- In the recent past, astronomers have discovered that many other stars have planets going around them, like our Solar System.
- Till now, around 5000 such exoplanets have been detected.
- Recently, Aritra Chakrabarty, a postdoctoral researcher at Indian Institute of Astrophysics (IIA), Bangalore, developed a detailed three-dimensional numerical method and simulated the polarization of exoplanets.
- Just like the Solar-planets, exoplanets are slightly oblate due to their rapid spin rotation.
- Further, depending on its position around the star, only a part of the planetary disk gets illuminated by the starlight.
- This asymmetry of the light-emitting region gives rise to non-zero polarization.
- The polarization at different wavelengths is sufficiently high and hence can be detected even by a simple polarimeter if the starlight is blocked.
- It helps study the atmosphere of the exoplanets along with its chemical composition.
- Unlike the traditional and popular methods such as Transit Photometry and Radial Velocity methods that can detect planets that are viewed almost edge-on only, this polarimetric method can detect and probe exoplanets orbiting with a broad range of orbital inclination angles.
What are exoplanets?
- Exoplanets are planets that lie beyond our solar system.
- Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center and are untethered to any star.
- The first possible evidence of an exoplanet was noted in 1917, but was not recognized as such.
- The first confirmation of detection occurred in 1992.
- This was followed by the confirmation of a different planet, originally detected in 1988.
- 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 these distant planets.
- They search for exoplanets by looking at the effects these planets have on the stars they orbit.