A5024060673- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- High-pressure geophysics and materials
- Gamma-ray bursts and supernovae
- Geological and Geochemical Analysis
- Planetary Science and Exploration
- Geophysics and Gravity Measurements
- Marine and environmental studies
- Molecular Spectroscopy and Structure
- Paleontology and Stratigraphy of Fossils
- Space Exploration and Technology
- Computational Geometry and Mesh Generation
- Astronomical Observations and Instrumentation
- Plant Water Relations and Carbon Dynamics
- Geology and Paleoclimatology Research
- Mathematics and Applications
- Point processes and geometric inequalities
- Geophysics and Sensor Technology
Planetary Science Institute
2016-2024
University of California, Berkeley
2023-2024
Canadian Institute for Theoretical Astrophysics
2017-2022
University of Toronto
2017-2022
University of Cambridge
2020-2022
Cornell University
2015-2019
Pennsylvania State University
2013
Northern Arizona University
2013
Using the Keck Planet Imager and Characterizer (KPIC), we obtained high-resolution (R$\sim$35,000) $K$-band spectra of four planets orbiting HR 8799. We clearly detected \water{} CO in atmospheres 8799 c, d, e, tentatively a combination b. These are most challenging directly imaged exoplanets that have been observed at high spectral resolution to date when considering both their angular separations flux ratios. developed forward modeling framework allows us jointly fit diffracted starlight...
Abstract When orbiting hotter stars, hot Jupiters are often highly inclined relative to their host star equator planes. By contrast, cooler stars more aligned. Prior attempts explain this correlation between stellar obliquity and effective temperature have proven problematic. We show how resonance locking—the coupling of the planet's orbit a gravity mode ( g -mode)—can solve mystery. Cooler with radiative cores likely be found -mode frequencies increased substantially by core hydrogen...
It is usually thought that viscous torque works to align a circumbinary disk with the binary's orbital plane. However, recent numerical simulations suggest may evolve configuration perpendicular binary orbit ("polar alignment") if eccentric and initial disk-binary inclination sufficiently large. We carry out theoretical study on long-term evolution of inclined disks around binaries, calculating warp profile dissipative acting disk. For aspect ratio $H/r$ larger than viscosity parameter...
The CHIME/FRB collaboration recently reported the detection of a 16 day periodicity in arrival times radio bursts from FRB 180916.J0158+65. We study possibility that observed arises free precession magnetized neutron star, and put constraints on different components star's magnetic fields. Using simple geometric model, where are emitted rotating star magnetosphere, we show emission pattern as function time can match
Significance The Sun’s equator lines up with the orbits of planets. This fact supports theory that stars and their planets inherit angular momentum from same source: gravitational collapse a molecular cloud. Most astronomers expected spin-orbit alignment to be universal feature planetary systems. proved false: many drastic misalignments are known, possible reasons have been offered. In one theory, distant companion star upsets at an early stage, while is still surrounded by protoplanetary...
Recent SPH simulations by Martin et al. (2014) suggest a circumstellar gaseous disk may exhibit coherent eccentricity-inclination oscillations due to the tidal forcing of an inclined binary companion, in manner that resembles Lidov-Kozai hierarchical triple systems. We carry out linear stability analysis for eccentricity growth disks binaries, including effects gas pressure and viscosity secular (orbital-averaged) force from companion. find depends on dimensionless ratio ($S$) between...
Many hot Jupiter (HJ) systems have been observed to their stellar spin axis misaligned with the planet's orbital angular momentum axis. The origin of this spin-orbit misalignment and formation mechanism HJs remain poorly understood. A number recent works suggested that gravitational interactions between host stars, protoplanetary disks, inclined binary companions may tilt respect disk's axis, producing planetary orbits. These previous considered idealized disk evolution models neglected...
Newly formed planets (or brown dwarfs) may possess discs or rings which occupy an appreciable fraction of the planet's Hill sphere and extend beyond Laplace radius, where tidal torque from host star dominates over oblate planet. Such a disc/ring can exhibit unique, detectable transit signatures, provided that is significantly misaligned with orbital plane There exists tentative evidence for extended ring system around young K5 1 SWASP J140747−354542. We present general theoretical study...
Although tidal dissipation in binary stars has been studied for over a century, theoretical predictions have yet to match the observed properties of populations. This work quantitatively examines recent proposal circularization by resonance locking, where arises from resonances between star's natural oscillation frequencies and harmonics orbital frequency, are `locked' an extended period time due concurrent stellar evolution. We focus on with axi-symmetric gravity-modes, examine binaries...
Several recent studies have suggested that circumstellar disks in young stellar binaries may be driven into misalignement with their host stars due to secular gravitational interactions between the star, disk and binary companion. The such systems is twisted/warped torques from oblate central star external We calculate warp profile, taking account of bending wave propagation viscosity disk. show for typical protostellar parameters, small, thereby justifying "flat-disk" approximation adopted...
We present analytic calculations of the electromagnetic torques acting on a magnetic neutron star rotating in vacuum, including near-zone associated with inertia dipole and quadrupole fields. incorporate these into rotational dynamics rigid-body star, show that effects inertial torque can be understood as modification moment tensor star. apply our equation to Crab pulsar, intrinsic distortions various torques, investigate possibility counter-alignment inclination angle, suggested by recent...
Rocky planets orbiting M-dwarf stars in the habitable zone tend to be driven synchronous rotation by tidal dissipation, potentially causing difficulties for maintaining a climate on planet. However, planet may captured into asynchronous spin-orbit resonances, and this capture more likely if has sufficiently large intrinsic triaxial deformation. We derive analytic expression maximum triaxiality of rocky planet, with without liquid envelope, as function planet's radius, density, rigidity...
After the Tidal Disruption Event (TDE) of a star around SuperMassive Black Hole (SMBH), if stellar debris stream rapidly circularizes and forms compact disk, TDE emission is expected to peak in soft X-ray or far Ultra-Violet (UV). The fact that many candidates are observed near UV optical has challenged conventional models. By idealizing disk as nested sequence elliptical orbits which communicate adiabatically via pressure forces, heated by energy dissipated during circularization nearly...
Context. The population of strongly irradiated Jupiter-sized planets has no equivalent in the Solar System. It is characterised by bloated atmospheres and large atmospheric scale heights. Recent space-based observations SO 2 photochemistry have demonstrated knowledge that can be gained about Earth’s uniqueness from detailed studies these unusual planets. Aims. Here we explore atmosphere WASP-172 b, a planet similar terms temperature bloating to recently studied HD 149026 b. We characterise...
Measurements of the obliquities in exoplanet systems have revealed certain remarkable architectures, some which are very different from those seen Solar System. Nearly 200 obliquity measurements been obtained based on observations Rossiter-McLaughlin (RM) effect. Here, we report 19 planetary systems, previously led to 17 clear detections RM effect and 2 less secure detections. After adding new tally, used entire collection investigate four issues that arisen literature. Here consider...
Abstract We introduce the OATMEAL survey, an effort to measure obliquities of stars with transiting brown dwarf companions. observed a transit close-in ( P orb = 1.74 days) GPX-1 b using Keck Planet Finder spectrograph sky-projected angle between its orbital axis and spin early F-type host star λ ). measured 6.°9 ± 10.°0, suggesting orbit that is prograde well aligned stellar equator. Hot Jupiters around F are frequently found have highly misaligned orbits, polar retrograde orbits being...
We re-analyze the pristine eclipsing binary data from $\textit{Kepler}$ and TESS missions, focusing on eccentricity measurements at short orbital periods to emperically constrain tidal circularization. find an average circularization period of $~$6 days, as well a $\sim$3 days for $\textit{Kepler}$/TESS field binaries. argue previous spectroscopic surveys reported longer due small sample sizes, which were contaminated by abundance binaries with circular orbits out $\sim$10 but we re-affirm...
KH 15D contains a circumbinary disk that is tilted relative to the orbital plane of central binary. The precession and motion binary together produce rich phenomena in photometric light curve. In this work, we present discovery preliminary analysis two objects resemble key features from Zwicky Transient Facility. These new objects, Bernhard-1 Bernhard-2, show large-amplitude ($>1.5\,$mag), long-duration (more than tens days), periodic dimming events. A one-sided screen model developed...
KH 15D is a system which consists of young, eccentric binary, and circumbinary disk obscures the binary as precesses. We develop self-consistent model that provides reasonable fit to photometric variability was observed in over past 60 years. Our suggests has an inner edge $r_{\rm in}\lesssim 1 \ {\rm au}$, outer out} \sim few misaligned relative stellar by $\sim$5-16 degrees, with more inclined than edge. The difference between inclinations (warp) longitude ascending nodes (twist) at edges...
After the Tidal Disruption Event (TDE) of a star around SuperMassive Black Hole (SMBH), bound stellar debris rapidly forms an accretion disk. If disk is not aligned with spinning SMBH's equatorial plane, will be driven into Lense-Thirring precession spin axis, possibly affecting TDE's light curve. We carry out eigenmode analysis such to understand how disk's warp structure, precession, and inclination evolution are influenced by properties. find oscillatory may develop as result strong...
Abstract Close binary systems present challenges to planet formation. As separations decrease, so do the occurrence rates of protoplanetary disks in young and planets mature systems. For that retain disks, their disk masses sizes are altered by presence companion. Through study with known orbital parameters, we seek determine properties promote retention therefore In this work, characterize binary−disk system FO Tau. We first full solution for system, finding <mml:math...
Abstract Recent observations have demonstrated that some subsets of even moderately wide-separation planet-hosting binaries are preferentially configured such planetary and binary orbits appear to lie within the same plane. In this work, we explore dissipation during protoplanetary disk phase, induced by warping as system is forced into nodal recession an inclined companion a possible avenue achieving orbit–orbit alignment. We analytically model coupled evolution angular momentum vector...
Large dips in the brightness for a number of stars have been observed, which tentative explanation is occultation star by transiting circumplanetary disk or ring system. In order disk/rings to block host star's light, must be tilted out planet's orbital plane, poses stability problems due radial extent required explain dip durations. This work uses N-body integrations study structure and disk/ring systems plane spinning mass quadrupole. Simulating as collection test particles with orbits...
The 1-D evolution equations for warped discs come in two flavors: For very viscous the internal torque vector G is uniquely determined by local conditions disc, and warps tend to damp out rapidly if they are not continuously driven. inviscid discs, on other hand, becomes a dynamic quantity, warp will propagate through disc as wave. governing both regimes usually treated separately. A unified set of was postulated recently Martin et al. (2019), but yet derived from underlying physics....