A search for trends in spatially resolved debris discs at far-infrared wavelengths

Abstract

Debris discs around main-sequence stars are belts of planetesimals – asteroids and comets – formed in the protoplanetary discs around young stars. Planetesimals comprise both the building blocks of planets around young stars and the source of dusty debris around older stars. Imaging observations of dust continuum emission and scattered light reveal the location of these planetesimal belts around their host stars. Analysis of debris discs observed at millimetre wavelengths revealed a trend between the discs’ radii and the host star luminosities. This trend was tentatively linked to the preferential formation of dust-producing planetesimals near snow lines (specifically CO) in the protoplanetary discs around the host stars. Here, we perform a homogeneous analysis of 95 debris discs observed at far-infrared wavelengths by the Herschel Space Observatory and fit the obtained distribution of radii and widths as a function of stellar luminosity with a power-law relation. We identify a trend in disc radius as a function of stellar luminosity similar to that identified at millimetre wavelengths, but cannot convincingly recover it from the available data set due to the large uncertainties on disc radius and width inherent in the marginally spatially resolved data, and the bias of smaller discs around more distant stars (which are also the more luminous) being omitted from our analysis. We see a trend in disc temperature as a function of stellar luminosity, consistent with previous findings from similar analyses.

High-resolution ALMA and HST images of q1 Eri: an asymmetric debris disc with an eccentric Jupiter

“…Despite being broad, q 1 Eri's peak emission radius in the sub-mm is in accordance with the population of 26 SMA (Sub-Millimetre Array) and ALMA resolved discs in Matrà et al (2018), which (for * ∼1.59 ) predicts a sub-mm disc radius 0 =73±12 au (i.e., within 1 of our measurement). Further, this sub-mm resolved radius is entirely consistent with the archival far-IR Herschel radius of disc =81.1 +1.8 −1.3 au (Marshall et al 2020). Whilst our measurement of the disc width is however narrower than the broad Δ disc =71.1 +1.9 −13.3 au value found by Marshall et al (2020), this is likely due to the different manner in which we assess the width (i.e., we note that the extent of the disc is much broader than the ∼43 au width we define from the half-maximum emission).…”

“…Further, this sub-mm resolved radius is entirely consistent with the archival far-IR Herschel radius of disc =81.1 +1.8 −1.3 au (Marshall et al 2020). Whilst our measurement of the disc width is however narrower than the broad Δ disc =71.1 +1.9 −13.3 au value found by Marshall et al (2020), this is likely due to the different manner in which we assess the width (i.e., we note that the extent of the disc is much broader than the ∼43 au width we define from the half-maximum emission). Further, the width measurements of Marshall et al (2020) are also likely unresolved, which for example, may also be influenced by emission from an inner warm component that we discuss further in §5.3.…”

“…These studies showed the disc to be highly inclined ( >60 • ) to the plane of the sky (Stapelfeldt et al 2007;Liseau et al 2008Liseau et al , 2010 with emission concentrated at around ∼100 au, although only weak constraints could be placed on the disc's inner edge based on the ∼4 (∼70 au) resolution of Herschel, and given the HST coronagraph obscuration inside ∼50 au. More recent analysis with this Herschel data has demonstrated that the disc likely has a radius of disc =81.1 +1.8 −1.3 au, and a broad radial width of Δ disc =71.1 +1.9 −13.3 au (Marshall et al 2020). The HST data confirms the disc to be asymmetric, with this more extended in the NE than the SW.…”

High resolution ALMA and HST images of q$^1$ Eri: an asymmetric debris disc with an eccentric Jupiter

“…These studies showed the disc to be highly inclined (𝑖>60 • ) to the plane of the sky (Stapelfeldt et al 2007;Liseau et al 2008Liseau et al , 2010 with emission concentrated at around ∼100 au, although only weak constraints could be placed on the disc's inner edge based on the ∼4 (∼70 au) resolution of Herschel, and given the HST coronagraph obscuration inside ∼50 au. More recent analysis with this Herschel data has demonstrated that the disc likely has a radius of 𝑅 disc =81.1 +1.8 −1.3 au, and a broad radial width of Δ𝑅 disc =71.1 +1.9 −13.3 au (Marshall et al 2020). The HST data confirms the disc to be asymmetric, with this more extended in the NE than the SW.…”

Four new planetesimals around typical and pre-main-sequence stars (PLATYPUS) debris discs at 8.8 mm

“…HD 48370 is a G8 V star (Torres et al 2008) at a distance of 36.07±0.07 pc (Gaia Collaboration et al 2018) and has an estimated age of ∼20-50 Myr (Torres et al 2008). A peak radius for the disc to be at ∼90 au using spatially resolved Herschel images (Moór et al 2016;Marshall et al 2021). Using archival 1.3 mm ALMA observations (Project ID: 2016.2.00200S) of HD 48370, we fit a simple Gaussian to the observatory-calibrated visibilities and derive an integrated flux of 5.0 ± 0.5 mJy.…”