SONS: The JCMT legacy survey of debris discs in the submillimetre

Abstract

Debris discs are evidence of the ongoing destructive collisions between planetesimals, and their presence around stars also suggests that planets exist in these systems. In this paper, we present submillimetre images of the thermal emission from debris discs that formed the SCUBA-2 Observations of Nearby Stars (SONS) survey, one of seven legacy surveys undertaken on the James Clerk Maxwell telescope between 2012 and 2015. The overall results of the survey are presented in the form of 850 µm (and 450 µm, where possible) images and fluxes for the observed fields. Excess thermal emission, over that expected from the stellar photosphere, is detected around 49 stars out of the 100 observed fields. The discs are characterised in terms of their flux density, size (radial distribution of the dust) and derived dust properties from their spectral energy distributions. The results show discs over a range of sizes, typically 1-10 times the diameter of the Edgeworth-Kuiper Belt in our Solar System. The mass of a disc, for particles up to a few millimetres in size, is uniquely obtainable with submillimetre observations and this quantity is presented as a function of the host stars' age, showing a tentative decline in mass with age. Having doubled the number of imaged discs at submillimetre wavelengths from ground-based, single dish telescope observations, one of the key legacy products from the SONS survey is to provide a comprehensive target list to observe at high angular resolution using submillimetre/millimetre interferometers (e.g., ALMA, SMA).

Debris disks around stars in the NIKA2 era

“…The North-West extension of the source HR8977 in Fig. 1 is also present in the SCUBA2 image at 850µm and ascribed to a background galaxy [10].…”

“…The three stars HD107146, Vega and HR8799 were selected because their disks offered the largest flux densities at 2mm predicted in extrapolating from the SCUBA2 data in [10]. Observations of these three stars were conducted on October 29 and 30 2017 at the IRAM 30m radiotelescope at Pico de Veleta in Spain in fair weather conditions (τ 225GHz = 0.2 − 0.30) using the new NIKA2 camera with its three arrays paved with Kinetic Inductance Detectors (KIDs) enclosed in a cryogenic system [11][12][13].…”

“…The SONS JCMT/SCUBA2 Legacy survey detected 48 debris disks in the submillimeter domain (λ = 450µm and 850µm) and found a large range of spectral slopes with β ∈ [0 − 2.7] (S ν ∝ λ −(2+β) ) [9,10], which correspond to an index q d possibly larger than 2 for the collisional cascade, i.e. size distribution steeper than the standard self similar collisinal model.…”

“…size distribution steeper than the standard self similar collisinal model. However, with a sample of a dozen of debris disks observed by SMA and ALMA at 1.3mm and 850µm, another group has found the range q d ∈ [1.61 − 1.88] [4], leading to an opposite (1) ALMA see [16] ; (2) SONS see [10] ; (*) based on grey body fit of β and λ 0 in [10].…”

HD 104860 and HD 192758: Two Debris Disks Newly Imaged in Scattered Light with the Hubble Space Telescope

“…About a hundred debris disks have been spatially resolved to date, mostly in thermal emission at 70-160μm with the Herschel Space Observatory (e.g., Booth et al 2013;Eiroa et al 2013;Matthews et al 2014;Morales et al 2016;Vican et al 2016) or at submillimeter/millimeter wavelengths with JCMT (Holland et al 2017) and ALMA (e.g., MacGregor et al 2013, 2016aSu et al 2017). Using the measured radii of a sample of Herschel-resolved disks, Pawellek et al (2014) interestingly showed that the typical grain size in these disks does not directly scale with the radiative pressure blowout particle size, but decreases with stellar luminosity.…”