THIRUVANANTHAPURAM: Massive protostars in our galaxy, that would later evolve to have mass of over 8-10 times that of the Sun, have remained an enigma for astrophysicists for decades.
For the first time in the world, a team of researchers at the Indian Institute of Space Science & Technology (IIST), Thiruvananthapuram, in association with international scientists, have detected and measured magnetism near an infant massive star.
The finding opens an exciting window into the understanding of how massive stars form, which later go on to shape entire galaxies. A protostar is the earliest known stage of a star that is beginning to form. The study was carried out on protostar IRAS 18162-2048, located 4,500 light years away using the National Radio Astronomy Observatory’s Karl G Jansky Very Large Array in the US.
‘The Astrophysical Journal Letters’ brought out by the American Astronomical Society has published the study in detail. The researchers detected radio emission, with a special property known as circular polarisation near IRAS 18162-2048. The emission offers the first direct clue to the strength of magnetic fields in the immediate surroundings of a forming massive star.
While strong magnetic fields have been observed earlier in low-mass protostars that go on to form stars like the Sun, measuring such fields around massive protostars has been a tough task until now. The new data allowed researchers to infer the magnetic field near the protostar to be about 20-35 Gauss, roughly 100 times stronger than Earth’s magnetic field.
‘Study proves physics behind jet formations universal’
These values match what scientists have observed in low-mass protostars, hinting at a common magnetic origin.
“The findings of the study will help us understand the process behind the formation of massive stars. Besides, the magnetic field values are now scientifically measured from near the protostar while the earlier ones were inferred based on certain models,” said Prof Sarita Vig of IIST who conceptualised the work.
The study also unearthed evidence that supports a long-standing theory that powerful jets from stars and black holes are driven by the same magnetic engine. “By detecting circular polarisation, the study provides strong evidence that the physics behind jet formation is universal across different astrophysical environments,” said Amal George Cheriyan, a PhD student at IIST, guided by Prof Sarita.
Amal and Sarita carried out the study in collaboration with Prof Nirupam Roy from the Indian Institute of Science (IISc), Bengaluru, Prof Samir Mandal of IIST and scientists from the Institute of Radio Astronomy and Astrophysics (IRyA) of the National Autonomous University of Mexico (UNAM), Mexico, and Instituto de Astronomia Teorica y Experimental (IATE) of the Universidad Nacional de Córdoba (UNC) Córdoba, Argentina.