A5004354935- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Space Exploration and Technology
- Geophysics and Sensor Technology
- Molecular Spectroscopy and Structure
- Adaptive optics and wavefront sensing
- Modeling, Simulation, and Optimization
- Planetary Science and Exploration
- Geophysics and Gravity Measurements
- Astronomical and nuclear sciences
- Galaxies: Formation, Evolution, Phenomena
- Computational Physics and Python Applications
- Atomic and Subatomic Physics Research
- Radio Astronomy Observations and Technology
- Spacecraft and Cryogenic Technologies
- Advanced Thermodynamic Systems and Engines
- Magnetic confinement fusion research
- Quantum, superfluid, helium dynamics
- Astronomical Observations and Instrumentation
Millennium Institute of Astrophysics
2021-2024
Indiana University Bloomington
2024
Pontificia Universidad Católica de Chile
2010-2023
University of Arizona
2020-2021
The Scarborough Hospital
2016-2020
University of Toronto
2016-2020
Canadian Institute for Theoretical Astrophysics
2016-2020
Kavli Institute for Particle Astrophysics and Cosmology
2017
Princeton University
2011-2016
Princeton Public Schools
2011
We study the steady-state orbital distributions of giant planets migrating through combination Kozai-Lidov (KL) mechanism due to a stellar companion and friction tides raised on planet by host star. run large set Monte Carlo simulations that describe secular evolution star-planet-star triple system including effects from general relativistic precession, planetary spin evolution, tides. Our show KL migration produces Hot Jupiters (HJs) with semi-major axes are generally smaller than in...
Most warm Jupiters (gas-giant planets with $0.1~{\rm AU}\lesssim a \lesssim1$ AU) have pericenter distances that are too large for significant orbital migration by tidal friction. We study the possibility undergoing secular eccentricity oscillations excited an outer companion (a planet or star) in eccentric and/or mutually inclined orbit. In this model migrate periodically, high-eccentricity phase of oscillation when distance is small, but typically observed at much lower eccentricities....
Many exoplanets in close-in orbits are observed to have relatively high eccentricities and large stellar obliquities. We explore the possibility that these result from planet–planet scattering by studying dynamical outcomes a number of orbit integrations systems with two three gas-giant planets (0.05 AU < 0.15 AU). find at orbital separations, unstable starting low mutual inclinations (e ≲ 0.1, i 0.1) generally lead collisions which collision product is planet on low-eccentricity,...
We constrain the intrinsic architecture of Kepler planetary systems by modeling observed multiplicities transiting planets (tranets) and their transit timing variations (TTVs). robustly determine that fraction Sun-like stars with Kepler-like planets, $\eta_{\rm Kepler}$, is $30\pm3\%$. Here are have radii $R_{\rm p} \gtrsim R_\oplus$ orbital periods $P<400$~days. Our result thus significantly revises previous claims more than 50\% such planets. Combining average number per star ($\sim0.9$),...
Abstract The Milky Way and a significant fraction of galaxies are observed to host central massive black hole (MBH) embedded in non-spherical nuclear star cluster. We study the secular orbital evolution compact-object binaries these environments characterize excitation extremely large eccentricities that can lead mergers by gravitational radiation. find eccentricity occurs most efficiently when nodal precession timescale binary’s orbit around MBH due cluster becomes comparable (within factor...
Abstract The warm Neptune GJ 3470b transits a nearby ( d = 29 pc) bright slowly rotating M1.5-dwarf star. Using spectroscopic observations during two with the newly commissioned NEID spectrometer on WIYN 3.5 m Telescope at Kitt Peak Observatory, we model classical Rossiter–McLaughlin effect, yielding sky-projected obliquity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>λ</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>98</mml:mn>...
The multiple-planet systems discovered by the Kepler mission exhibit following feature: planet pairs near first-order mean-motion resonances prefer orbits just outside nominal resonance, while avoiding those inside resonance. We explore an extremely simple dynamical model for formation, in which planets grow mass at a prescribed rate without orbital migration or dissipation. develop analytic version of this two-planet two limiting cases: grows quickly slowly relative to characteristic...
We study the possibility that hot Jupiters are formed through secular gravitational interactions between two planets in eccentric orbits with relatively low mutual inclinations ($\lesssim20^\circ$) and friction due to tides raised on planet by host star. term this migration mechanism Coplanar High-eccentricity Migration because, like disk migration, it allows for occur same plane which formed. can operate from following typical initial configurations: (i) inner a circular orbit outer an...
The hundreds of multiple planetary systems discovered by the \textit{Kepler} mission are typically observed to reside in close-in ($\lesssim0.5$ AU), low-eccentricity, and low-inclination orbits. We run N-body experiments study effect that unstable outer ($\gtrsim1$ AU) giant planets, whose end orbital configurations resemble those Radial Velocity population, have on these super-Earth systems. Our show planets greatly reduce multiplicity inner super-Earths surviving population can large...
The binary black hole mergers detected by Advanced LIGO/Virgo have shown no evidence of large spins. However, because best measures the effective combination two spins along orbital angular momentum ($\chi_{\rm eff}$), it is difficult to distinguish between binaries with slowly-spinning holes and lying in plane. Here, we study spin dynamics for a distant companion. For initially aligned binary, find that $\chi_{\rm eff}$ "freezes" near zero as orbit decays through emission gravitational...
Binaries within the sphere of influence a massive black hole (MBH) in galactic nuclei are susceptible to Lidov-Kozai (LK) mechanism, which can drive orbits high eccentricities and trigger strong interactions binary such as emission gravitational waves (GWs), mergers compact objects. These events potential sources for GW detectors Advanced LIGO VIRGO. The LK mechanism is only effective if highly inclined with respect its orbit around MBH (within few degrees 90 deg), implying low rates....
Abstract We report the discovery of a transiting planet first identified as candidate in Sector 1 Transiting Exoplanet Survey Satellite ( TESS ), and then confirmed with precision radial velocities. HD 1397b has mass <?CDATA ${M}_{{\rm{P}}}\,={0.367}_{-0.023}^{+0.022}\,{M}_{{\rm{J}}}$?> , radius ${R}_{{\rm{P}}}={1.023}_{-0.013}^{+0.013}\,{R}_{{\rm{J}}}$?> orbits its bright host star V = 7.8 mag) an orbital period $11.5366\pm 0.0003$?> d on moderately eccentric orbit...
We study the dynamical stability and fates of hierarchical (in semi-major axis) two-planet systems with arbitrary eccentricities mutual inclinations. run a large number long-term numerical integrations use Support Vector Machine algorithm to search for an empirical boundary that best separates stable from experiencing either ejections or collisions star. propose following new criterion stability: $a_{\rm out}(1-e_{\rm out})/[a_{\rm in}(1+e_{\rm in})]>2.4\left[\max(\mu_{\rm in},\mu_{\rm...
Abstract TRAPPIST-1 is a late M-dwarf orbited by seven Earth-sized planets with orbital period ratios near chain of mean motion resonances. Due to uncertain system parameters, most configurations drawn from the inferred posterior distribution are unstable on short timescales ∼0.5 Myr, even when including eccentricity damping effect tides. By contrast, we show that physically plausible resonant generated through disk migration stable without tidal dissipation at least 50 Myr (10 10 orbits),...
ABSTRACT The presence of a planetary system can shield planetesimal disk from the secular gravitational perturbations due to distant outer massive objects (planets or stellar companions). As host star evolves off main sequence become white dwarf, these planets be engulfed during giant phase, triggering instabilities and leading tidal disruptions small rocky bodies. These disrupted bodies feed dwarfs with material possibly explain high-metallicity in their atmospheres. We illustrate how this...
Abstract Warm Jupiters lay out an excellent laboratory for testing models of planet formation and migration. Their separation from the host star makes tidal reprocessing their orbits ineffective, which preserves orbital architectures that result planet-forming process. Among measurable properties, inclination with respect to stellar rotational axis, stands as a crucial diagnostic understanding migration mechanisms behind origin close-in planets. Observational limitations have made...
ABSTRACT The requirement that planetary systems be dynamically stable is often used to vet new discoveries or set limits on unconstrained masses orbital elements. This typically carried out via computationally expensive N -body simulations. We show characterizing the complicated and multi-dimensional stability boundary of tightly packed amenable machine-learning methods. find training an XGBoost algorithm physically motivated features yields accurate classifier in systems. On timescale...
The Jovian-sized object WD~1856~b transits a white dwarf (WD) in compact $1.4$-day orbit. Unlikely to have endured stellar evolution its current orbit, is thought migrated from much wider separations. Because the WD old, and member of well-characterized hierarchical multiple, well-known Kozai mechanism provides an effective migration channel for WD~1856~b. Moreover, lack tides star allows us directly connect semi-major axis pre-migration one, which we can infer initial conditions system. By...
Abstract High-eccentricity tidal migration predicts the existence of highly eccentric proto hot Jupiters on “tidal circularization track,” meaning that they might eventually become Jupiters, but their migratory journey remains incomplete. Having experienced moderate amounts evolution orbital elements, Jupiter systems can be powerful test beds for underlying mechanisms eccentricity growth. Notably, may used discriminating between variants high-eccentricity migration, each predicting a...
Planetary migration models predict multiple planets captured into a chain of mean-motion resonances during the disk phase. Over dozen systems have been observed in these configurations, with nearly all close-in lack resonant chains for orbital periods longer than ∼300 days. Dynamical studies often overlook fact that stars do not evolve isolation. In this work, we explore possibility absence giant long-period may be due to post-formation disruption caused by stellar flybys. For 2:1-2:1 and...
Abstract Over 100 rocky planets orbiting Sun-like stars in very short orbital periods (≲1 day) have been discovered by the Kepler mission. The origin of these planets, known as ultra-short-period (USP) remains elusive. Here, we propose that most originally at ∼5–10 days, reach their current orbits via high-eccentricity migration. In a scaled-down version dynamics may experienced high-mass analogs, hot Jupiters, high eccentricities chaotic secular interactions with companion and then undergo...
Despite decades of effort, the mechanisms by which spin axis a star and orbital axes its planets become misaligned remain elusive. Particularly, it is great interest whether large spin-orbit misalignments observed are driven primarily high-eccentricity migration -- expected to have occurred for short-period, isolated or reflect more universal process that operates across systems with variety present-day architectures. Compact multi-planet offer unique opportunity differentiate between these...
Abstract Despite decades of effort, the mechanisms by which spin axis a star and orbital axes its planets become misaligned remain elusive. In particular, it is great interest whether large spin–orbit misalignments observed are driven primarily high-eccentricity migration—expected to have occurred for short-period, isolated planets—or reflect more universal process that operates across systems with variety present-day architectures. Compact multiplanet offer unique opportunity differentiate...