scholarly journals Kozai–Lidov oscillations triggered by a tilt instability of detached circumplanetary discs

2021 ◽  
Vol 502 (3) ◽  
pp. 4426-4434
Author(s):  
Rebecca G Martin ◽  
Zhaohuan Zhu ◽  
Philip J Armitage ◽  
Chao-Chin Yang ◽  
Hans Baehr

ABSTRACT Circumplanetary discs can be linearly unstable to the growth of disc tilt in the tidal potential of the star–planet system. We use 3D hydrodynamical simulations to characterize the disc conditions needed for instability, together with its long-term evolution. Tilt growth occurs for disc aspect ratios, evaluated near the disc outer edge, of H/r ≳ 0.05, with a weak dependence on viscosity in the wave-like regime of warp propagation. Lower mass giant planets are more likely to have circumplanetary discs that satisfy the conditions for instability. We show that the tilt instability can excite the inclination to above the threshold where the circumplanetary disc becomes unstable to Kozai–Lidov (KL) oscillations. Dissipation in the KL unstable regime caps further tilt growth, but the disc experiences large oscillations in both inclination and eccentricity. Planetary accretion occurs in episodic accretion events. We discuss implications of the joint tilt–KL instability for the detectability of circumplanetary discs, for the obliquity evolution of forming giant planets, and for the formation of satellite systems.

2015 ◽  
Vol 454 (2) ◽  
pp. 2173-2182 ◽  
Author(s):  
Giovanni P. Rosotti ◽  
Barbara Ercolano ◽  
James E. Owen

2012 ◽  
Vol 8 (S293) ◽  
pp. 356-361
Author(s):  
Shang-Fei Liu ◽  
James Guillochon ◽  
Douglas N. C. Lin ◽  
Enrico Ramirez-Ruiz

AbstractRecent observations have revealed several Jupiter-mass planets with highly eccentric and / or misaligned orbits, which clearly suggests that dynamical processes operated in these systems. These dynamical processes may result in close encounters between Jupiter-like planets and their host stars. Using three-dimensional hydrodynamical simulations, we find that planets with cores are more likely to be retained by their host stars in contrast with previous studies which suggested that coreless planets are often ejected. We propose that after a long term evolution some gas giant planets could be transformed into super-Earths or Neptune-like planets, which is supported by our adiabatic evolution models. Finally, we analyze the orbits and structure of known planets and Kepler candidates and find that our model is capable of producing some of the shortest-period objects.


2016 ◽  
Vol 04 (07) ◽  
pp. 172-174
Author(s):  
Kruchenitsky Gregory Mikhailovich ◽  
Statnikov Konstantin Andreevich ◽  
Zakharov Vladimir Matveevich

2015 ◽  
Vol 11 (A29A) ◽  
pp. 19-26
Author(s):  
Hubert Klahr ◽  
Aiara Lobo Gomes

AbstractWe run global two dimensional hydrodynamical simulations, using the PLUTO code and the planet-disk model of Uribe et al. 2011, to investigate the effect of the convective overstability (CO) on planet-disk interactions. First, we study the long-term evolution of planet-induced vortices. We found that the CO leads to smoother planetary gap edges, thus weaker planet-induced vortices. The main result was the observation of two generation of vortices, which can pose an explanation for the location of the vortex in the Oph IRS48 system. The lifetime of the primary vortices, as well as the birth time of the secondary vortices are shown to be highly dependent on the thermal relaxation timescale. Second, we study the long-term evolution of the migration of low mass planets and assess whether the CO can prevent the saturation of the horseshoe drag. We found that the disk parameters that favour slow inward or outward migration oppose the amplification of vortices, meaning that the CO does not seem to be a good mechanism to prevent the saturation of the horseshoe drag. On the other hand, we observed a planetary trap, caused by vortices formed in the horseshoe region. This trap may be an alternative mechanism to prevent the fast type I migration rates.


Author(s):  
Chaithra. H. U ◽  
Vani H.R

Now a days in Wireless Local Area Networks (WLANs) used in different fields because its well-suited simulator and higher flexibility. The concept of WLAN  with  advanced 5th Generation technologies, related to a Internet-of-Thing (IOT). In this project, representing the Network Simulator (NS-2) used linked-level simulators for Wireless Local Area Networks and still utilized IEEE 802.11g/n/ac with advanced IEEE 802.11ah/af technology. Realization of the whole Wireless Local Area Networking linked-level simulators inspired by the recognized Vienna Long Term Evolution- simulators. As a outcome, this is achieved to link together that simulator to detailed performances of Wireless Local Area Networking with Long Term Evolution, operated in the similar RF bands. From the advanced 5th Generation support cellular networking, such explore is main because different coexistences scenario can arise linking wireless communicating system to the ISM and UHF bands.


2013 ◽  
Vol 8 (15) ◽  
pp. 33-40
Author(s):  
Javier Enrique Arévalo Peña

En la planeación de las próximas generaciones de redes inalámbricas es importante contar con estudios de radio propagación que permitan establecer diseños adecuados para ofrecer los servicios proyectados por las nuevas tecnologías a los usuarios móviles. En este artículo se presentan aspectos relacionados con el comportamiento de cobertura de radio propagación del modelo propuesto por el 3GPP (3rd Generation Partnership Project) para un entorno urbano en una red LTE (Long Term Evolution) empleando sistemas de antenas convencionales y sistemas de antena adaptativas (AAS). Para ello se utiliza la herramienta de software ICS Designer y se establece como escenario los alrededores la Fundación Universidad Autónoma de Colombia ubicada en el centro urbano de la ciudad de Bogotá D. C.


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