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J/A+A/611/A66       AR Sco VLA radio observations               (Stanway+, 2018)

VLA radio observations of AR Scorpii. Stanway E.R., Marsh T.R., Chote P., Gaensicke B.T., Steeghs D., Wheatley P.J. <Astron. Astrophys. 611, A66 (2018)> =2018A&A...611A..66S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf ; Stars, variable ; Polarization Keywords: white dwarfs - stars: variables: general - stars: individual: AR Scorpii - polarization Abstract: AR Scorpii is unique amongst known white dwarf binaries in showing powerful pulsations extending to radio frequencies. Here we aim to investigate the multi-frequency radio emission of AR Sco in detail, in order to constrain its origin and emission mechanisms. We present interferometric radio frequency imaging of AR Sco at 1.5, 5 and 9GHz, analysing the total flux and polarization behaviour of this source at high time resolution (10, 3 and 3s), across a full 3.6h orbital period in each band. We find strong modulation of the radio flux on the orbital period and the orbital sideband of the white dwarf's spin period (also known as the "beat" period). This indicates that, like the optical flux, the radio flux arises predominantly from on or near the inner surface of the M-dwarf companion star. The beat-phase pulsations of AR Sco decrease in strength with decreasing frequency. They are strongest at 9GHz and at an orbital phase ∼0.5. Unlike the optical emission from this source, radio emission from AR Sco shows weak linear polarization but very strong circular polarization, reaching ∼30% at an orbital phase ∼0.8. We infer the probable existence of a non-relativistic cyclotron emission component, which dominates at low radio frequencies. Given the required magnetic fields, this also likely arises from on or near the M-dwarf. Description: Time series VLA radio observations were undertaken of the highly variable white dwarf binary AR Scorpii. These were analysed for periodicity, spectral behaviour and other characteristics. Here we present time series data in the Stokes I parameter at three frequencies. These were centred at 1.5GHz (1GHz bandwidth), 5GHz (2GHz bandwidth) and 9GHz (2GHz bandwidth). The AR Sco binary is unresolved at these frequencies. In the case of the 1.5GHz data, fluxes have been deconvolved with those of a neighbouring object. Objects: ---------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------- 16 21 47.29 -22 53 10.4 AR Sco = V* AR Sco ---------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 34 1608 1.5GHz time series data table2.dat 34 3861 5GHz time series data table3.dat 34 3717 9GHz time series data
Byte-by-byte Description of file: table1.dat table2.dat table3.dat
Bytes Format Units Label Explanations
1- 16 F16.10 d RJD Reduced Julian Date (JD-2400000) 18- 24 F7.4 mJy Flux Stokes I flux 29- 34 F6.4 mJy e_Flux Uncertainty on Stokes I flux
Acknowledgements: Elisabeth Stanway, e.r.stanway(at)
(End) Patricia Vannier [CDS] 02-Feb-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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