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SUMMARY:Eccentricities and Stellar Obliquities in Hot and Warm Jupiter Sys
 tems with External Perturbers - Kassandra Anderson (Cornell University)
DTSTART:20181015T130000Z
DTEND:20181015T140000Z
UID:TALK109594@talks.cam.ac.uk
CONTACT:Dr William Béthune
DESCRIPTION:Hot Jupiters (HJs) and warm Jupiters (WJs) exhibit several obs
 ervational puzzles\, including stellar spin-orbit misalignments (obliquiti
 es) in many HJ systems\, and substantial eccentricities in many WJ systems
 .  This talk considers the role of an external planetary companion in gene
 rating such eccentricities and stellar obliquities. In Part I of the talk\
 , we investigate whether an external companion may induce secular eccentri
 city oscillations in WJ systems\, through an apsidal precession resonance 
 (when the companion is eccentric and co-planar)\, or Lidov-Kozai oscillati
 ons (when the companion is sufficiently inclined).  We consider the sample
  of WJs with detected outer companions\, and for each system\, identify th
 e range of mutual inclinations needed to generate the observed WJ eccentri
 city. For most systems\, we find that high inclinations are needed so that
  Lidov-Kozai cycles are induced\; the outer companions are typically not  
 eccentric enough to generate the observed WJ eccentricity in a low-inclina
 tion configuration.  Observational constraints on mutual inclinations in t
 wo-planet systems are needed to clarify the role of external companions in
  secularly exciting WJ eccentricities.  In Part II of the talk\, we consid
 er the possibility of an inclined companion in exciting the stellar obliqu
 ity due to a secular resonance\, occurring when the precession rate of the
  stellar spin axis (driven by the inner planet) becomes comparable to the 
 nodal precession rate of the inner planet (driven by the outer planet).  D
 ue to their close proximity to the host star\, HJs have strongly-coupled s
 tellar spin and orbital axes\, and a strong perturber is required to raise
  the obliquity\, located within 1-2 AU. In contrast\, WJ systems experienc
 e weaker spin-orbit coupling\, and obliquity excitation may be achieved fo
 r more distant perturbers\, located at tens of AU. Unlike HJs\, WJ stellar
  obliquities have not been extensively probed.  We predict WJs may have si
 gnificant obliquities due to resonant excitation\, especially those orbiti
 ng cool host stars.
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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