7 research outputs found
On the Migratory Behavior of Planetary Systems
For centuries, an orderly view of planetary system architectures dominated the discourse on planetary systems. However, there is growing evidence that many planetary systems underwent a period of upheaval, during which giant planets "migrated" from where they formed. This thesis addresses a question key to understanding how planetary systems evolve: is planetary migration typically a smooth, disk-driven process or a violent process involving strong multi-body gravitational interactions? First, we analyze evidence from the dynamical structure of debris disks dynamically sculpted during planets' migration. Based on the orbital properties our own solar system's Kuiper belt, we deduce that Neptune likely underwent both planet-planet scattering and smooth migration caused by interactions with leftover planetesimals. In another planetary system, Beta Pictoris, we find that the giant planet discovered there must be responsible for the observed warp of the system's debris belt, reconciling observations that suggested otherwise. Second, we develop two new approaches for characterizing planetary orbits: one for distinguishing the signal of a planet's orbit from aliases, spurious signals caused by gaps in the time sampling of the data, and another to measure the eccentricity of a planet's orbit from transit photometry, "the photoeccentric effect." We use the photoeccentric effect to determine whether any of the giant planets discovered by the Kepler Mission are currently undergoing planetary migration on highly elliptical orbits. We find a lack of such "super-eccentric" Jupiters, allowing us to place an upper limit on the fraction of hot Jupiters created by the stellar binary Kozai mechanism. Finally, we find new correlations between the orbital properties of planets and the metallicity of their host stars. Planets orbiting metal-rich stars show signatures of strong planet-planet gravitational interactions, while those orbiting metal-poor stars do not. Taken together, the results of thesis suggest that suggest that both disk migration and planet-planet interactions likely play a role in setting the architectures of planetary systems.Astronom
The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
We present a statistical analysis of the first 300 stars observed by the
Gemini Planet Imager Exoplanet Survey (GPIES). This subsample includes six
detected planets and three brown dwarfs; from these detections and our contrast
curves we infer the underlying distributions of substellar companions with
respect to their mass, semi-major axis, and host stellar mass. We uncover a
strong correlation between planet occurrence rate and host star mass, with
stars M 1.5 more likely to host planets with masses between 2-13
M and semi-major axes of 3-100 au at 99.92% confidence. We fit a
double power-law model in planet mass (m) and semi-major axis (a) for planet
populations around high-mass stars (M 1.5M) of the form , finding = -2.4 0.8 and
= -2.0 0.5, and an integrated occurrence rate of %
between 5-13 M and 10-100 au. A significantly lower occurrence rate
is obtained for brown dwarfs around all stars, with 0.8% of
stars hosting a brown dwarf companion between 13-80 M and 10-100
au. Brown dwarfs also appear to be distributed differently in mass and
semi-major axis compared to giant planets; whereas giant planets follow a
bottom-heavy mass distribution and favor smaller semi-major axes, brown dwarfs
exhibit just the opposite behaviors. Comparing to studies of short-period giant
planets from the RV method, our results are consistent with a peak in
occurrence of giant planets between ~1-10 au. We discuss how these trends,
including the preference of giant planets for high-mass host stars, point to
formation of giant planets by core/pebble accretion, and formation of brown
dwarfs by gravitational instability.Comment: 52 pages, 18 figures. AJ in pres
The Gemini Planet Imager Exoplanet Survey : giant planet and brown dwarf demographics from 10 to 100 au
We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey. This subsample includes six detected planets and three brown dwarfs; from these detections and our contrast curves we infer the underlying distributions of substellar companions with respect to their mass, semimajor axis, and host stellar mass. We uncover a strong correlation between planet occurrence rate and host star mass, with stars M* > 1.5 Mâ more likely to host planets with masses between 2 and 13MJup and semimajor axes of 3â100 au at 99.92% confidence. We fit a double power-law model in planet mass (m) and semimajor axis (a) for planet populations around high-mass stars (M* > 1.5 Mâ) of the form d2N/(dm da) â mα aÎČ, finding α = â2.4 ± 0.8 and ÎČ = â2.0 ± 0.5, and an integrated occurrence rate of 9+5-4% between 5â13MJup and 10â100 au. A significantly lower occurrence rate is obtained for brown dwarfs around all stars, with 0.8+0.8-0.5% of stars hosting a brown dwarf companion between 13â80MJup and 10â100 au. Brown dwarfs also appear to be distributed differently in mass and semimajor axis compared to giant planets; whereas giant planets follow a bottom-heavy mass distribution and favor smaller semimajor axes, brown dwarfs exhibit just the opposite behaviors. Comparing to studies of short-period giant planets from the radial velocity method, our results are consistent with a peak in occurrence of giant planets between âŒ1 and 10 au. We discuss how these trends, including the preference of giant planets for high-mass host stars, point to formation of giant planets by core/pebble accretion, and formation of brown dwarfs by gravitational instability.Peer reviewe
OSSOS: constraints on resonant trans-Neptunian populations from the full survey sample
International audienceThe Outer Solar System Origins Survey (OSSOS) has discovered more than 300 objects in mean motion resonances with Neptune, including more than 100 objects in Neptuneâs 3:2 resonance. This quadruples the available characterized sample of resonant trans-Neptunian objects. This sample can be used to test models of the current populations of these resonances and the distributions of objects within them, which will provide valuable constraints on the dynamical history of Neptune. We will report on the distribution of objects within the 3:2 resonant population and provide updated constraints on their H magnitude and eccentricity distribution. We will provide an updated estimate of the intrinsic population ratios between Neptuneâs resonances based on the full OSSOS sample, highlight interesting constraints for individual resonant populations, and report new discoveries in resonances not previously known to be occupied
OSSOS: constraints on resonant trans-Neptunian populations from the full survey sample
International audienceThe Outer Solar System Origins Survey (OSSOS) has discovered more than 300 objects in mean motion resonances with Neptune, including more than 100 objects in Neptuneâs 3:2 resonance. This quadruples the available characterized sample of resonant trans-Neptunian objects. This sample can be used to test models of the current populations of these resonances and the distributions of objects within them, which will provide valuable constraints on the dynamical history of Neptune. We will report on the distribution of objects within the 3:2 resonant population and provide updated constraints on their H magnitude and eccentricity distribution. We will provide an updated estimate of the intrinsic population ratios between Neptuneâs resonances based on the full OSSOS sample, highlight interesting constraints for individual resonant populations, and report new discoveries in resonances not previously known to be occupied
The Gemini Planet Imager Exoplanet Survey:giant planet and brown dwarf demographics from 10 to 100 au
We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey. This subsample includes six detected planets and three brown dwarfs; from these detections and our contrast curves we infer the underlying distributions of substellar companions with respect to their mass, semimajor axis, and host stellar mass. We uncover a strong correlation between planet occurrence rate and host star mass, with stars M* > 1.5 Mâ more likely to host planets with masses between 2 and 13MJup and semimajor axes of 3â100 au at 99.92% confidence. We fit a double power-law model in planet mass (m) and semimajor axis (a) for planet populations around high-mass stars (M* > 1.5 Mâ) of the form d2N/(dm da) â mα aÎČ, finding α = â2.4 ± 0.8 and ÎČ = â2.0 ± 0.5, and an integrated occurrence rate of 9+5-4% between 5â13MJup and 10â100 au. A significantly lower occurrence rate is obtained for brown dwarfs around all stars, with 0.8+0.8-0.5% of stars hosting a brown dwarf companion between 13â80MJup and 10â100 au. Brown dwarfs also appear to be distributed differently in mass and semimajor axis compared to giant planets; whereas giant planets follow a bottom-heavy mass distribution and favor smaller semimajor axes, brown dwarfs exhibit just the opposite behaviors. Comparing to studies of short-period giant planets from the radial velocity method, our results are consistent with a peak in occurrence of giant planets between âŒ1 and 10 au. We discuss how these trends, including the preference of giant planets for high-mass host stars, point to formation of giant planets by core/pebble accretion, and formation of brown dwarfs by gravitational instability