| Name: Sarita Vig |
| Affiliation: Indian Institute of Space Science and Technology |
| Conference ID: ASI2026_8 |
| Title: The Unique Case of IRAS 18162-2048: A massive protostar driving the largest scale jet in our Galaxy |
| Abstract Type: Oral |
| Abstract Category: Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Author(s) and Co-Author(s) with Affiliation: Sarita Vig(IIST, Trivandrum), Amal G. Cherian(IIST, Trivandrum) |
| Abstract: Our knowledge of massive protostars is limited compared to our understanding of their low-mass counterparts. IRAS 18162-2048, a massive protostar located at a distance of 1.4 kpc drives the largest known protostellar jet in our Galaxy, extending upto several parsecs. This presentation will highlight radio observations of the massive protostar and the jet through continuum and polarisation observations. Non-thermal emission has been observed from multiple lobes of the jet based on spectral index measurements using low frequency radio continuum observations from uGMRT at 325, 610 and 1280 MHz. Towards the massive protostar, we detect radio continuum circular polarization (CP) for the first time using observations carried out with the Karl G. Jansky Very Large Array. The observed fractional CP is found to be in the range 3% - 5% across frequencies between 4 and 6 GHz. No linear polarisation (LP) is detected towards the protostar. We examine several possible origins for the presence of CP and lack of LP. We identify two likely mechanisms: (i) gyrosynchrotron emission and (ii) Faraday conversion caused by turbulence in a magnetized medium, both involving mildly relativistic electrons. From these observations, we derive the first estimate of the magnetic field strength near a massive protostar, B≳20–35 G. This magnetic field measurement provides valuable constraints on theoretical models of massive star formation. The magnetic field estimate obtained towards IRAS 18162 suggests that it is a likely precursor to a magnetic massive star. |
