Home / Science / Scientific and Research Projects 2012–2014 / Radio Emission at the Bottom of the Main Sequence and a New Class of Radio Sources. Characteristics of the Magnetic Activity of Low-mass Stars and Ultracool Dwarfs

Research area:   Physical Sciences – Astronomy and Astrophysics
Research unit:   Department of Astronomy, Faculty of Physics
Funding institution:   National Science Fund, Bulgaria
Project duration:   December 2010 – June 2014
Project leader:   Assoc. Prof. Dr. Antoaneta Antonova

Antoaneta Antonova received her MSc in Astronomy from the Department of Astronomy, Sofi a University, in 2000, and her PhD – from the Armagh Observatory and Queen’s University Belfast, Northern Ireland (2008).

Since 2013, she is an Associate Professor at the Department of Astronomy, Sofi a University.

Her research Interests are in the fi eld of the stellar radio as-tronomy, cool stars and brown dwarfs.


The most unexpected manifestation of magnetic activity in ultra cool dwarfs (UCDs) has been the detection radio emission, particularly the periodic 100% circularly polarized pulses. These objects comprise a whole new class of radio sources. The pulses are produced at the poles of a large-scale magnetic field by the electron cyclotron maser (ECM) instability, the same mechanism known to be responsible for the radio emission from the magnetized planets in our solar system and certain classes of solar and stellar bursts.

The project aims to further the understanding of magnetic activity of stellar objects at the bot-tom of the main sequence and beyond. To this end, we have planned detailed studies of the generation and mechanism of radio emission, magnetic field diagnostics, the efficiency with which magnetic fields are generated, rotation rates, dependency of activity on rotation, etc.



  • 21 scientific papers published in international astronomical Journals (total IF above 88);
  • 8 papers published in the Bulgarian Astronomical Journal;
  • 9 talks and posters presented at national and international astronomical conferences;
  • Project results are included in one BSc and two MSc theses.



Artist representation of aurora from an ultra cool dwarf is shown in the left panel, periodic pulsation in the radio emission of TVLM 513-46546 detected with the VLA (2007, ApJ, 663, 25) is shown in the middle panel, while a dynamic spectrum of individual pulsations, detected with Arecibo (2009, AIPC, 1094, 146) are shown in the right panel.



Assoc. Prof. Antoaneta Antonova

Department of Astronomy, Faculty of Physics

Sofia University “St. Kliment Ohridski”

5 James Bourchier Blvd., 1164 Sofia

Phone: +359 (2) 8662324

e-mail: tony@phys.uni-sofia.bg