A5008842295- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- History and Developments in Astronomy
- Calibration and Measurement Techniques
- Magnetic confinement fusion research
- Optical Polarization and Ellipsometry
- Scientific Research and Discoveries
- Pulsars and Gravitational Waves Research
- Optical measurement and interference techniques
- Space Exploration and Technology
- Plasma Diagnostics and Applications
- Spectroscopy and Laser Applications
- Atomic and Molecular Physics
- Electron and X-Ray Spectroscopy Techniques
- Advanced Fiber Laser Technologies
- Laser-Plasma Interactions and Diagnostics
- Advanced Measurement and Metrology Techniques
- Particle accelerators and beam dynamics
- Optical Systems and Laser Technology
Columbia State Community College
2020-2024
Tennessee State University
2010-2019
Physical Sciences (United States)
2016
University of California, Berkeley
2007-2009
Berkeley College
2007-2009
Vassar College
2004-2006
Massachusetts Institute of Technology
2001-2006
California Institute of Technology
2006
Technicolor (United States)
2003-2006
Princeton Scientific (United States)
2001
The dwarf stars in the 26 year period binary alpha Com were predicted to eclipse each other early 2015. That prediction was based on an orbit model made with over 600 astrometric observations using micrometers, speckle interferometry, and long baseline optical interferometry. Unfortunately, it has been realized recently that position angle measurements for three of from ~100 years ago error by 180 degrees, which skewed orbital fit. likely 2 months earlier than predicted, at point system low...
The two-dimensional (2D) radial vs poloidal structure of edge turbulence in the Alcator C-Mod tokamak [I. H. Hutchinson, R. Boivin, P. T. Bonoli et al., Nucl. Fusion 41, 1391 (2001)] was measured using fast cameras and compared with three-dimensional numerical simulations plasma turbulence. main diagnostic is gas puff imaging, which visible Dα emission from a localized D2 viewed along local magnetic field line. observed fluctuations have typical scale ≈1 cm, often strong maxima (“blobs”)...
Differential astrometry measurements from the Palomar High-precision Astrometric Search for Exoplanet Systems have been combined with lower precision single-aperture covering a much longer timespan (from eyepiece measurements, speckle interferometry, and adaptive optics) to determine improved visual orbits 20 binary stars. In some cases, radial velocity observations exist constrain full three-dimensional orbit component masses. The of one these binaries---alpha Com (HD 114378)---shows that...
The Palomar High-precision Astrometric Search for Exoplanet Systems monitored 51 subarcsecond binary systems to evaluate whether tertiary companions as small Jovian planets orbited either the primary or secondary stars, perturbing their otherwise smooth Keplerian motions. Six binaries are presented that show evidence of substellar orbiting star. Of these six systems, likelihoods two detected perturbations represent real objects considered be "high confidence", while remaining four less...
We present high precision radial velocities (RVs) of double-lined spectroscopic binary stars HD78418, HD123999, HD160922, HD200077 and HD210027. They were obtained based on the resolution echelle spectra collected with Keck I/Hires, Shane/CAT/Hamspec TNG/Sarge telescopes/spectrographs over years 2003-2008 as a part TATOOINE search for circumbinary planets. The RVs computed using our novel iodine cell technique double-line stars. is order 1-10 m/s. Our combined archival visibility...
In the context of ESA M5 (medium mission) call we proposed a new satellite mission, Theia, based on relative astrometry and extreme precision to study motion very faint objects in Universe. Theia is primarily designed local dark matter properties, existence Earth-like exoplanets our nearest star systems physics compact objects. Furthermore, about 15 $\%$ mission time was dedicated an open observatory for wider community propose complementary science cases. With its unique metrology system...
Abstract A single-lined spectroscopic orbit for the M giant in X-ray binary IGR J16194−2810 is determined from a time series of optical spectra. The orbital period 192.5 days twice that photometric period, confirming system an ellipsoidal variable. identified as first ascent approaching red tip. primary neutron star (NS) with its companion filling Roche lobe, verifying classification low-mass (LMXB). Stellar C, N, O, and Fe abundances are derived O values typical field [Fe/H] = −0.14. does...
Abstract T CrB is among the brightest novae. It recurrent with outbursts happening approximately every 80 yr. The next outburst imminent, expected in 2025. binary consists of an M4 III red giant (RG) secondary and a white dwarf (WD) primary. A time series spectra RG was obtained between 2022 2024. Radial velocities (RVs) from these data were combined literature RVs updated orbit computed. circular to high precision has period 227.5494 ± 0.0049 days for solution. An eccentric solution yields...
Precise near-infrared radial velocimetry enables efficient detection and transit verification of low-mass extrasolar planets orbiting M dwarf hosts, which are faint for visible-wavelength velocity surveys. The TripleSpec Exoplanet Discovery Instrument, or TEDI, is the combination a variable-delay Michelson interferometer medium-resolution (R=2700) spectrograph on Palomar 200" Hale Telescope. We used TEDI to monitor GJ 699, nearby mid-M dwarf, over 11 nights spread across 3 months. Analysis...
Sky survey telescopes and powerful targeted play complementary roles in astronomy. In order to investigate the nature characteristics of motions very faint objects, a flexibly-pointed instrument capable high astrometric accuracy is an ideal complement current surveys unique tool for precision astrophysics. Such space-based mission will push frontier astrometry from evidence Earth-mass habitable worlds around nearest stars, distant Milky Way out Local Group galaxies. As we enter era James...
We have used the Palomar Testbed Interferometer to perform very high precision differential astrometry on 025 separation binary star HD 171779. In 70 minutes of observation, we achieve a measurement uncertainty ≈9 μas in one axis, consistent with theoretical expectations. Night-to-night repeatability over four nights is at level 16 μas. This method narrow angle may be extremely useful for searching planets masses as small 0.5MJ around previously neglected class stars—so-called speckle...
Hostile tidal forces may inhibit the formation of Jovian planets in binaries with semimajor axes ≲50 AU, that might be called "close" this context. As an alternative to situ planet formation, a binary can acquire giant when one its original members is replaced dynamical interaction another star hosts planet. Simple scaling relations for structure and evolution clusters, coupled analytic arguments regarding binary-single binary-binary scattering, indicate processes deposit <1% close binaries....
We present preliminary results of the first and on-going radial velocity survey for circumbinary planets. With a novel technique employing an iodine absorption cell we achieve unprecedented RV precision up to 2 m/s double-lined binary stars. The high resolution spectra collected with Keck I/Hires, TNG/Sarg Shane/CAT/Hamspec telescopes/spectrographs over years 2003-2008 allow us derive RVs compute planet detection limits ten For this initial sample targets, can rule out planets on dynamically...
We ask if Earth-like planets (terrestrial mass and habitable-zone orbit) can be detected in multi-planet systems, using astrometric radial velocity observations. report here the preliminary results of double-blind calculations designed to answer this question.
We report the detections of a giant planet (MARVELS-7b) and brown dwarf candidate (MARVELS-7c) around primary star in close binary system, HD 87646. It is first system with more than one substellar circum-primary companion discovered to best our knowledge. The detection this was accomplished using multi-object Doppler instrument (KeckET) at Sloan Digital Sky Survey (SDSS) telescope. Subsequent radial velocity observations ET Kitt Peak National Observatory, HRS HET, "Classic" spectrograph...
A single-lined spectroscopic orbit for the M giant in X-ray binary IGR J16194-2810 is determined from a time-series of optical spectra. The orbital period 192.5 days twice that photometric period, confirming system an ellipsoidal variable. identified as first ascent approaching red tip. primary neutron star (NS) with its companion filling Roche lobe verifying classification Low-Mass (LMXB). Stellar C, N, O and Fe abundances are derived values typical field [Fe/H] = -0.14. does not have large...
μ Orionis was identified by spectroscopic studies as a quadruple-star system. Seventeen high-precision differential astrometry measurements of Ori have been collected the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES). These show both motion long-period binary orbit and short-period perturbations superimposed on that caused each components in system being themselves binaries. The new enable orientations subsystems to be determined. Recent theoretical work predicts...
We present the orbital and physical parameters of a newly discovered low-mass detached eclipsing binary from All-Sky Automated Survey (ASAS) database: ASAS J011328-3821.1 A - member visual system with secondary component separated by about 1.4 seconds arc. The radial velocities were calculated high-resolution spectra obtained 1.9-m Radcliffe/GIRAFFE, 3.9-m AAT/UCLES 3.0-m Shane/HamSpec telescopes/spectrographs on basis TODCOR technique positions H_alpha emission lines. For analysis we used V...
The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) monitored 51 sub-arcsecond binary systems to determine precision orbits, study the geometries of triple and quadruple star systems, discover previously unknown faint astrometric companions as small giant planets.PHASES measurements made with Testbed Interferometer (PTI) from 2002 until PTI ceased normal operations in late 2008 are presented.Infrared differential photometry several PHASES targets were measured Keck...
Visible-light long baseline interferometry holds the promise of advancing a number important applications in fundamental astronomy, including direct measurement angular diameters and oblateness stars, orbits binary multiple star systems. To advance, field visible-light requires development instruments capable combining light from 15 baselines (6 telescopes) simultaneously. The Visible Imaging System for Interferometric Observations at NPOI (VISION) is new visible beam combiner Navy Precision...
Abstract We report 370 measures of 170 components binary and multiple-star systems, obtained from speckle imaging observations made with the Differential Speckle Survey Instrument at Lowell Observatory’s Discovery Channel Telescope in 2015 through 2017. Of systems studied, 147 are stars, 10 seen as triple 1 quadruple system is measured. Seventy-six high-quality nondetections 15 newly resolved presented our observations. The uncertainty relative astrometry appears to be similar previous work...
We derive the absolute physical and orbital parameters for a sample of 18 detached eclipsing binaries from All-Sky Automated Survey (ASAS) data base based on available photometry our own radial velocity (RV) measurements. The RVs are computed using spectra we collected with 3.9-m Anglo-Australian Telescope (AAT) its University College London Echelle Spectrograph (UCLES), 1.9-m Radcliffe telescope Grating Instrument Radiation Analysis Fibre-Fed (GIRAFFE) at South African Astronomical...
We have determined spectroscopic orbits for five single-lined binaries, HD 100167, 135991, 140667, 158222, 217924. Their periods range from 60.6 to 2403 days and the eccentricities 0.20 0.84. Our spectral classes stars confirm that they are of solar type, F9–G5, all dwarfs. [Fe/H] abundances, spectroscopically, close value on average 0.12 greater than abundances a photometric calibration. Four rotating faster their predicted pseudosynchronous rotational velocities.
The Dharma Planet Survey (DPS) aims to monitor about 150 nearby very bright FGKM dwarfs (within 50 pc) during 2016–2020 for low-mass planet detection and characterization using the TOU high resolution optical spectrograph (|$R \approx 100\, 000$|, 380–900 nm). was initially mounted 2-m Automatic Spectroscopic Telescope at Fairborn Observatory in 2013–2015 conduct a pilot survey, then moved dedicated 50-inch automatic telescope on Mt. Lemmon 2016 launch survey. Here, we report first from...
The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) has monitored 37 subarcsecond binary systems to determine whether their Keplerian orbits are perturbed by faint astrometric companions either star.Software been developed evaluate the regions in a companion mass-period phase space which PHASES observations can exclude possibility of face-on orbit perturbations.We present results eight with masses as small those giant planets be excluded.