The new observations of GQ Lup (red diamond) move us toward a discovery space of smaller disks. DSHARP disks are marked with green circles. Size-luminosity relationship for millimeter continuum sources with disk properties. This means that small disks may have the same opportunity as large disks to form young planets. Long and collaborators’ observations of the GQ Lup system suggest that pebble-sized dust grains can be trapped by variations in pressure in the disk, halting the grains’ drift and giving them a chance to clump. What do these substructures tell us? One challenge to planet formation theories is that larger dust grains should migrate inward through the disk in a process called radial drift, accreting onto the star before they can clump together to form planetesimals. The high angular resolution of ALMA’s observations allow the team to resolve the dust emission even in this small disk, revealing a wealth of substructures very similar to those spotted in larger disks. In a new study led by Deryl Long (University of Michigan), a team of scientists has used ALMA to explore one of these more typical systems: a compact disk with effective radius of 19 au around the star GQ Lup A. The scale bar at the lower right indicates 5 au. Do these more typical disks show the same wealth of substructures that we’ve spotted in larger disks? And what can this tell us about planet formation?ĪLMA continuum image of the GQ Lup disk. As an example, the Disk Substructures at High Angular Resolution Project (DSHARP) survey used ALMA to image twenty large, bright disks with effective radii - the radius that encompasses 68% of the light from the dusty disk - of ~50 au on average.īut the vast majority of disks are faint, and their dusty disks are much more compact, with effective radii of less than 20 au. Thus far, however, we’ve mostly focused on imaging the especially large disks that give us the best look at disk substructure. Since then, again and again, ALMA has produced remarkable images of gaps, rings, and spiral arms in disks, all of which hint at how planets might be forming. When ALMA revealed early observations of the disks of gas and dust around young stars, we were stunned by the exquisitely detailed look this interferometer provided into newborn solar systems. The scale bars in the lower right of each image indicate 10 au. Gallery of 240 GHz (1.25 mm) continuum emission images for the disks in the DSHARP sample.
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