A5091785575- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Calibration and Measurement Techniques
- Geophysics and Gravity Measurements
- Astrophysical Phenomena and Observations
- Atmospheric Ozone and Climate
- Space Exploration and Technology
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Pulsars and Gravitational Waves Research
- Historical Astronomy and Related Studies
- Magnetic confinement fusion research
- Solar Radiation and Photovoltaics
- Planetary Science and Exploration
- Atmospheric and Environmental Gas Dynamics
- Geophysics and Sensor Technology
- Nuclear Physics and Applications
- Reservoir Engineering and Simulation Methods
Tennessee State University
2015-2024
Lawrence Livermore National Laboratory
2021
University of Arizona
2020
Middle Tennessee State University
2016
Center for Health, Exercise and Sport Sciences
2013
Trent University
2012
California Institute of Technology
2009
University of California, Los Angeles
2009
The University of Texas at Austin
1985-2008
Vanderbilt University
1981-2006
The G0 V star HD 166435 has been observed by the fiber-fed spectrograph ELODIE as one of targets in large extra-solar planet survey that we are conducting at Observatory Haute-Provence. We detected coherent, low-amplitude, radial-velocity variations with a period 3.7987 days, suggesting possible close-in planetary companion. Subsequently, initiated series high-precision photometric observations to search for transits and an additional Ca II H K measure level surface magnetic activity look...
Doppler measurements from Keck exhibit a sinusoidal periodicity in the velocities of G0 dwarf HD 209458, having semiamplitude 81 m s-1 and period 3.5239 days, which is indicative "51 Peg-like" planet with minimum mass (Msini) 0.62 MJup semimajor axis 0.046 AU. Follow-up photometry reveals drop 0.017 mag at predicted time (within errors) transit by companion based on velocities. This first extrasolar observed to its star. The radius derived magnitude dimming 1.42 RJup, consistent models...
We present a sample of 824 solar and late-type stars with X-ray luminosities rotation periods. This is used to study the relationship between stellar activity derive new estimate convective turnover time. From an unbiased subset this power law slope unsaturated regime, L_X / L_bol = Ro^β, fit as β= -2.70 +/- 0.13. inconsistent canonical β=-2 confidence 5 sigma, argues for additional term in dynamo number equation. simple scaling analysis implies ΔΩ/ Ω= Ω^0.7, i.e. differential solar-type...
High-precision, high-cadence radial velocity monitoring over the past 8 yr at W. M. Keck Observatory reveals evidence for a third planet orbiting nearby (4.69 pc) dM4 star GJ 876. The residuals of three-body Newtonian fits, which include 876 and Jupiter-mass companions b c, show significant power periodicity 1.9379 days. Self-consistently fitting data with model that includes an additional body this period significantly improves quality fit. These four-body (three-planet) fits find minimum...
We report precise Doppler measurements of GJ 436 (M2.5 V) obtained at Keck Observatory. The velocities reveal a planetary companion with orbital period 2.644 days, eccentricity 0.12 (consistent zero), and velocity semiamplitude K = 18.1 m s-1. minimum mass (M sin i) for the planet is 0.067MJup 1.2MNep 21MEarth, making it lowest exoplanet yet found around main-sequence star first candidate in Neptune-mass domain. (mass 0.41 M☉) only second M dwarf to harbor planet, joining two-planet system...
We present Hubble Space Telescope optical and near-ultraviolet transmission spectra of the transiting hot-Jupiter HD189733b, taken with repaired Imaging Spectrograph (STIS) instrument. The resulting cover range 2900-5700 Ang reach per-exposure signal-to-noise levels greater than 11,000 within a 500 bandwidth. used time series obtained during two transit events to determine wavelength dependance planetary radius measure exoplanet's atmospheric spectrum for first over this range. Our...
The hot Jupiter HD189733b is the most extensively observed exoplanet. Its atmosphere has been detected and characterised in transmission eclipse spectroscopy, its phase curve measured at several wavelengths. This paper brings together results of our campaign to obtain complete spectrum this planet from UV IR with HST, using STIS, ACS WFC3. We provide a new tabulation across entire visible range. radius ratio each wavelength band was rederived ensure consistent treatment bulk transit...
Doppler measurements from Subaru and Keck have revealed radial velocity variations in the V=8.15, G0IV star HD 149026 consistent with a Saturn-Mass planet 2.8766 day orbit. Photometric observations at Fairborn Observatory detected three complete transit events depths of 0.003 mag predicted times conjunction. is now second brightest transiting extrasolar planet. The mass star, based on interpolation stellar evolutionary models, 1.3 +/- 0.1 solar masses; together amplitude, K=43.3 m s^-1, we...
The water abundance in a planetary atmosphere provides key constraint on the planet's primordial origins because ice is expected to play an important role core accretion model of planet formation. However, content Solar System giant planets not well known sequestered clouds deep their atmospheres. By contrast, short-period exoplanets have such high temperatures that atmospheres gas phase, making it possible measure for these objects. We present precise determination 2 $M_\mathrm{Jup}$...
We present observations of seven transits and eclipses the transiting planet system HD 189733 taken with Spitzer IRAC at 8 microns. use a new correction for detector ramp variation double-exponential function. Our main findings are: (1) an upper limit on variability day-side flux 2.7% (68% confidence); (2) most precise set transit times measured planet, average accuracy 3 seconds; (3) lack transit-timing variations, excluding presence second planets in this above 20% mass Mars low-order...
Exoplanets that orbit close to their host stars are much more highly irradiated than Solar System counterparts. Understanding the thermal structures and appearances of these planets requires investigating how atmospheres respond such extreme stellar forcing. We present spectroscopic emission measurements as a function orbital phase ("phase-curve observations") for highly-irradiated exoplanet WASP-43b spanning three full planet rotations using Hubble Space Telescope. With data, we construct...
We present new, full-orbit observations of the infrared phase variations canonical hot Jupiter HD 189733b obtained in 3.6 and 4.5 μm bands using Spitzer Space Telescope. When combined with previous curve at 8.0 24 μm, these data allow us to characterize exoplanet's emission spectrum as a function planetary longitude search for local its vertical thermal profile atmospheric composition. utilize an improved method removing effects intrapixel sensitivity robustly extracting signals from data,...
Detailed characterization of exoplanets has begun to yield measurements their atmospheric properties that constrain the planets' origins and evolution. For example, past observations dayside emission spectrum hot Jupiter WASP-12b indicated its atmosphere a high carbon-to-oxygen ratio (C/O > 1), suggesting it had different formation pathway than is commonly assumed for giant planets. Here we report precise near-infrared transmission based on six transit with Hubble Space Telescope/Wide Field...
We report the discovery of a low-mass planet orbiting Gl 15 A based on radial velocities from Eta-Earth Survey using HIRES at Keck Observatory. Ab is with minimum mass Msini = 5.35 $\pm$ 0.75 M$_\oplus$, orbital period P 11.4433 0.0016 days, and an orbit that consistent circular. characterize host star variety techniques. Photometric observations Fairborn Observatory show no evidence for rotational modulation spots to limit ~0.1 mmag, thus supporting existence planet. detect second RV signal...
We present a high-precision radial velocity (RV) survey of 719 FGKM stars, which host 164 known exoplanets and 14 newly discovered or revised substellar companions. This catalog updated the orbital parameters long-period candidates, some have decades-longer observational baselines than they did upon initial detection. The range from warm sub-Neptunes super-Earths to cold gas giants. sample selection criteria, as well over 100,000 RV measurements, come Keck-HIRES, APF-Levy, Lick-Hamilton...
We present Hubble Space Telescope optical and near-IR transmission spectra of the transiting hot-Jupiter WASP-31b. The spectrum covers 0.3-1.7 $\mu$m at a resolution $R\sim$70, which we combine with Spitzer photometry to cover full-optical IR. is dominated by cloud-deck flat apparent wavelengths $>0.52\mu$m. cloud deck high altitudes low pressures, as it majority expected Na line H$_2$O features. While I absorption not clearly identified, resulting does show very strong potassium feature...
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...
Abstract We used high-precision radial velocity measurements of FGKM stars to determine the occurrence giant planets as a function orbital separation spanning 0.03–30 au. Giant are more prevalent at distances 1–10 au compared orbits interior or exterior this range. The increase in planet ∼1 by factor ∼4 is highly statistically significant. A fall-off larger favored over models with flat increasing occurrence. measure <?CDATA ${14.1}_{-1.8}^{+2.0}$?> <mml:math...
We report 18 years of Doppler shift measurements a nearby star, 55 Cancri, that exhibits strong evidence for five orbiting planets. The four previously reported planets are strongly confirmed here. A fifth planet is presented, with an apparent orbital period 260 days, placing it 0.78 AU from the star in large empty zone between two other velocity wobble amplitude 4.9 m s−1 implies minimum mass Msin i = 45.7 M⊕. eccentricity consistent circular orbit, but modest solutions give similar χ2ν...
view Abstract Citations (332) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Asteroseismology of the DOV Star PG 1159-035 with Whole Earth Telescope Winget, D. E. ; Nather, R. Clemens, J. C. Provencal, Kleinman, S. Bradley, P. A. Wood, M. Claver, F. Frueh, L. Grauer, Hine, B. Hansen, Fontaine, G. Achilleos, N. Wickramasinghe, T. Marar, K. Seetha, Ashoka, O'Donoghue, Warner, Kurtz, W. Buckley, Brickhill, Vauclair, Dolez, Chevreton, Barstow,...
We report Doppler measurements for six nearby G- and K-type main-sequence stars that show multiple low-mass companions, at least one of which has planetary mass. One system three planets, the fourth triple-planet known around a normal star, another an extremely low minimum mass 18 M⊕. HD 128311 (K0 V) two planets (one previously known) with masses (M sin i) 2.18MJ 3.21MJ orbital periods 1.26 2.54 yr, suggesting possible 2 : 1 resonance. For 108874 (G5 V), velocities reveal having ib =...
We present new Spitzer observations of the phase variation hot Jupiter HD 189733b in MIPS 24 μm bandpass, spanning same part planet's orbit as our previous IRAC 8 bandpass (Knutson et al. 2007). find that minimum hemisphere-averaged flux from planet this is 76% ± 3% maximum flux; corresponds to and brightness temperatures 984 48 K 1220 47 K, respectively. The reaches its at an orbital 0.396 0.022, corresponding a region shifted 20°–30° east substellar point. Because tidally locked Jupiters...