Microlensing

News: A recent study used microlensing to measure the mass of a rogue planet, meaning a planet that does not orbit a star.

About Microlensing

• Microlensing is a method astronomers use to find planets far away from Earth.
• Working mechanism
  • It is based on Einstein’s theory of gravity, which says that massive objects like stars can bend light.
  • Microlensing occurs when a star passes in front of another distant star as seen from Earth.
  • The gravity of the front star bends and magnifies the light from the background star.
    • This bending of light causes the star to appear much brighter for a short period of time.
  • When the alignment is nearly perfect, the light forms a circular shape called an Einstein ring.
    • The brightness of the star increases, reaches a peak, and then slowly decreases over weeks or months.
• How microlensing detects planets
  • If the lensing star has a planet, the planet’s gravity also bends the light.
  • This produces a short and sudden spike in brightness during the microlensing event.
  • The spike can last from a few hours to a few days.
  • By studying this spike, scientists can estimate the planet’s mass and its distance from the star.
• Advantages of microlensing
  • Microlensing is the only known method capable of discovering planets at truly great distances from the Earth and is capable of finding the smallest of exoplanets.
  • This method is effective for finding planets that orbit far from their stars.
  • Microlensing can detect free-floating planets that do not orbit any star.
  • Many stars can be observed at the same time, increasing the chance of detection.
• Disadvantages of microlensing
  • Each microlensing event happens only once and cannot be observed again.
  • Planets discovered by microlensing cannot be studied in detail after the event ends.
  • The distance to the detected planet is only roughly estimated.
  • Microlensing events are rare and depend on precise alignment of stars and planets.