Discovery of Circular Polarisation in Protostar

Summary of Discovery Related to Massive Protostar IRAS 18162-2048

An international team of astronomers, primarily from the Indian Institute of Space Science and Technology (IIST), has made a significant discovery regarding the protostar IRAS 18162-2048, located approximately 4,500 light years from Earth. This finding, published in The Astrophysical Journal Letters, represents the first detection of circular polarization in radio emissions from a massive protostar.

Key Points:

• Definition of Protostar: A protostar is an early phase in stellar evolution, characterized by the accumulation of gas and dust, leading to the eventual formation of a star.

• Discovery Details:

  • The research focused on IRAS 18162-2048, recognized as one of the largest and brightest protostellar jets, known as HH80-81, within the Milky Way galaxy.
  • Circular polarization refers to the phenomenon where the electric and magnetic field vectors of electromagnetic waves rotate in a circular pattern in the direction of wave propagation, which has implications for understanding magnetic fields in star formation regions.

• Importance of Circular Polarization:

  • This emission type provides insights into the strength of magnetic fields surrounding protostars and is an essential indicator of the magnetic dynamics at play during the star-formation process.
  • The measured magnetic fields near IRAS 18162-2048 are approximately 100 times stronger than Earth's.

• Challenges in Observation:

  • Observations of massive protostars are inherently difficult due to their faint emissions and the chaotic environments filled with dense gas and dust.
  • Previous observations of magnetic fields were common in low-mass protostars but much more elusive for massive protostars until this breakthrough.

• Research Collaboration: The observations were conducted using the National Radio Astronomy Observatory's Karl G. Jansky Very Large Array (VLA) in the United States, demonstrating the importance of international collaboration in astrophysics.

• Implications of Findings:

  • The retrieved data contribute to a long-standing hypothesis linking the ejection of powerful jets from stars and black holes to magnetic field dynamics, providing a clearer picture of massive star formation.
  • The findings emphasize the rarity and complexity of detecting circular polarization even in relatively more studied cosmic structures such as active galactic nuclei.

The study marks a significant advancement in astrophysics, allowing scientists to better comprehend the factors influencing the birth and early evolution of massive stars and their associated phenomena.

Conclusion: The detection of circular polarization associated with protostar IRAS 18162-2048 offers new insights into stellar formation and the role of magnetic fields in the universe, demonstrating the potential for future research in understanding similar celestial phenomena.

Publication Date: July 17, 2025.