A5007759295- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Semiconductor Quantum Structures and Devices
- Spectroscopy and Quantum Chemical Studies
- Astronomical Observations and Instrumentation
- Atmospheric Ozone and Climate
- Adaptive optics and wavefront sensing
- Planetary Science and Exploration
- Quantum and electron transport phenomena
- Spectroscopy and Laser Applications
- Solar and Space Plasma Dynamics
- Quantum optics and atomic interactions
- Semiconductor Lasers and Optical Devices
- Scientific Research and Discoveries
- History and Developments in Astronomy
- Laser-Matter Interactions and Applications
- Quantum Information and Cryptography
- Bee Products Chemical Analysis
- Geophysics and Gravity Measurements
- Space Science and Extraterrestrial Life
- Molecular Spectroscopy and Structure
- Optical Wireless Communication Technologies
- Advanced Chemical Physics Studies
University of California, Riverside
2020-2024
University of Washington
2017-2024
University of Central Florida
2023-2024
Planetary Science Institute
2017-2023
Aix-Marseille Université
2023
Centre National de la Recherche Scientifique
2023
California Institute of Technology
2023
Space Telescope Science Institute
2023
Goddard Space Flight Center
2023
Laboratoire d’Astrophysique de Marseille
2023
Abstract The search for habitable planets has revealed many that can vary greatly from an Earth analog environment. These include highly eccentric orbits, giant planets, different bulk densities, relatively active stars, and evolved stars. This work catalogs all found to reside in the zone (HZ) provides HZ boundaries, orbit characterization, potential spectroscopic follow-up observations. Demographics of are compared with a full catalog exoplanets. Extreme within highlighted, how their...
The degenerate-four-wave-mixing response of excitons in GaAs quantum wells is modeled using the optical Bloch equations including exciton-exciton interactions. results display a strong dependence on polarization excitation pulses. model predicts intensity and dependences time-integrated signal characteristic temporal features time-resolved excellent agreement with observations.
A three-pulse degenerate four-wave-mixing experiment and its theoretical analysis reveal contributions of local field biexciton effects to the nonlinear optical response two-dimensional exciton. Quantum beats with a frequency equivalent binding energy appear only for specific polarizations. Polarization-dependent spectrally resolved four-wave mixing shows an additional peak that is separated from 1s heavy-hole exciton line by energy. These experimental results are in good agreement selection...
Beats in the transient four-wave-mixing signal from strongly inhomogeneously broadened semiconductor quantum wells are observed. Based on their phase and polarization properties, beats assigned to biexcitons mesoscopically disordered material. With increasing excitation intensity a halving of beat period is observed accurately reproduced by calculations including fifth-order contributions. \textcopyright{} 1996 The American Physical Society.
ABSTRACT NASA is engaged in planning for a Habitable Worlds Observatory (HabWorlds ), coronagraphic space mission to detect rocky planets habitable zones and establish their habitability. Surface liquid water central the definition of planetary Photometric polarimetric phase curves starlight reflected by an exoplanet can reveal ocean glint, rainbows, other phenomena caused scattering clouds or atmospheric gas. Direct imaging missions are optimized near quadrature, but HabWorlds ’ coronagraph...
We describe the HIgh Precision Polarimetric Instrument (HIPPI), a polarimeter built at UNSW Australia and used on Anglo-Australian Telescope (AAT). HIPPI is an aperture using ferro-electric liquid crystal modulator. measures linear polarization of starlight with sensitivity in fractional ~4 x 10$^{-6}$ low objects precision better than 0.01% highly polarized stars. The detectors have high dynamic range allowing observations brightest stars sky as well much fainter objects. telescope AAT...
We present linear polarization observations of the exoplanet system HD 189733 made with HIgh Precision Polarimetric Instrument (HIPPI) on Anglo-Australian Telescope (AAT). The have higher precision than any previously reported for this object. They do not show large amplitude variations by Berdyugina et al. 2008 and 2011. Our results are consistent data presented Wiktorowicz 2015. A formal least squares fit a Rayleigh-Lambert model yields 29.4 +/- 15.6 parts-per-million. observe background...
We present broad-band photometry of five transits in the planetary system WASP-36, totaling 17 high-precision light curves. Four were simultaneously observed four passbands (g, r, i, z), using telescope-defocussing technique, and achieving scatters less than 1 mmag per observation. used these data to improve measured orbital physical properties system, obtain an optical transmission spectrum planet. a decreasing radius from bluer redder with confidence level more 5 sigma. The variation is...
Understanding the physical characteristics of Venus, including its atmosphere, interior, and evolutionary pathway with respect to Earth, remains a vital component for terrestrial planet evolution models emergence and/or decline planetary habitability. A statistical strategy evaluating pathways planets lies in atmospheric characterization exoplanets, where sample size provides sufficient means determining required runaway greenhouse conditions. Observations potential exoVenuses can help...
Abstract Saturn's moon Titan is an enigmatic icy world whose surface constantly modified by its active, Earthlike precipitation system. Here, we propose the Titan's Hydrocarbons: Uncovering New Dimensions of Evolutionary pRocesses (THUNDER) mission concept to investigate how reflects nature interior and active hydrocarbon cycle. This will change our understanding through three science objectives: characterizing heat material transport properties outer layer, tracing liquid storage across...
Abstract The search for life beyond the solar system remains a primary goal of current and near-future missions, including NASA’s upcoming Habitable Worlds Observatory (HWO). However, research into determining habitability terrestrial exoplanets has been primarily focused on comparisons to modern-day Earth. Additionally, characterization strategies focus unpolarized flux from these worlds, taking account only fraction informational content reflected light. Better understanding changes in...
We report observations of the linear polarisation a sample 50 nearby southern bright stars measured to median sensitivity $\sim$4.4 $\times 10^{-6}$. find larger polarisations and more highly polarised than in previous PlanetPol survey northern stars. This is attributed dustier interstellar medium mid-plane Galaxy, together with population containing B-type leading intrinsically stars, as well using wavelength sensitive intrinsic late-type giants. Significant had been identified for only six...
Accurate measurements of the physical characteristics a large number exoplanets are useful to strongly constrain theoretical models planet formation and evolution, which lead variety planetary-system configurations that have been observed. We present study planetary systems WASP-45 WASP-46, both composed main-sequence star close-in hot Jupiter, based on 29 new high-quality light curves transits events. In particular, one transit b four WASP-46 were simultaneously observed in optical filters,...
We present linear polarization measurements of nearby FGK dwarfs to parts-per-million (ppm) precision. Before making any allowance for interstellar polarization, we found that the active stars within sample have a mean 28.5 ± 2.2 ppm, while inactive 9.6 1.5 ppm. Amongst stars, initially no difference between debris disc host (9.1 2.5 ppm) and other (9.9 1.9 ppm). develop model magnitude direction stars. When correct observations estimated obtain 23.0 ppm 7.8 2.9 The data indicate whilst some...
We report time-resolved degenerate four-wave-mixing experiments on a high-quality single GaAs quantum well. The signals for parallel and cross-polarized exciting pulses show pronounced beats with different frequencies corresponding to the heavy/light-hole splitting biexciton binding energy, respectively. Comparison of experimental data solutions optical Bloch equations phenomenological model system shows that these features result from strong contributions biexcitonic state. importance...
ABSTRACT Debris discs are typically revealed through the presence of excess emission at infrared wavelengths. Most exhibit mid- and far-infrared wavelengths, analogous to solar system’s Asteroid Edgeworth-Kuiper belts. Recently, stars with strong (∼1%) near-infrared wavelengths were identified interferometric measurements. Using HIgh Precision Polarimetric Instrument, we examined a sub-sample these hot dust (and appropriate controls) parts-per-million sensitivity in SDSS g ′ (green) r (red)...
We describe the incorporation of polarized radiative transfer into atmospheric modelling code VSTAR (Versatile Software for Transfer Atmospheric Radiation). Using a vector discrete-ordinate we are able to generate maps radiance and polarization across disc planet, integrate over these get full-disc polarization. In this way obtain disc-resolved, phase-resolved spectrally-resolved intensity any wide range atmopsheres that can be modelled with VSTAR. have tested by reproducing standard...
The properties of dust in the interstellar medium (ISM) nearest Sun are poorly understood because low column densities toward nearby stars induce little photometric reddening, rendering grains largely undetectable. Stellar polarimetry offers one pathway to deducing this diffuse material. Here we present multi-wavelength aperture measurements seven bright chosen probe polarization near edge Local Hot Bubble (LHB) - an amorphous region relatively density gas and extending ~70-150 pc from Sun....
Abstract We report observations of the linear polarization WASP-18 system, which harbors a massive (∼10 M J ) planet orbiting close to its star with an orbital period 0.94 days. find that system is polarized at ∼200 parts-per-million (ppm), likely from interstellar medium predominantly, no strong evidence for phase-dependent modulation reflected light planet. set upper limit 40 ppm (99% confidence level) on amplitude planetary signal. compare results models number processes may produce in...
ABSTRACT Debris discs around main sequence stars have been extensively characterized from infrared to millimetre wavelengths through imaging, spectroscopic, and total intensity (scattered light and/or thermal emission) measurements. Polarimetric observations only used sparingly interpret the composition, structure, size of dust grains in these discs. Here, we present new multiwavelength aperture polarization with parts-per-million sensitivity a sample twelve bright debris discs, spanning...
Abstract In this, the first of three articles on optical absorption electrons in half-filled Peierls-distorted chains, we present analytical results for non-interacting tight-binding electrons. We carefully derive explicit expressions current operator, dipole transition matrix elements and with a cosine dispersion relation bandwidth W dimerization parameter δ. New correction (η) terms to operator are identified. A broad band-to-band is found frequency range Wδ < ω whose shape determined by...
We describe a novel three-pulse degenerate four-wave mixing configuration that permits the direct observation of coherence between σ+ and σ− exciton states in GaAs quantum well excited two-photon process. It is found phase two single heavy-hole decays with time constant considerably longer than dephasing these ground state (interband coherence). All experimental data are described by numerical solutions optical Bloch equations for phenomenological multilevel model.
We have observed the active star $\xi$ Boo A (HD 131156A) with high precision broadband linear polarimetry contemporaneously circular spectropolarimetry. find both signals are modulated by 6.43 day rotation period of A. The from two techniques 0.25 out phase, consistent polarization resulting differential saturation spectral lines in global transverse magnetic field. mean magnitude signal is ~4 ppm/G but its structure complex and amplitude variations suppressed relative to longitudinal...