Name: Barnali Das
Affiliation: University of Delaware
Conference ID : ASI2022_149
Title : Coherent radio emission from hot magnetic stars
Authors : Barnali Das
Abstract Type: Oral
Abstract Category : Thesis
Abstract : Hot magnetic stars are main-sequence stars of spectral types O, B or A, that harbor kilogauss strength large-scale surface magnetic field. Coherent radio emission observed from these stars is a much more powerful cousin of the earth’s auroral kilometric radiation, produced by the electron cyclotron maser emission mechanism. The essential ingredients for such emission are the magnetic field and energetic electrons. Despite being able to provide all the necessary ingredients, the production of coherent radio emission by hot magnetic stars had been deemed extremely rare due to the small number of such stars discovered over more than decade. Through my PhD project, we set out to solve this puzzle via conducting a dedicated search for this emission at sub-GHz frequencies (an unexplored phase-space for hot magnetic stars at the time in this context). We ended up discovering eleven such stars (~73% of the currently known population) leading to the conclusion that this phenomenon is not rare at all. Besides, our observations covering an ultra-wide frequency range (0.4-4.0 GHz), supplemented by numerical simulations, showed that the coherent radio emission is greatly affected by the stellar magnetosphere, and hence carries a vast amount of information regarding the magnetospheric plasma, especially regarding events that are confined to small spatial scales. All these results have revolutionized this field, and gave recognition to the potential of coherent radio emission for becoming a unique probe for hot stars’ magnetospheres.