Giant Planet Migration, Disk Evolution, and the Origin of Transitional Disks

Abstract

We present models of giant planet migration in evolving protoplanetary disks. Our disks evolve subject to viscous transport of angular momentum and photoevaporation, while planets undergo Type II migration. We use a Monte Carlo approach, running large numbers of models with a range in initial conditions. We find that relatively simple models can reproduce both the observed radial distribution of extrasolar giant planets, and the lifetimes and accretion histories of protoplanetary disks. The use of state-of-the-art photoevaporation models results in a degree of coupling between planet formation and disk clearing, which has not been found previously. Some accretion across planetary orbits is necessary if planets are to survive at radii 1.5 AU, and if planets of Jupiter mass or greater are to survive in our models they must be able to form at late times, when the disk surface density in the formation region is low. Our model forms two different types of "transitional" disks, embedded planets and clearing disks, which show markedly different properties. We find that the observable properties of these systems are broadly consistent with current observations, and highlight useful observational diagnostics. We predict that young transition disks are more likely to contain embedded giant planets, while older transition disks are more likely to be undergoing disk clearing.

Circumstellar disks and planets

“…As it drains, the inner disk becomes optically thin to EUV photons, which increases the wind rate by a factor of ∼ 10, and the wind then clears the disk from the inside-out in ∼ 10 5 yr (Alexander et al, 2006a,b). This rapid clearing after a long lifetime appears to be consistent with observations of disk evolution (Alexander et al, 2006b;Alexander and Armitage, 2009), and due to the role of the wind in precipitating disk clearing, this class of models are often referred to as "UV-switch" models (Clarke et al, 2001).…”

“…These objects are rare, accounting for 10% of the TT population, and this relative lack of objects between the CTT & WTT states has long been interpreted as evidence that the transition from disk-bearing to disk-less is rapid, occurring on a time scale 1-2 orders of magnitude shorter than the Myr disk lifetime (Skrutskie et al, 1990;Kenyon and Hartmann, 1995;Simon and Prato, 1995;Wolk and Walter, 1996). In recent years, it has become clear that the transitional disks are not a homologous class of objects (Salyk et al, 2009), and a number of different mechanisms have been proposed for their origin (Najita et al, 2007;Chiang and Murray-Clay, 2007;Ireland and Kraus, 2008;Alexander, 2008a;Cieza et al, 2008;Alexander and Armitage, 2009). It is clear, however, that transitional disks have undergone significant evolution, and further investigation of them may be crucial to our understanding of disk evolution and clearing.…”

The low-mass stellar population in the young cluster Tr 37

“…Various physical processes can be invoked for disk removal, including grain growth, photoevaporation, and planet formation. In addition, other external parameters may also contribute to define the path followed by a dispersing disk, such as age, stellar mass, stellar and planetary companions, initial conditions, cluster environment, crowdedness in the star-forming region, and angular momentum of the collapsing core (Hartmann et al 2006;Bouwman et al 2006;Alexander & Armitage 2009;Fang et al 2013a;Sicilia-Aguilar et al 2013;Dullemond et al 2006). Further processes (ejection in multiple systems, photo-erosion of cores by massive nearby stars; Bate et al 2005Bate et al , 2012Whitworth & Zinnecker 2004) may also play a role in the formation of lowmass systems.…”

The long-term evolution of photoevaporating transition discs with giant planets

“…At a time tcreation we assume that a planet forms in the disc with an initial mass of Mp = 0.7Mjup. Similar to many other works found in the literature that studied the long term disc evolution or planet disc interaction (e.g., Nelson et al 2000;Armitage et al 2002;Alexander & Armitage 2009;Zhu et al 2011), we do not model the formation of the planet itself. The simulated radial extent of the disc is [0.1rp, 10rp], where rp is the planet orbital radius.…”

“…While considerable theoretical effort has been invested in understanding what process may be responsible for the creation of a transition disc, relatively little has been done to understand their time evolution (but see for example Alexander & Armitage 2009, although the holes there are much smaller, and . In this work we will just assume that a planet is a sufficient condition to produce a transition disc, and we explore what happens when such a system is allowed to evolve.…”