A5054602195- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Molecular Spectroscopy and Structure
- Planetary Science and Exploration
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- SAS software applications and methods
- Adaptive optics and wavefront sensing
- Space Exploration and Technology
- Spaceflight effects on biology
- Phase Equilibria and Thermodynamics
- Italy: Economic History and Contemporary Issues
University of California, Berkeley
2017-2025
Planetary Science Institute
2020-2025
Heidelberg University
2021-2024
University of Michigan
2018-2019
We use a semi-analytic model for globular cluster (GC) formation built on dark matter merger trees to explore the relative role of physics and hierarchical assembly in determining properties GC populations. Many previous works have argued that observed linear relation between total mass halo points fundamental -- connection or indicates GCs formed at very high redshift before feedback processes introduced nonlinearity baryon-to-dark relation. demonstrate $M_{\rm vir}(z=0) \gtrsim 10^{11.5}...
Globular cluster (GC) systems around galaxies of a vast mass range show remarkably simple scaling relations. The combined all GCs is constant fraction the total galaxy and mean metallicity dispersion GC system scale up weakly with mass. massive, metal-poor ('blue') clusters increases mass, while that metal-rich ('red') does not. A significant age–metallicity relation emerges from analysis resolved stellar populations in Galactic unresolved nearby galaxies. Remarkably, these trends can be...
Abstract Many dozens of circumstellar discs show signatures sculpting by planets. To help find these protoplanets direct imaging, we compute their broadband spectral energy distributions, which overlap with the JWST (James Webb Space Telescope) and ALMA (Atacama Large Millimeter Array) passbands. We consider how circumplanetary spherical envelopes are heated accretion irradiation. Searches JWST’s NIRCam (Near-Infrared Camera) blue portion MIRI (Mid-Infrared Instrument) most promising since...
We present BVRI and unfiltered light curves of 93 Type Ia supernovae (SNe Ia) from the Lick Observatory Supernova Search (LOSS) follow-up program conducted between 2005 2018. Our sample consists 78 spectroscopically normal SNe Ia, with remainder divided distinct subclasses (three SN 1991bg-like, three 1991T-like, four Iax, two peculiar, super-Chandrasekhar events), has a median redshift 0.0192. The in our have coverage 16 photometric epochs at cadence 5.4 days, first observed epoch is ~4.6...
ABSTRACT Globular cluster (GC) systems demonstrate tight scaling relations with the properties of their host galaxies. In previous work, we developed an analytic model for GC formation in a cosmological context that matches nearly all these observed relations. Here, apply our to investigate detail physical origins and evolution The ratio combined mass GCs MGC dark matter halo Mh is constant at redshifts, but its normalization evolves by factor ∼10 from birth z = 0. relation steeper than...
Abstract Multiple planets undergoing disk migration may be captured into a chain of mean-motion resonances with the innermost planet parked near disk’s inner edge. Subsequent dynamical evolution disrupt these resonances, leading to nonresonant configurations typically observed among Kepler that are Gyr old. In this scenario, resonant expected more common in younger systems. This prediction can now tested, thanks recent discoveries young planets, particular those stellar clusters, by NASA’s...
The hunt is on for dozens of protoplanets hypothesised to reside in protoplanetary discs with imaged gaps. How bright these planets are, and what they will grow become, depend their accretion rates, which may be the runaway regime. Using 3D global simulations we calculate maximum gas rates planet masses $M_{\rm p}$ from 1$\,M_{\oplus}$ $10\,M_{\rm J}$. When small enough that its sphere influence fully embedded disc, a Bondi radius $r_{\rm Bondi}$ smaller than disc's scale height $H_{\rm --...
Abstract We explore the properties of dense star clusters that are likely to be nurseries stellar black holes pairing in close binaries. combine a cosmological model globular cluster formation with analytic prescriptions for dynamical assembly and evolution hole binaries (BHBs) constrain which types most form tight enough coalesce within Hubble time. find BHBs ejected later merge ex situ characteristic mass <?CDATA ${M}_{\mathrm{cl}}\sim {10}^{5.3}\,{M}_{\odot }$?> , whereas more massive...
Observations of young star clusters reveal that the high-mass end cluster initial mass function (CIMF) deviates from a pure power law and instead truncates exponentially. We investigate effects this truncation on formation globular (GC) systems by updating our analytic model for evolution, which is based dark matter halo merger trees coupled to empirical galactic scaling relations, has been shown in previous work match wide array observational data. The cut-off masses...
The orbital period ratios of neighbouring sub-Neptunes are distributed asymmetrically near first-order resonances. There deficits systems – 'troughs' in the ratio histogram just short commensurability, and excesses 'peaks' wide it. We reproduce quantitatively strongest peak-trough asymmetries, 3:2 2:1 resonances, using dissipative interactions between planets their natal discs. Disc eccentricity damping captures bodies into resonance clears trough, when combined with disc-driven convergent...
ABSTRACT There are excesses of sub-Neptunes just wide period commensurabilities like the 3:2 and 2:1, corresponding deficits narrow them. Any theory that explains this ratio structure must also explain strong transit timing variations (TTVs) observed near resonance. Besides an amplitude a period, sinusoidal TTV has phase. Often overlooked, phases effectively integration constants, encoding information about initial conditions or environment. Many TTVs resonance exhibit non-zero phases. This...
Abstract TESS and Kepler have revealed that practically all close-in sub-Neptunes form in mean-motion resonant chains, most of which unravel on timescales 100 Myr. Using N -body integrations, we study how planetary collisions from destabilized chains produce the orbital period distribution observed among mature systems, focusing fine structures remaining post-instability. In their natal planets near first-order resonances ratios just wide perfect commensurability, driven there by disk...
Young stellar clusters across nearly five orders of magnitude in mass appear to follow a power-law mass-radius relationship (MRR), $R_{\star} \propto M_{\star}^{\alpha}$, with $\alpha \approx 0.2 - 0.33$. We develop simple analytic model for the cluster relation. consider galaxy disc hydrostatic equilibrium, which hosts population molecular clouds that fragment into clumps undergoing formation and feedback-driven expansion. The predicts relation M_{\star}^{1/2}$ dependence on kpc-scale gas...
We present BVRI and unfiltered Clear light curves of 70 stripped-envelope supernovae (SESNe), observed between 2003 2020, from the Lick Observatory Supernova Search (LOSS) follow-up program. Our SESN sample consists 19 spectroscopically normal SNe~Ib, two peculiar SNe Ib, six SN Ibn, 14 Ic, one ten Ic-BL, 15 IIb, ambiguous IIb/Ib/c, superluminous SNe. photometry has (on a per-SN basis) mean coverage 81 photometric points (median 58 points) cadence 3.6d 1.2d). From our full sample, subset 38...
Multiple planets undergoing disk migration may be captured into a chain of mean-motion resonances with the innermost planet parked near disk's inner edge. Subsequent dynamical evolution disrupt these resonances, leading to non-resonant configurations typically observed among {\it Kepler} that are Gyrs old. In this scenario, resonant expected more common in younger systems. This prediction can now tested, thanks recent discoveries young planets, particularly those stellar clusters, by NASA's...
We simulate recoiling black hole trajectories from $z=20$ to $z=0$ in dark matter halos, quantifying how parameter choices affect escape velocities. These include the strength of dynamical friction, presence stars and gas, accelerating expansion universe (Hubble acceleration), host halo accretion motion, seed mass. $Λ$CDM increases velocities by up 0.6 dex significantly shortens return timescales compared non-accreting cases. Other parameters change orbit damping rates but have subdominant...
ABSTRACT We assess whether chondrules, once-molten mm-sized spheres filling the oldest meteorites, could have formed from super-km s−1 collisions between planetesimals in solar nebula. High-velocity release hot and dense clouds of silicate vapour which entrain heat chondrule precursors. Thermal histories CB chondrules are reproduced for colliding bodies ∼10–100 km radius. The slower cooling rates non-CB, porphyritic point to colliders with radii ≳ 500 km. How collisionally dispersed into...
Gaps imaged in protoplanetary discs are suspected to be opened by planets. We compute the present-day mass accretion rates $\dot{M}_{\rm p}$ of seven hypothesized gap-embedded planets, plus two confirmed planets PDS 70 disc. The based on disc gas surface densities $\Sigma_{\rm gas}$ from C$^{18}$O observations, and planet masses $M_{\rm simulations fitted observed gaps. Assuming is Bondi-like, we find eight out nine cases that consistent with time-averaged value given current system age,...
Many dozens of protoplanetary discs show signatures sculpting by planets. To help find these protoplanets direct imaging, we compute their broadband spectral energy distributions, which overlap with the JWST (James Webb Space Telescope) and ALMA (Atacama Large Millimeter Array) passbands. We consider circumplanetary spherical envelopes, combinations heated protoplanet accretion external irradiation. Searches JWST's NIRCam (Near-Infrared Camera) blue portion MIRI (Mid-Infrared Instrument) are...
Observations with the Transiting Exoplanet Survey Satellite and Kepler have revealed that practically all close-in sub-Neptunes form in mean-motion resonant chains, most of which unravel on timescales 100 Myr. Using a series N-body integrations, we study how planetary collisions resulting from destabilization chains produce distribution orbital periods observed among mature systems, focusing fine structures remain post-instability. In their natal planets near first-order resonances period...
Abstract We describe the implementation of a new module which can be used to simulate physical systems in motion particles is affected by stochastic forces. Such forces are expected present turbulent circumstellar disks or remnant planetesimal disks. Our offers convenient way generate correlated noise with user-specified amplitude and auto-correlation time for each particle. The has minimal memory requirements freely available within REBOUNDx additional effects library.
The hunt is on for dozens of protoplanets hypothesised to reside in protoplanetary discs with imaged gaps. How bright these planets are, and what they will grow become, depend their accretion rates, which may be the runaway regime. Using 3D global simulations we calculate maximum gas rates planet masses $M_{\rm p}$ from 1$\,M_{\oplus}$ $10\,M_{\rm J}$. When small enough that its sphere influence fully embedded disc, a Bondi radius $r_{\rm Bondi}$ smaller than disc's scale height $H_{\rm --...
There are excesses of sub-Neptunes just wide period commensurabilities like the 3:2 and 2:1, corresponding deficits narrow them. Any theory that explains this ratio structure must also explain strong transit timing variations (TTVs) observed near resonance. Besides an amplitude a period, sinusoidal TTV has phase. Often overlooked, phases effectively integration constants, encoding information about initial conditions or environment. Many TTVs resonance exhibit non-zero phases. This...