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Secular oscillations and Kozai cycles in planetary systems

Wallenius, Joel LU (2014) In Lund Observatory Examensarbeten ASTM31 20141
Lund Observatory
Department of Astronomy and Theoretical Physics
Abstract
The origin of the class of exoplanets typically referred to as hot Jupiters is to this day an unsettled matter. Some of the proposed formation channels predict certain values of the spin-orbit misalignment parameter, i.e. the angle between the stellar rotation axis, and the angular momentum vector of the planet orbit. One such formation channel is tidal capture following Kozai resonance (TCKR). This channel produces high misalignment, with some preference for angles around 39 deg and 141 deg. For single-planet systems, this channel is viable, but whether it functions in multi-planet systems or not is not yet clear.

This thesis primarily explores, by means of N-body simulations, what impact the secular oscillations between planets in... (More)
The origin of the class of exoplanets typically referred to as hot Jupiters is to this day an unsettled matter. Some of the proposed formation channels predict certain values of the spin-orbit misalignment parameter, i.e. the angle between the stellar rotation axis, and the angular momentum vector of the planet orbit. One such formation channel is tidal capture following Kozai resonance (TCKR). This channel produces high misalignment, with some preference for angles around 39 deg and 141 deg. For single-planet systems, this channel is viable, but whether it functions in multi-planet systems or not is not yet clear.

This thesis primarily explores, by means of N-body simulations, what impact the secular oscillations between planets in multiplanetary systems have on TCKR. Secondarily, there is some investigation into if the outermost planets in multiplanetary systems can act as low-mass Kozai companions.

The primary results include that secular oscillations do in fact interact with the Kozai effect: for every multiplanetary system there appears to be a critical combination of the Kozai companion's orbit size and inclination beyond which the effect shuts down. Because of this, secular oscillations are generally detrimental to TCKR and the production of hot Jupiters. Lastly, it would appear that planetary Kozai companions are dysfunctional if their masses are roughly equal to or smaller than those of the system's inferior planets. (Less)
Popular Abstract (Swedish)
Idag vet man att det finns planeter även utanför vårt solsystem, de snurrar runt sina stjärnor precis som vi snurrar runt Solen - vår stjärna. Man kallar dem `exoplaneter', och hittills har man detekterat över tusen stycken. En del av alla dessa exoplaneter har till synes underliga egenskaper: Deras omloppsbanor är väldigt små, endast några hundradelar av Jordens omloppsbana, samtidigt som de är väldigt stora, i nivå med Saturnus och Jupiter. Att de är så nära sina stjärnor innebär att de mottar väldiga mängder värmande strålning, och således brukar de kallas 'hot Jupiters'. En del av dem befinner sig på omloppsbanor som lutar väldigt mycket relativt deras stjärnors rotationsaxlar.

Dessa 'hot Jupiters' är problematiska av minst två... (More)
Idag vet man att det finns planeter även utanför vårt solsystem, de snurrar runt sina stjärnor precis som vi snurrar runt Solen - vår stjärna. Man kallar dem `exoplaneter', och hittills har man detekterat över tusen stycken. En del av alla dessa exoplaneter har till synes underliga egenskaper: Deras omloppsbanor är väldigt små, endast några hundradelar av Jordens omloppsbana, samtidigt som de är väldigt stora, i nivå med Saturnus och Jupiter. Att de är så nära sina stjärnor innebär att de mottar väldiga mängder värmande strålning, och således brukar de kallas 'hot Jupiters'. En del av dem befinner sig på omloppsbanor som lutar väldigt mycket relativt deras stjärnors rotationsaxlar.

Dessa 'hot Jupiters' är problematiska av minst två skäl. För det första borde inte massiva planeter ha små omloppsbanor, och för det andra borde inte omloppsbanorna luta. En möjlig lösning på dessa problem är den så kallade Kozaieffekten, som när den kombineras med tidvattenskrafter och dynamik i stjärnhopar, kan transportera en Jupiterliknande planet från en stor omloppsbana till en liten och lutande omloppsbana.

I den här uppsatsen undersöks huruvida en sådan process är möjlig. Resultaten tyder på att den är det, men att den inte på egna ben kan vara förklaring till samtliga detekterade 'hot Jupiters'. (Less)
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author
Wallenius, Joel LU
supervisor
organization
course
ASTM31 20141
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Kozai effect, Kozai mechanism, secular oscillations, hot Jupiters, planets, planetary systems
publication/series
Lund Observatory Examensarbeten
report number
2014-EXA90
language
English
id
4646291
date added to LUP
2014-09-22 10:14:44
date last changed
2014-09-22 10:14:44
@misc{4646291,
  abstract     = {The origin of the class of exoplanets typically referred to as hot Jupiters is to this day an unsettled matter. Some of the proposed formation channels predict certain values of the spin-orbit misalignment parameter, i.e. the angle between the stellar rotation axis, and the angular momentum vector of the planet orbit. One such formation channel is tidal capture following Kozai resonance (TCKR). This channel produces high misalignment, with some preference for angles around 39 deg and 141 deg. For single-planet systems, this channel is viable, but whether it functions in multi-planet systems or not is not yet clear.

This thesis primarily explores, by means of N-body simulations, what impact the secular oscillations between planets in multiplanetary systems have on TCKR. Secondarily, there is some investigation into if the outermost planets in multiplanetary systems can act as low-mass Kozai companions.

The primary results include that secular oscillations do in fact interact with the Kozai effect: for every multiplanetary system there appears to be a critical combination of the Kozai companion's orbit size and inclination beyond which the effect shuts down. Because of this, secular oscillations are generally detrimental to TCKR and the production of hot Jupiters. Lastly, it would appear that planetary Kozai companions are dysfunctional if their masses are roughly equal to or smaller than those of the system's inferior planets.},
  author       = {Wallenius, Joel},
  keyword      = {Kozai effect,Kozai mechanism,secular oscillations,hot Jupiters,planets,planetary systems},
  language     = {eng},
  note         = {Student Paper},
  series       = {Lund Observatory Examensarbeten},
  title        = {Secular oscillations and Kozai cycles in planetary systems},
  year         = {2014},
}