Radio Monitoring of Protoplanetary Discs

Abstract

Protoplanetary disc systems observed at radio wavelengths often show excess emission above that expected from a simple extrapolation of thermal dust emission observed at short millimetre wavelengths. Monitoring the emission at radio wavelengths can be used to help disentangle the physical mechanisms responsible for this excess, including free-free emission from a wind or jet, and chromospheric emission associated with stellar activity. We present new results from a radio monitoring survey conducted with Australia Telescope Compact Array over the course of several years with observation intervals spanning days, months and years, where the flux variability of 11 T Tauri stars in the Chamaeleon and Lupus star forming regions was measured at 7 and 15 mm and 3 and 6 cm. Results show that for most sources are variable to some degree at 7 mm, indicating the presence of emission mechanisms other than thermal dust in some sources. Additionally, evidence of grain growth to cm-sized pebbles was found for some sources that also have signs of variable flux at 7 mm. We conclude that multiple processes contributing to the emission are common in T Tauri stars at 7 mm and beyond, and that a detection at a single epoch at radio wavelengths should not be used to determine all processes contributing to the emission.

Accepted 2017 January 4, Monthly Notices of the Royal Astronomical Society

References in corpus (5)

• A Submillimeter View of Circumstellar Dust Disks in $\rho$ Ophiuchus
• Investigating grain growth in disks around southern T Tauri stars at millimetre wavelengths
• Large grains in disks around young stars: ATCA observations of WW Cha, RU Lup, and CS Cha
• Astrometric and photometric monitoring of GQ Lup and its sub-stellar companion
• The Herschel view of circumstellar discs: a multi-wavelength study of Chamaeleon I

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• A Study of Millimeter Variability in FUor Objects
• Probing Inner-Edge of Dead Zones in Protoplanetary Disks with ALMA and Next Generation Very Large Array
• Gas kinematics of key prebiotic molecules in GV Tau N revealed with an ALMA, PdBI, and Herschel synergy
• Large Dust Grains and a Possible Dust Trap in the Polar Circumbinary Disc of HD 98800B
• Characterization of the dust content in the ring around Sz 91: indications for planetesimal formation?