A5080855009- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Solar Radiation and Photovoltaics
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Geomagnetism and Paleomagnetism Studies
- Ionosphere and magnetosphere dynamics
- Atmospheric Ozone and Climate
- Geophysics and Sensor Technology
- Advanced Frequency and Time Standards
- Astronomical Observations and Instrumentation
- Advanced Fiber Laser Technologies
- Inertial Sensor and Navigation
- Advanced Fiber Optic Sensors
- Historical Astronomy and Related Studies
- Calibration and Measurement Techniques
- Optical Systems and Laser Technology
- Surface Roughness and Optical Measurements
- Solar Thermal and Photovoltaic Systems
- Machine Fault Diagnosis Techniques
- Climate variability and models
- Reservoir Engineering and Simulation Methods
Center for Astrophysics Harvard & Smithsonian
2008-2024
Harvard University
1998-2010
Harvard University Press
2005
Smithsonian Astrophysical Observatory
1997-2005
Crimean Astrophysical Observatory
1996
California Institute of Technology
1990-1993
University of California, Los Angeles
1987-1991
University of Southern California
1991
University of California, Santa Barbara
1991
University of California System
1990-1991
The splitting of the frequencies global resonant acoustic modes Sun by large-scale flows and rotation permits study variation angular velocity Ω with both radius latitude within turbulent convection zone deeper radiative interior. nearly uninterrupted Doppler imaging observations, provided Solar Oscillations Investigation (SOI) using Michelson Imager (MDI) on Heliospheric Observatory (SOHO) spacecraft positioned at L1 Lagrangian point in continuous sunlight, yield oscillation power spectra...
Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within solar interior. The nearly uninterrupted observations Global Oscillation Network Group (GONG) yield power spectra high duty cycles signal-to-noise ratios. Frequency splittings derived from GONG confirm that variation rate seen at surface carries through much convection zone, base which is an adjustment layer leading latitudinally...
The bright F8 V star υ Andromedae was previously reported to have a 4.6 day Doppler velocity periodicity, consistent with having Jupiter-mass companion orbiting at 0.059 AU. Follow-up observations by both the Lick and Advanced Fiber-Optic Echelle spectrometer (AFOE) planet survey programs confirm this periodicity reveal additional periodicities 241 1267 days. These are Keplerian orbital motion imply two companions 0.83 2.5 AU, minimum (M sin i) masses of 2.0 MJUP, respectively. Non-Keplerian...
We have used high-cadence radial velocity (RV) measurements from the Hobby-Eberly Telescope with existing velocities Lick, Elodie, Harlan J. Smith, and Whipple 60'' telescopes combined astrometric data Hubble Space Fine Guidance Sensors to refine orbital parameters determine inclinations position angles of ascending node components υ And A c d. With these using M* = 1.31M☉ as a primary mass, we actual masses two companions: is 13.98+2.3−5.3 MJUP, d 10.25+0.7−3.3 MJUP. These represent first...
We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5d of science operations, reveal high signal-to-noise solar-like oscillation spectra in all stars: About 20 modes may be clearly distinguished each star. discuss appearance spectra, use frequencies and frequency separations to provide radii, masses ages stars, comment light these prospects for inference other solar-type stars that will observe.
The planet orbiting τ Boo at a separation of 0.046 AU could produce reflected light flux as bright 1 × 10-4 relative to that the star. A spectrum system will contain component which varies in amplitude and Doppler shift orbits Assuming secondary is primarily stellar spectrum, we can limit be less than 5 10-5. This implies an upper 0.3 for planetary geometric albedo near 480 nm, assuming radius 1.2 RJup. significantly any giant planets solar not consistent with certain published theoretical...
We report the discovery of near-sinusoidal radial velocity variations G0V star ρ CrB, with period 39.6 days and amplitude 67 m s-1. These are consistent existence an orbital companion in a circular orbit. Adopting mass 1.0 M☉ for primary, has minimum about 1.1 Jupiter masses radius 0.23 AU. Such is too large tidal circularization initially eccentric orbit during lifetime star, hence we suggest that low eccentricity primordial, as would be expected planet formed dissipative circumstellar disk.
The Global Oscillation Network Group (GONG) project estimates the frequencies, amplitudes, and linewidths of more than 250,000 acoustic resonances sun from data sets lasting 36 days. frequency resolution a single set is 0.321 microhertz. For frequencies averaged over azimuthal order m , median formal error 0.044 microhertz, associated fractional 1.6 × 10 −5 . 3-year set, expected to be 3 −6 GONG -averaged measurements differ other helioseismic by 0.03 0.08 differences arise combination...
We report new spectroscopic and photometric observations of the parent stars recently discovered transiting planets TrES-3 TrES-4. A detailed abundance analysis based on high-resolution spectra yields [Fe/H] $= -0.19\pm 0.08$, $T_\mathrm{eff} = 5650\pm 75$ K, $\log g 4.4\pm 0.1$ for TrES-3, +0.14\pm 0.09$, 6200\pm 4.0\pm0.1$ The accuracy effective temperatures is supported by a number independent consistency checks. orbital solution improved with our radial-velocity measurements that system,...
We present an analysis of three years precision radial velocity measurements 160 metal-poor stars observed with HIRES on the Keck 1 telescope. report variability and long-term trends for each star in our sample. identify several long-term, low-amplitude radial-velocity variables worthy follow-up direct imaging techniques. place lower limits detectable companion mass as a function orbital period. Our survey would have detected, 99.5% confidence level, over 95% all companions low-eccentricity...
We deployed two wavelength calibrators based on laser frequency combs ("astro-combs") at an astronomical telescope.One astrocomb operated over a 100 nm band in the deep red (∼ 800 nm) and second 20 blue 400 nm).We used these astro-combs to calibrate high-resolution astrophysical spectrograph integrated with 1.5 m telescope, demonstrated calibration precision stability sufficient enable detection of changes stellar radial velocity < 1 m/s.
view Abstract Citations (109) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS What We Know about the Sun's Internal Rotation from Solar Oscillations Goode, Philip R. ; Dziembowski, W. A. Korzennik, S. G. Rhodes, E. J., Jr. In this paper, a uniform approach of inversion was used to determine internal rotation rate sun each six available sets solar oscillation data, which included data Duvall et al. (1986), Rhodes (1987, 1990), Tomczyk (1988),...
The characteristics of the solar acoustic spectrum are such that mode lifetimes get shorter and spatial leaks closer in frequency as degree a increases for given order. A direct consequence this property is individual p-modes resolved only at low intermediate degrees high modes blend into ridges. Once have blended ridges, power distribution ridge defines central frequency, it will mask true underlying frequency. An accurate model amplitude peaks contribute to needed recover from fitting...
The Advanced Fiber Optic Echelle (AFOE) is a fiber-fed echelle spectrograph designed for the measurement of stellar Doppler shifts. Using 2k x CCD detector, it samples about 55% wavelength range between 450 nm and 700 (20 orders) at single shot, with spectral resolution R = 32000 to 70000 500 nm, depending on slit width employed. AFOE employs number devices assure that calibrations necessary accurate measurements can be properly performed. most important these are: (1) coupling telescope via...
view Abstract Citations (51) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Depth and Latitude Dependence of the Solar Internal Angular Velocity Rhodes, Edward J., Jr. ; Cacciani, Alessandro Korzennik, Sylvain Tomczyk, Steven Ulrich, Roger K. Woodard, Martin F. One design goals for dedicated helioseismology observing state located at Mount Wilson Observatory was measurement internal solar rotation using p-mode oscillations. In this paper,...
We demonstrate a tunable laser frequency comb operating near 420 nm with mode spacing of 20-50 GHz, usable bandwidth 15 and output power per line ~20 nW.Using the TRES spectrograph at Fred Lawrence Whipple Observatory, we characterize this system to an accuracy below 1m/s, suitable for calibrating high-resolution astrophysical spectrographs used, e.g., in exoplanet studies.
We describe a high-precision Doppler search for giant planets orbiting well-defined sample of metal-poor dwarfs in the field. This experiment constitutes fundamental test theoretical predictions which will help discriminate between proposed planet formation and migration models. present here details on survey as well an overall assessment quality our measurements, making use results stars that show no significant velocity variation.
We have on hand some 25 years of nearly uninterrupted high-quality and high-cadence global helioseismic data. The Global Oscillations Network Group (GONG) project has been producing science quality data since 1995, the Michelson Doppler Imager (MDI) started in 1996, Helioseismic Magnetic (HMI) took over 2010. Fundamental new constraints imposed by inferences, yet helioseismology processing seems somewhat frozen time for its methodologies. I review discuss specific aspects analysis, with an...
The stars 51 Pegasi and τ Bootis show radial velocity variations that have been interpreted as resulting from companions with roughly Jovian mass orbital periods of a few days. Gray & Hatzes reported the signal Peg is synchronous in shape line λ6253 Fe I; thus, they argue arises not companion planetary but dynamic processes atmosphere star, possibly nonradial pulsations. Here we seek confirming evidence for or strength both Boo, using R = 50,000 observations taken Advanced Fiber Optic...
As a part of an on-going program to explore the signature p-modes in solar-like stars by means high-resolution absorption line spectroscopy, we have studied four (α CMi, η Cas A, ζ Her A and β Vir). We present here new results from two-site observations Procyon acquired over twelve nights 1999. Oscillation frequencies for 0 (or 2) are detected power spectra these Doppler shift measurements. frequency analysis points out difficulties classical asymptotic theory representing p-mode spectrum A.
Spectroscopic observations of 51 Pegasi and τ Bootis show no periodic changes in the shapes their line profiles; these results for Peg are significant conflict with those reported by Gray & Hatzes. Our detection limits small enough to rule out nonradial pulsations as cause variability Boo, but not Peg. The absence shape is consistent stars' radial velocity arising from planetary mass companions.
The solar rotation profile is well constrained down to about 0.25 R thanks the study of acoustic modes. Since radius inner turning point a resonant mode inversely proportional ratio its frequency degree, only low-degree p modes reach core. higher order these modes, deeper they penetrate into Sun and thus carry more diagnostic information on regions. Unfortunately, estimates splittings at high from Sun-as-a-star measurements have observational errors due blending, resulting in weaker...