Dust unveils the formation of a mini-Neptune planet in a protoplanetary ring. (arXiv:1902.05143v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Perez_S/0/1/0/all/0/1">Sebastián Pérez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Casassus_S/0/1/0/all/0/1">Simon Casassus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baruteau_C/0/1/0/all/0/1">Clément Baruteau</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dong_R/0/1/0/all/0/1">Ruobing Dong</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hales_A/0/1/0/all/0/1">Antonio Hales</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cieza_L/0/1/0/all/0/1">Lucas Cieza</a>
Rings and radial gaps are ubiquitous in protoplanetary disks. Their possible
connection to planet formation is currently subject to intense debate. In
principle, giant planet formation leads to wide gaps which separate the gas and
dust mass reservoir in the outer disk, while lower mass planets lead to shallow
gaps which are manifested mainly on the dust component. We used the Atacama
Large Millimeter/submillimeter Array (ALMA) to observe the star HD 169142, host
to a prominent disk with deep wide gaps that sever the disk into inner and
outer regions. Here we report that the outer ring of the HD 169142 disk is
itself a compact system of three fine and eccentric rings. The mass reservoir
beyond a deep gap can thus host ring systems. The observed rings are narrow in
radial extent (width/radius of 1.5/57.3, 1.8/64.2 and 3.4/76.0, all in au) and
have asymmetric mutual separations: the first and middle ring are separated by
7 au while the middle and outermost ring are distanced by 12 au. Using
hydrodynamical modeling we found that a simple explanation, involving a single
migrating low mass planet (10 M$_oplus$), entirely counts for such an
apparently complex phenomenon. Inward migration of the planet naturally
explains the ring’s asymmetric mutual separation. The isolation of HD 169142’s
outer rings thus allows a proof of concept to interpret the detailed
architecture of the outer region of protoplanetary disks with low mass planet
formation of mini-Neptune’s size, i.e. as in the protosolar nebula.
Rings and radial gaps are ubiquitous in protoplanetary disks. Their possible
connection to planet formation is currently subject to intense debate. In
principle, giant planet formation leads to wide gaps which separate the gas and
dust mass reservoir in the outer disk, while lower mass planets lead to shallow
gaps which are manifested mainly on the dust component. We used the Atacama
Large Millimeter/submillimeter Array (ALMA) to observe the star HD 169142, host
to a prominent disk with deep wide gaps that sever the disk into inner and
outer regions. Here we report that the outer ring of the HD 169142 disk is
itself a compact system of three fine and eccentric rings. The mass reservoir
beyond a deep gap can thus host ring systems. The observed rings are narrow in
radial extent (width/radius of 1.5/57.3, 1.8/64.2 and 3.4/76.0, all in au) and
have asymmetric mutual separations: the first and middle ring are separated by
7 au while the middle and outermost ring are distanced by 12 au. Using
hydrodynamical modeling we found that a simple explanation, involving a single
migrating low mass planet (10 M$_oplus$), entirely counts for such an
apparently complex phenomenon. Inward migration of the planet naturally
explains the ring’s asymmetric mutual separation. The isolation of HD 169142’s
outer rings thus allows a proof of concept to interpret the detailed
architecture of the outer region of protoplanetary disks with low mass planet
formation of mini-Neptune’s size, i.e. as in the protosolar nebula.
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