Investigating the radio emission from Investigating the radio emission from stellar and sub-stellar systems: stellar and sub-stellar systems: How common isHow common is Coherent Emission?Coherent Emission?

The TEAM:G. Umana1, O., B. Slee2, E. Budding3, A. Antonova4, D. Blank5, C. S. Buemi1, J. D. Bunton11, J.G. Doyle6, N. Erkan7, A. Golden8, G. Hallinan8, J. Lazio9, P. Leto10, G. Ramsay6, C. Trigilio1

1- INAF-Osservatorio Astrofisico di Catania-ITALY; 2-ATNF Sydney AU; 3- Carter National Observatory, Wellington, New Zeland; 4-University of Sofia, Bulgaria.; 5-James Cook University, Townsville, AU; 6- Armagh Observatory, N. Ireland; 7-Centre for Astrophysics Research, University of Canakkale, Turkey; 8- NUI Galway, Ireland; 9- Naval Reserch Laboratory, USA; 10- INAF-IRA, ITALY;11-CSIRO, AU.

Aims of the project:Aims of the project:

Survey of different classes of magnetically active stars to detect coronal microwave emission due to gyro-synchrotron or coherent plasma mechanism

A new survey of large samples would significantly enlarge the known stellar radio emitting database

Until now, targeted observations of well known radio stars have been our only approach to detailing their properties

Expected Science outcomes:Expected Science outcomes:

Multi-epoch observations to pick up serendipitous flaring activity and thus find more typical characteristics, from statistical studies of a larger source population.

Comparison of such data with manifestations of activity, across a wide range of wavelengths, can provide vital information on stellar magnetic activity and related effects.

Coherent emission can probe fundamental parameters of stellar magnetospheres (field intensity and topology and electron energy distribution)

Behaviour of stellar radio emission:Behaviour of stellar radio emission:

Stellar radio emission is highly variable, showing two different regimes: quiescent periods (slowly varying flux density, up to several

mJy); and active periods (series of strong outburst events that may last

from minutes to several days and reach flux densities up to ~1Jy). Both quiescent and flaring emissions related to magnetic activity

(gyro-synchrotron emission).

Narrow-band, radio bursts, possessing very high circular polarization (up to 100%) and fine temporal structure of 10–50 ms. This coherent emission, (TB up to 1016 K), has been detected from RS CVn’s, dwarf flare stars, chemically peculiar stars, ultracompact binaries and brown dwarfs. Such bursts are often superimposed on a quiescent emission.

Source Identification Source Identification (Non high time resolution)(Non high time resolution)

Use Continuum imaging point source list (EMU) and match with known stellar position gives primary targets.

Use 5 second continuum image point source data to Identify possible active period on stars

◦ increase in flux and spectral index Identify possible bursts

◦ Narrow band emission

Match active period and burst detection against primary targets◦ Definite detection

Match active period and burst detection against stellar positions◦ Probable detection

Other active period and burst detections against ◦ Possible detection

High time resolution High time resolution

Request Tied array beam for targets, including status◦ Definite target – would hope for very high probability of tied array

beam being allocated◦ Possible target – beam allocated with low priority

Integrate power in tied array beam 1MHz bands, 1ms time resolution

◦ Data 300 bands, 1000 sample/s 2 pol 6bytes/sample = 3.6 Mbytes/beam

◦ 0-10 beams at any one time, average about one◦ Data preferably to Geraldton for storage and later analysis◦ Estimate 2 TB per week

Observing mode: comemsual◦ Expect approximately uniform distribution on sky