A stellar mass dependence of structured disks: a possible link with exoplanet demographics. (arXiv:2104.06838v3 [astro-ph.EP] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Marel_N/0/1/0/all/0/1">Nienke van der Marel</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Mulders_G/0/1/0/all/0/1">Gijs Mulders</a> (2,3) ((1) University of Victoria, BC, Canada (2) Universidad Adolfo Ibanez, Chile)
Gaps in protoplanetary disks have long been hailed as signposts of planet
formation. However, a direct link between exoplanets and disks remains hard to
identify. We present a large sample study of ALMA disk surveys of nearby
star-forming regions to disentangle this connection. All disks are classified
as either structured (transition, ring, extended) or non-structured (compact)
disks. Although low-resolution observations may not identify large scale
substructure, we assume that an extended disk must contain substructure from a
dust evolution argument. A comparison across ages reveals that structured disks
retain high dust masses up to at least 10 Myr, whereas the dust mass of
compact, non-structured disks decreases over time. This can be understood if
the dust mass evolves primarily by radial drift, unless drift is prevented by
pressure bumps. We identify a stellar mass dependence of the fraction of
structured disks. We propose a scenario linking this dependence with that of
giant exoplanet occurrence rates. We show that there are enough exoplanets to
account for the observed disk structures if transitional disks are created by
exoplanets more massive than Jupiter, and ring disks by exoplanets more massive
than Neptune, under the assumption that most of those planets eventually
migrate inwards. On the other hand, the known anti-correlation between
transiting super-Earths and stellar mass implies those planets must form in the
disks without observed structure, consistent with formation through pebble
accretion in drift-dominated disks. These findings support an evolutionary
scenario where the early formation of giant planets determines the disk’s dust
evolution and its observational appearance.
Gaps in protoplanetary disks have long been hailed as signposts of planet
formation. However, a direct link between exoplanets and disks remains hard to
identify. We present a large sample study of ALMA disk surveys of nearby
star-forming regions to disentangle this connection. All disks are classified
as either structured (transition, ring, extended) or non-structured (compact)
disks. Although low-resolution observations may not identify large scale
substructure, we assume that an extended disk must contain substructure from a
dust evolution argument. A comparison across ages reveals that structured disks
retain high dust masses up to at least 10 Myr, whereas the dust mass of
compact, non-structured disks decreases over time. This can be understood if
the dust mass evolves primarily by radial drift, unless drift is prevented by
pressure bumps. We identify a stellar mass dependence of the fraction of
structured disks. We propose a scenario linking this dependence with that of
giant exoplanet occurrence rates. We show that there are enough exoplanets to
account for the observed disk structures if transitional disks are created by
exoplanets more massive than Jupiter, and ring disks by exoplanets more massive
than Neptune, under the assumption that most of those planets eventually
migrate inwards. On the other hand, the known anti-correlation between
transiting super-Earths and stellar mass implies those planets must form in the
disks without observed structure, consistent with formation through pebble
accretion in drift-dominated disks. These findings support an evolutionary
scenario where the early formation of giant planets determines the disk’s dust
evolution and its observational appearance.
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