A5000587126- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Radio Astronomy Observations and Technology
- Advanced Measurement and Metrology Techniques
- CCD and CMOS Imaging Sensors
- Solar and Space Plasma Dynamics
- Advanced Optical Sensing Technologies
- Space Exploration and Technology
- Astronomical and nuclear sciences
- Advanced Frequency and Time Standards
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- Infrared Target Detection Methodologies
- Scientific Measurement and Uncertainty Evaluation
- solar cell performance optimization
- Optical measurement and interference techniques
Mount Wilson Observatory
2021-2024
Georgia State University
2022-2024
KU Leuven
2020-2023
Institute of Astronomy
2020-2023
Université Grenoble Alpes
2018-2023
Centre National de la Recherche Scientifique
2018-2023
Institut de Planétologie et d'Astrophysique de Grenoble
2018-2021
Michigan United
2020
University of Michigan–Ann Arbor
2020
VIB-KU Leuven Center for Microbiology
2020
Young stars are surrounded by a circumstellar disk of gas and dust, within which planet formation can occur. Gravitational forces in multiple star systems disrupt the disk. Theoretical models predict that if is misaligned with orbital plane stars, should warp break into precessing rings, phenomenon known as tearing. We present observations triple system GWOrionis, finding evidence for Our images show an eccentric ring planes outer The casts shadows on strongly warped intermediate region If...
Abstract Michigan InfraRed Combiner-eXeter (MIRC-X) is a new highly sensitive six-telescope interferometric imager installed at the CHARA Array that provides an angular resolution equivalent of up to 330 m diameter baseline telescope in J - and H -band wavelengths ( <?CDATA $\tfrac{\lambda }{2B}\sim 0.6$?> mas). We upgraded original Combiner (MIRC) instrument improve sensitivity wavelength coverage two phases. First, revolutionary sub-electron noise fast-frame-rate C-RED ONE camera based on...
The Gl 486 system consists of a very nearby, relatively bright, weakly active M3.5 V star at just 8 pc with warm transiting rocky planet about 1.3 R_Terra and 3.0 M_Terra that is ideal for both transmission emission spectroscopy testing interior models telluric planets. To prepare future studies, we collected light curves seven new transits observed the CHEOPS space mission radial velocities obtained MAROON-X/Gemini North CARMENES/Calar Alto telescopes, together previously published...
The Michigan Young Star Imager at CHARA (MYSTIC) is a K-band interferometric beam combining instrument funded by the U.S. National Science Foundation, designed primarily for imaging sub-au scale disk structures around nearby young stars and to probe planet formation process.Installed Array in July 2021, with baselines up 331 m, MYSTIC provides maximum angular resolution of λ∕2B ∼ 0.7 mas.The injects phase-corrected light from array into inexpensive, single-mode, polarization maintaining...
Abstract Rapid rotation and nonradial pulsations enable Be stars to build decretion disks, where the characteristic line emission forms. A major but unconstrained fraction of owe their rapid mass angular momentum transfer in a binary. The faint, stripped companions can be helium-burning subdwarf OB-type (sdOBs), white dwarfs (WDs), or neutron stars. We present optical/near-infrared Center for High Angular Resolution Astronomy (CHARA) interferometry 37 selected spectroscopic indications...
Many classical Be stars acquire their very rapid rotation by mass- and angular-momentum transfer in massive binaries, marking the first phase of evolutionary chain. Later-stage products such as Be+subdwarf- Be+neutron-star binaries (Be X-ray binaries), are also well known, although search for definitive proof Be+white dwarf companions is ongoing. Short-lived intermediate-phase objects, that is, past interaction stage but with a donor star has not yet reached end its evolution or contraction,...
ABSTRACT We present updated orbital elements for the Wolf–Rayet (WR) binary WR 140 (HD 193793; WC7pd + O5.5fc). The new were derived using previously published measurements along with 160 radial velocity across 2016 periastron passage of 140. Additionally, four astrometry collected CHARA Array. With these measurements, we derive stellar masses $M_{\rm WR} = 10.31\pm 0.45 \, \mathrm{M}_\odot$ and O} 29.27\pm 1.14 \mathrm{M}_{\odot }$. also include a discussion evolutionary history this system...
Classical Be stars are possible products of close binary evolution, in which the mass donor becomes a hot, stripped O or B-type subdwarf (sdO/sdB), and gainer spins up grows disk to become star. While several Be+sdO binaries have been identified, dynamical masses other fundamental parameters available only for single system, limiting confrontation with evolution models. In this work, we present direct interferometric detections sdO companions three 28 Cyg, V2119 60 all were previously found...
Abstract The inner regions of protoplanetary disks host many complex physical processes such as star–disk interactions, magnetic fields, planet formation, and the migration new planets. To study directly this region requires milliarcsecond angular resolution, beyond diffraction limit world's largest optical telescopes even too small for millimeter-wave interferometer Atacama Large Millimeter/submillimeter Array (ALMA). However, we can use infrared interferometers to image astronomical unit....
Abstract To accurately characterize the planets a star may be hosting, stellar parameters must first well determined. τ Ceti is nearby solar analog and often target for exoplanet searches. Uncertainties in observed rotational velocities have made constraining Ceti’s inclination difficult. For planet candidates from radial velocity (RV) observations, this leads to substantial uncertainties planetary masses, as only minimum mass ( <?CDATA $m\sin i$?> <mml:math...
Abstract Stars with initial masses larger than 8 M ⊙ undergo substantial mass loss through mechanisms that remain elusive. Unraveling the origins of this is important for comprehending evolutionary path these stars, type supernova explosion, and whether they become neutron stars or black hole remnants. In 2022 December, RW Cep experienced Great Dimming in its visible brightness, presenting a unique opportunity to understand mass-loss mechanisms. Our previous observations from CHARA Array,...
Context. Luminous Blue Variables (LBVs) are thought to be in a transitory phase between O stars on the main-sequence and Wolf-Rayet stage. Recent studies suggest that they might formed through binary interaction. Only few known systems but their multiplicity fraction is uncertain. Aims. This study aims at deriving among Galactic (confirmed candidate) LBV population. We combine multi-epoch spectroscopy long-baseline interferometry. Methods. use cross-correlation measure radial velocities....
Context. Within the framework of second-generation instrumentation Very Large Telescope Interferometer European Southern Observatory we have developed four-telescope beam combiner in integrated optics. Aims. We optimized performance such combiners, for first time near-infrared K band, GRAVITY instrument dedicated to study close environment galactic centre black hole by precision narrow-angle astrometry and interferometric imaging. Methods. design optics chip manufacturing technology as well,...
The study of the multiplicity massive stars gives hints on their formation processes and evolutionary paths, which are still not fully understood. Large separation binaries (>50 milliseconds arc, mas) can be probed by adaptive-optics-assisted direct imaging sparse aperture masking, while close resolved photometry spectroscopy. However, optical long baseline interferometry is mandatory to establish Galactic at gap between 1 50 mas. In this paper, we aim demonstrate capability new...
The cool hypergiant star RW Cephei is currently in a deep photometric minimum that began several years ago. This event bears strong similarity to the Great Dimming of red supergiant Betelgeuse occurred 2019-2020. We present first resolved images we obtained with CHARA Array interferometer. angular diameter and Gaia distance estimates indicate stellar radius 900 - 1760 R_sun which makes Cep one largest stars known Milky Way. reconstructed, near-infrared show striking asymmetry disk...
Abstract Vortex fiber nulling (VFN) is a technique for detecting and characterizing faint companions at small separations from their host star. A near-infrared (∼2.3 μ m) VFN demonstrator mode was deployed on the Keck Planet Imager Characterizer (KPIC) instrument Observatory presented earlier. In this Letter, we present first companion detections. Three targets, HIP 21543 Ab, 94666 50319 B, were detected with host–companion flux ratios between 70 430 within one diffraction beamwidth ( λ / D...
Abstract The 30 yr orbit of the Cepheid Polaris has been followed with observations by Center for High Angular Resolution Astronomy (CHARA) Array from 2016 through 2021. An additional measurement made speckle interferometry at Apache Point Observatory. Detection companion is complicated its comparative faintness—an extreme flux ratio. diameter measurements appear to show some variation pulsation phase. Astrometric positions were measured a custom grid-based model-fitting procedure and...
We present the design for MYSTIC, Michigan Young STar Imager at CHARA. MYSTIC will be a K-band, cryogenic, 6-beam combiner Georgia State University CHARA telescope array. The follows image-plane combination scheme of MIRC instrument where single-mode fibers bring starlight into nonredundant fringe pattern to feed spectrograph. Beams injected in polarization-maintaining outside cryogenic dewar and then transported through vacuum feedthrough 220K cold volume is achieved light dispersed. use...
Context. FU Orionis is the archetypal FUor star, a subclass of young stellar object (YSO) that undergo rapid brightening events, often gaining 4-6 magnitudes on timescales days. This associated with massive increase in accretion; one most ubiquitous processes astrophysics from planets and stars to super-massive black holes. We present multi-band interferometric observations Ori circumstellar environment, including first J-band YSO. Aims. investigate morphology temperature gradient inner-most...
The distortions of absorption line profiles caused by photospheric brightness variations on the surfaces cool, main-sequence stars can mimic or overwhelm radial velocity (RV) shifts due to presence exoplanets. latest generation precision RV spectrographs aims detect amplitudes $\lesssim 10$ cm s$^{-1}$, but requires mitigation stellar signals. Statistical techniques are being developed differentiate between Keplerian and activity-related perturbations. Two important challenges, however,...
Time series of spectroscopic, speckle-interferometric, and optical long-baseline-interferometric observations confirm that $\nu$ Gem is a hierarchical triple system. It consists an inner binary composed two B-type stars outer classical Be star. Several photospheric spectral lines the components were disentangled, revealing with very different rotational broadening ($\sim$260 $\sim$140 kms$^{-1}$, respectively), while star remain undetected. From combined spectroscopic astrometric orbital...
MIRC-X is a new beam combination instrument at the CHARA array that enables 6-telescope interferometric imaging on object classes until now have been out of reach for milliarcsecond-resolution imaging. As part an instrumentation effort lead by University Exeter and Michigan, we equipped MIRC with ultra-low read-noise detector system extended wavelength range to J H- band. The first phase commissioning was successfully completed in June 2017. In 2018 will commission polarisation control...
MIRC-X is an upgrade of the six-telescope infrared beam combiner at CHARA telescope array, world's largest baseline interferometer in optical/infrared, located Mount Wilson Observatory Los Angeles. The upgraded instrument features ultra-low noise and fast frame rate camera (SAPHIRA detector) based on e-APD technology. We report sensitivity work first light results detail focusing detector characteristics software architecture.
We present the first visual orbit for nitrogen-rich Wolf-Rayet binary, WR 133 (WN5o + O9I) based on observations made with CHARA Array and MIRC-X combiner. This represents a WN star only third orbit. The has period of 112.8 d, moderate eccentricity 0.36, separation $a$= 0.79 mas sky. combine an SB2 Gaia parallax to find that derived masses component stars are $M_{\rm WR}$ = $9.3\pm1.6 M_\odot$ O}$ $22.6\pm 3.2 M_\odot$, large errors owing nearly face-on geometry system combined in...
The Michigan Young STar Imager at CHARA (MYSTIC) is a K-band interferometric beam combining instrument funded by the United States National Science Foundation, designed primarily for imaging sub-au scale disk structures around nearby young stars and to probe planet formation process. Installed array in July 2021, with baselines up 331 meters, MYSTIC provides maximum angular resolution of λ/2B ∼ 0.7 mas. injects phase corrected light from into inexpensive, single-mode, polarization...