Hints of a Population of Solar System Analog Planets from ALMA

TL;DR

This study analyzes a compact protoplanetary disk around GQ Lup A using ALMA data, revealing substructures similar to larger disks, which suggests planet formation processes are common even in smaller disks, hinting at solar system analogs.

Contribution

It demonstrates that small, compact disks can host substructures indicative of planet formation, expanding understanding beyond large, bright disks.

Findings

Detection of a gap at ~10 au in GQ Lup A's disk

Similar substructures found in small disks as in larger DSHARP disks

Evidence supporting planet formation at Saturnian distances

Abstract

The recent ALMA DSHARP survey provided illuminating results on the diversity of substructures in planet forming disks. These substructures trace pebble-sized grains accumulated at local pressure maxima, possibly due to planet-disk interactions or other planet formation processes. DSHARP sources are heavily biased to large and massive disks that only represent the high (dust flux) tail end of the disk population. Thus it is unclear whether similar substructures and corresponding physical processes also occur in the majority of disks which are fainter and more compact. Here we explore the presence and characteristics of features in a compact disk around GQ Lup A, the effective radius of which is 1.5 to 10 times smaller than those of DSHARP disks. We present our analysis of ALMA 1.3mm continuum observations of the GQ Lup system. By fitting visibility profiles of the continuum emission, we find substructures including a gap at ~ 10 au. The compact disk around GQ Lup exhibits similar substructures to those in the DSHARP sample, suggesting that mechanisms of trapping pebble-sized grains are at work in small disks as well. Characteristics of the feature at ~ 10 au, if due to a hidden planet, are evidence of planet formation at Saturnian distances. Our results hint at a rich world of substructures to be identified within the common population of compact disks, and subsequently a population of solar system analogs within these disks. Such study is critical to understanding the formation mechanisms and planet populations in the majority of protoplanetary disks.