Grand Design Spiral Arms in the Compact, Embedded Protoplanetary Disk of Haro 6-13

Grand Design Spiral Arms in the Compact, Embedded Protoplanetary Disk of Haro 6-13
Jane Huang, Masataka Aizawa, Jaehan Bae, Sean M. Andrews, Myriam Benisty, Edwin A. Bergin, Stefano Facchini, Christian Ginski, Michael K"uffmeier
arXiv:2506.06433v1 Announce Type: new
Abstract: Millimeter continuum spiral arms have so far only been detected in a handful of protoplanetary disks, and thus we have a limited understanding of the circumstances in which they can form. In particular, substructures in small disks ($Rlessapprox 50$ au) have not been well-characterized in comparison with large disks. We present ALMA 1.3 mm continuum observations of the disk around the T Tauri star Haro 6-13 at a resolution of $sim0.04”$ ($sim5$ au). A pair of low-contrast spiral arms are detected at disk radii from $sim10-35$ au. They can be approximated as Archimedean spirals with pitch angles ranging from $sim10-30^circ$. The low value of the disk-averaged spectral index between 1.3 and 3 mm ($alpha=2.1$) and the high brightness temperatures suggest that the millimeter continuum is likely optically thick and thus may hide sufficient mass for the disk to become gravitationally unstable and form spiral arms. CO observations have shown that Haro 6-13 is surrounded by an envelope, raising the possibility that infall is facilitating spiral arm formation.arXiv:2506.06433v1 Announce Type: new
Abstract: Millimeter continuum spiral arms have so far only been detected in a handful of protoplanetary disks, and thus we have a limited understanding of the circumstances in which they can form. In particular, substructures in small disks ($Rlessapprox 50$ au) have not been well-characterized in comparison with large disks. We present ALMA 1.3 mm continuum observations of the disk around the T Tauri star Haro 6-13 at a resolution of $sim0.04”$ ($sim5$ au). A pair of low-contrast spiral arms are detected at disk radii from $sim10-35$ au. They can be approximated as Archimedean spirals with pitch angles ranging from $sim10-30^circ$. The low value of the disk-averaged spectral index between 1.3 and 3 mm ($alpha=2.1$) and the high brightness temperatures suggest that the millimeter continuum is likely optically thick and thus may hide sufficient mass for the disk to become gravitationally unstable and form spiral arms. CO observations have shown that Haro 6-13 is surrounded by an envelope, raising the possibility that infall is facilitating spiral arm formation.