
  • Habitable-zone Planet Finder : HPF is an astronomical spectrograph, built by Penn State University scientists, and recently installed on the 10m Hobby-Eberly Telescope at McDonald Observatory (US).
    • The HPF searches for exoplanets by using the Doppler effect.
    • A spectrograph is an instrument that splits light into its component wavelengths. Scientists measure the properties of light over a specific portion of the spectrum, and draw conclusions on what is responsible for the trends they observe.
    • The HPF provides the highest precision measurements of infrared signals from nearby low-mass stars, and astronomers use it to validate the candidate planet by excluding all possibilities of contaminating signals to a very high level of probability.
    • It is designed to detect and characterise planets in the habitable-zone also known as ‘Goldilocks zone’- the region around the star where a planet could sustain liquid water on its surface.
    • HPF is currently surveying the nearest low-mass stars, also called M-dwarfs, which are the most common stars in the galaxy - with the goal of discovering exoplanets in our neighborhood.

Doppler Effect

  • An increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move towards (or away from) each other.
  • The effect causes the sudden change in pitch noticeable in a passing siren, as well as the red shift seen by astronomers.


  • An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmation of detection of exoplanet occurred in 1992.
  • Exoplanets are very hard to see directly with telescopes. They are hidden by the bright glare of the stars they orbit.
  • So, astronomers use other ways to detect and study exoplanets such as looking at the effects these planets have on the stars they orbit.


  • M dwarf or M-type star, also called Red Dwarf Star are the most numerous type of star in the universe and the smallest type of hydrogen-burning star.
  • These have masses from about 0.08 to 0.6 times that of the Sun.
  • In the Milky Way Galaxy, about 70% of the stars are red dwarfs.