Chemical Signatures Detected on Exoplanet K2-18b
Context:
Recently, some of the important chemical signatures of the exoplanet K2-18b were discovered by NASA’s James Webb Space Telescope (JWST). This finding paves the way for potentially identifying conditions supportive of life.
Relevance:
GS-03 (Science and technology)
Key Highlights:
- New Discovery: JWST detected Dimethyl Sulfide (DMS) and Dimethyl Disulfide (DMDS)—gases associated with marine phytoplankton on Earth.
- Previous Findings: Methane and carbon dioxide had already been identified in K2-18b’s atmosphere.
- Concentration: DMS and DMDS levels are thousands of times higher than on Earth.
- Method Used: Transit Method – JWST detected a dip in stellar brightness when K2-18b passed in front of its star.
- Planet Type: K2-18b is now classified as a Hycean exoplanet – an ocean-covered planet with a hydrogen-rich atmosphere.
- Statistical Accuracy: Achieved three-sigma confidence level (only 0.3% chance of error).
About K2-18b:
- It is also known as EPIC 201912552 b.
- It is an exoplanet orbiting the red dwarf K2-18, located 124 light-years (38 pc) away from Earth.
- Size: 8.6 times Earth’s mass and 2.6 times its diameter.
What is James Webb Space Telescope (JWST)?
- JWST is the largest telescope in space which is designed to conduct infrared astronomy.
- Purpose: Study early universe, star and planet formation.
- It was launched on 25 December 2021.
- Orbit: At Lagrange Point-2 (L2), 1.5 million km from Earth.
- The telescope is named after James E. Webb, who was the administrator of NASA from 1961 to 1968 during the Mercury, Gemini, and Apollo programs.
Prelims Practice Question:
Q. Which of the following chemical compounds, recently detected on exoplanet K2-18b, are commonly produced by marine phytoplankton on Earth?
A) Methane and Carbon Monoxide
B) Dimethyl Sulfide and Dimethyl Disulfide
C) Hydrogen Peroxide and Ozone
D) Ammonia and Sulfur Dioxide
Answer: B) Dimethyl Sulfide and Dimethyl Disulfide
