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Astronomy & Astrophysics manuscript no. preprint c ESO 2007 July 6, 2007
 

Summary: Astronomy & Astrophysics manuscript no. preprint c ESO 2007
July 6, 2007
LETTER TO THE EDITOR
Sporadic Long-term Variability in Radio Activity from a Brown
Dwarf
A. Antonova1, J.G. Doyle1, G. Hallinan2, A. Golden2 and C. Koen3
1
Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
2
Computational Astrophysics Laboratory, I.T. Building, National University of Ireland, Galway, Ireland
3
Department of Statistics, University of the Western Cape, Private Bag X17, Bellville, 7535 Cape, South Africa
ABSTRACT
Context. Radio activity has been observed in a large variety of stellar objects, including in the last few years, ultra-cool dwarfs.
Aims. To explore the extent of long-term radio activity in ultra-cool dwarfs.
Methods. We use data taken over an extended period of 9 hr from the Very Large Array of the source 2MASS J05233822-1403022
in September 2006, plus data taken in 2004.
Results. The observation taken in September 2006 failed to detect any radio activity at 8.46 GHz. A closer inspection of earlier data
reveals that the source varied from a null detection on 3 May 2004, to 95 µJy on 17 May 2004, to 230 µJy on 18 June 2004. The
lack of detection in September 2006 suggests at least a factor of ten flux variability at 8.46 GHz. Three short photometric runs did not

  

Source: Armagh Observatory

 

Collections: Physics