Mike Alexandersen

THE OUTER SOLAR SYSTEM ORIGINS SURVEY. I. DESIGN AND FIRST-QUARTER DISCOVERIES

National Research Council of Canada; National Science and Engineering Research Council of Canada; Academia Sinica Postdoctoral Fellowship

A Uranian Trojan and the Frequency of Temporary Giant-Planet Co-Orbitals

A Uranian Trojan Bodies that share their orbit with that of a planet and that trail or lead the planet by 60° are called Trojans. Based on data from the Canada-France-Hawaii Telescope, Alexandersen et al. (p. 994) have found an object shadowing Uranus that is predicted to remain a Trojan for at least 700,000 years and to stay in co-orbital motion for around one million years before escaping. Observations with the Canada-France-Hawaii Telescope reveal a body that temporarily shares its orbit with that of Uranus. Trojan objects share a planet’s orbit, never straying far from the triangular Lagrangian points, 60° ahead of (L4) or behind (L5) the planet. We report the detection of a Uranian Trojan; in our numerical integrations, 2011 QF99 oscillates around the Uranian L4 Lagrange point for >70,000 years and remains co-orbital for ∼1 million years before becoming a Centaur. We constructed a Centaur model, supplied from the transneptunian region, to estimate temporary co-orbital capture frequency and duration (to a factor of 2 accuracy), finding that at any time 0.4 and 2.8% of the population will be Uranian and Neptunian co-orbitals, respectively. The co-orbital fraction (∼2.4%) among Centaurs in the International Astronomical Union Minor Planet Centre database is thus as expected under transneptunian supply.

The 5:1 Neptune Resonance as Probed by CFEPS: Dynamics and Population

The Canada-France Ecliptic Plane Survey discovered four trans-Neptunian objects with semi-major axes near the 5:1 resonance, revealing a large and previously undetected intrinsic population. Three of these objects are currently resonant with Neptune, and the fourth is consistent with being an object that escaped the resonance at some point in the past. The non-resonant object may be representative of a detached population that is stable at slightly lower semi-major axes than the 5:1 resonance. We generated clones of these objects by resampling the astrometric uncertainty and examined their behavior over a 4.5 Gyr numerical simulation. The majority of the clones of the three resonant objects (>90%) spend a total of 10^7 years in resonance during their 4.5 Gyr integrations; most clones experience multiple periods of resonance capture. Our dynamical integrations reveal an exchange between the 5:1 resonance, the scattering objects, and other large semi-major axis resonances, especially the 4:1, 6:1, and 7:1. The multiple capture events and relatively short resonance lifetimes after capture suggest that these objects are captured scattering objects that stick in the 5:1 resonance. These 5:1 resonators may be representative of a temporary population, requiring regular contributions from a source population. We examined the dynamical characteristics (inclination, eccentricity, resonant island, libration amplitude) of the detected objects and their clones in order to provide an empirical model of the orbit structure of the 5:1 resonance. This resonance is dynamically hot and includes primarily symmetric librators. Given our orbit model, the intrinsic population necessary for the detection of these three objects in the 5:1 resonance is 1900(+3300 -1400, 95% confidence) with H_g 0.5.

OSSOS III - Resonant Trans-Neptunian Populations: Constraints from the first quarter of the Outer Solar System Origins Survey

NASA Solar System Workings grant [NNX15AH59G]; National Research Council of Canada; National Science and Engineering Research Council of Canada

OSSOS. II. A sharp transition in the absolute magnitude distribution of the Kuiper Belt's scattering population

We measure the absolute magnitude,

All planetesimals born near the Kuiper belt formed as binaries

H

TRIPPy: Trailed Image Photometry in Python

, distribution,

OSSOS. V. Diffusion in the Orbit of a High-perihelion Distant Solar System Object

dN(H) \propto 10^{\alpha H}

OSSOS. VI. Striking Biases in the Detection of Large Semimajor Axis Trans-Neptunian Objects

of the scattering Trans-Neptunian Objects (TNOs) as a proxy for their size-frequency distribution. We show that the H-distribution of the scattering TNOs is not consistent with a single-slope distribution, but must transition around

DISCOVERY OF TWO ADDITIONAL JOVIAN IRREGULARS

H_g \sim 9