A5044393766- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Geomagnetism and Paleomagnetism Studies
- Solar and Space Plasma Dynamics
- Astrophysical Phenomena and Observations
- Topological Materials and Phenomena
- History and Developments in Astronomy
- Photonic and Optical Devices
- Astrophysics and Cosmic Phenomena
- Statistical and numerical algorithms
- Mechanical and Optical Resonators
- Pulsars and Gravitational Waves Research
- Geological and Geophysical Studies
- Time Series Analysis and Forecasting
- Geological Modeling and Analysis
- High-pressure geophysics and materials
- Phytochemical Studies and Bioactivities
- Plant biochemistry and biosynthesis
- CCD and CMOS Imaging Sensors
University of Hawaii System
2022-2025
The University of Sydney
2019-2024
University of Hawaiʻi at Mānoa
2024
University of California, Berkeley
2024
Aarhus University
2019-2022
Google (United States)
2018
Foreman-Mackey et al., (2021). exoplanet: Gradient-based probabilistic inference for exoplanet data & other astronomical time series. Journal of Open Source Software, 6(62), 3285, https://doi.org/10.21105/joss.03285
In this paper we present a catalog of 4584 eclipsing binaries observed during the first two years (26 sectors) TESS survey. We discuss selection criteria for binary candidates, detection hither-to unknown systems, determination ephemerides, validation and triage process, derivation heuristic estimates ephemerides. Instead keeping to widely used discrete classes, propose star morphology classification based on dimensionality reduction algorithm. Finally, statistical properties sample,...
Abstract We describe the discovery of a solar neighborhood ( d = 468 pc) binary system with main-sequence sunlike star and massive noninteracting black hole candidate. The spectral energy distribution visible is described by single stellar model. derive parameters from high signal-to-noise Magellan/MIKE spectrum, classifying as T eff 5972 K, <?CDATA $\mathrm{log}g=4.54$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>g</mml:mi>...
PHOEBE 2 is a Python package for modeling the observables of eclipsing star systems, but until now has focused entirely on forward-model -- that is, generating synthetic model given fixed values large number parameters describing system and observations. The inverse problem, obtaining orbital stellar observational data, more complicated computationally expensive as it requires set forward-models to determine which uncertainties best represent available data. process determining solution also...
We study the fraction of stars in and around {\delta} Scuti instability strip that are pulsating, using {\em Gaia} DR2 parallaxes to derive precise luminosities. classify a sample over 15,000 Kepler} A F into Sct non-{\delta} stars, paying close attention variability could have other origins. find 18 per cent their dominant frequency above Kepler long-cadence Nyquist (periods < 1 hr), 30 some super-Nyquist variability. analyse pulsator as function effective temperature luminosity, finding...
The sparsely sampled time-series photometry from Gaia/ Data Release 3 (DR3) led to the discovery of more than 100,000 main-sequence non-radial pulsators. majority these were further scrutinised by uninterrupted high-cadence space assembled Transiting Exoplanet Survey Satellite (TESS). We combined DR3 and TESS photometric light curves estimate internal physical properties gravity-mode performed asteroseismic analyses with two major aims: 1) measure near-core rotation frequency its evolution...
Abstract Based on the rate of change its orbital period, PSR J2043+1711 has a substantial peculiar acceleration 3.5 ± 0.8 mm s –1 yr , which deviates from predicted by equilibrium Milky Way (MW) models at 4 σ level. The magnitude is too large to be explained disequilibrium effects MW interacting with orbiting dwarf galaxies (∼1 ), and small caused period variations due pulsar being redback. We identify examine two plausible causes for anomalous acceleration: stellar flyby, long-period...
We have examined the period–luminosity (P–L) relation for δ Scuti stars using Gaia DR2 parallaxes. included 228 from catalogue of Rodríguez et al., as well 1124 observed in 4-yr Kepler mission. For each star, we considered dominant pulsation period, and used parallaxes extinction corrections to determine absolute V magnitudes. Many fall along a sequence P–L coinciding with fundamental-mode pulsation, while others pulsate shorter period overtones. The latter tend higher effective...
We present the first results from Transiting Exoplanet Survey Satellite (TESS) on rotational and pulsational variability of magnetic chemically peculiar A-type stars. analyse TESS 2-min cadence data sectors 1 2 a sample 83 Five new rapidly oscillating Ap (roAp) stars are announced. One these pulsates with periods around 4.7 min, making it shortest period roAp star known to date. Four out five multiperiodic. Three singly periodic one show presence mode splitting. Individual frequencies...
Abstract We studied 89 A- and F-type members of the Pleiades open cluster, including five escaped members. measured projected rotational velocities ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>v</mml:mi> <mml:mi>sin</mml:mi> <mml:mi>i</mml:mi> </mml:math> ) for 49 stars confirmed that stellar rotation causes a broadening main sequence in color–magnitude diagram. Using time-series photometry from NASA’s TESS Mission (plus one star observed by...
In asteroseismology, the surface effect refers to a disparity between observed and modelled frequencies in stars with solar-like oscillations. It originates from improper modelling of layers. Correcting usually requires using functions free parameters, which are conventionally fitted frequencies. On basis that correction should vary smoothly across H--R diagram, we parameterize it as simple function gravity, effective temperature, metallicity. We determine this by fitting wide range stars....
Context. The Gaia mission has delivered hundreds of thousands variable star light curves in multiple wavelengths. Recent work demonstrates that these can be used to identify (non-)radial pulsations OBAF-type stars, despite their irregular cadence and low curve precision, the order a few millimagnitudes. With considerably more precise TESS photometry, we revisited candidate pulsators conclusively ascertain nature variability. Aims. We seek re-classify with first two years photometry for...
We report the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA's Transiting Exoplanet Survey Satellite (TESS). The transit signal was detected by TESS and confirmed to be planetary origin radial velocity observations. An analysis photometry, Minerva-Australis, FEROS, HARPS velocities, asteroseismic stellar oscillations reveals that has mass $M_P=0.138\pm0.023$\,$\rm{M_J}$ ($43.9\pm7.3$\,$M_{\rm \oplus}$), radius $R_P=0.639\pm0.013$\,$\rm{R_J}$...
Abstract We observed HD 19467 B with JWST’s NIRCam in six filters spanning 2.5–4.6 μ m the long-wavelength bar coronagraph. The brown dwarf was initially identified through a long-period trend radial velocity of G3V star 19467. subsequently detected via coronagraphic imaging and spectroscopy, characterized as late-T type an approximate temperature ∼1000 K. part GTO science program, demonstrating first use Long Wavelength Bar mask. object all (contrast levels 2 × 10 −4 to −5 ) at separation...
Abstract The Galactic bulge is critical to our understanding of the Milky Way. However, due lack reliable stellar distances, structure and kinematics bulge/bar beyond center have remained largely unexplored. Here, we present a method measure distances luminous red giants using period–amplitude–luminosity relation anchored Large Magellanic Cloud, with random uncertainties 10%–15% systematic errors below 1%–2%. We apply this data from Optical Gravitational Lensing Experiment 190,302 stars in...
Abstract The degree of alignment between a star’s spin axis and the orbital plane its planets (the stellar obliquity) is related to interesting poorly understood processes that occur during planet formation evolution. Hot Jupiters orbiting hot stars (≳6250 K) display wide range obliquities, while similar cool are preferentially aligned. Tidal dissipation expected be more rapid in with thick convective envelopes, potentially explaining this trend. Evolved provide an opportunity test damping...
We systematically searched for gravity- and Rossby-mode period spacing patterns in Kepler eclipsing binaries with $\gamma$ Doradus pulsators. These stars provide an excellent opportunity to test the theory of tidal synchronisation angular momentum transport F- A-type stars. discovered 35 systems that show clear patterns, including spectroscopic binary KIC 10080943. Combined 45 non-eclipsing Dor components have been found using pulsation timing, we measured their near-core rotation rates...
ABSTRACT We have used NASA’s TESS mission to study catalogued δ Scuti stars. examined light curves for 434 stars, including many which few previous observations exist. found that 62 are not pulsators, with most instead showing variability from binarity. For the 372 we provide a catalogue of period and amplitude dominant pulsation mode. Using Gaia DR3 parallaxes, place stars in period–luminosity (P–L) diagram confirm findings lie on ridge corresponds fundamental radial mode, others fall...
We perform mode identification for five $\delta$ Scuti stars in the Pleiades star cluster, using custom light curves from K2 photometry. By creating \'echelle diagrams, we identify radial and dipole ridges, comprising a total of 28 16 modes across stars. also suggest possible identities those that lie offset ridges. calculate non-rotating stellar pulsation models to verify our identifications, finding good agreement within age metallicity constraints cluster. find all stars, least dense are...
ABSTRACT We use TESS 10-min full-frame images (Sectors 27–55) to study a sample of 1708 stars within 500 pc the Sun that lie in narrow colour range centre δ Scuti instability strip (0.29 &lt; GBP − GRP 0.31). Based on Fourier amplitude spectra, we identify 848 stars, as well 47 eclipsing or contact binaries. The strongest pulsation modes some fall period–luminosity relation fundamental radial mode but many correspond overtones are approximately factor two higher frequency. Many...
Abstract δ Scuti variables are found at the intersection of classical instability strip and main sequence on Hertzsprung–Russell diagram. With space-based photometry providing millions light curves A-F type stars, we can now probe occurrence rate pulsations in detail. Using 30 minutes cadence from NASA's Transiting Exoplanet Survey Satellite's first 26 sectors, identify variability 103,810 stars within 5–24 cycles per day down to a magnitude T = 11.25. We fit period–luminosity relation...
Strong magnetic fields in chemically peculiar A-type (Ap) stars typically suppress low-overtone pressure modes (p modes) but allow high-overtone p to be driven. KIC 11296437 is the first star show both. We obtained and analysed a Subaru spectrum, from which we that has abundances similar other Ap stars, estimate mean field modulus of $2.8\pm0.5$ kG. The same spectrum rules out double-lined spectroscopic binary, use techniques rule binarity over wide parameter space, so two pulsation types...