Summary: ROTATIONAL MODULATION OF THE RADIO EMISSION
FROM THE M9 DWARF TVLM 513-46546: BROADBAND
COHERENT EMISSION AT THE SUBSTELLAR BOUNDARY?
G. Hallinan1
, A. Antonova2
, J.G. Doyle2
, S. Bourke1
, W. F. Brisken3
and A. Golden1
ABSTRACT
The Very Large Array was used to observe the ultracool rapidly rotating
M9 dwarf TVLM 513-46546 simultaneously at 4.88 GHz and 8.44 GHz. The
radio emission was determined to be persistent, variable and periodic at both
frequencies with a period of 2 hours. This periodicity is in excellent agreement
with the estimated period of rotation of the dwarf based on its v sin i of 60 km
s-1
. This rotational modulation places strong constraints on the source size of
the radio emitting region and hence the brightness temperature of the associated
emission. We find the resulting high brightness temperature, together with the
inherent directivity of the rotationally modulated component of the emission,

Source: Armagh Observatory

Collections: Physics