Search Publications
Hubble Space Telescope-NICMOS Observations of M31'S Metal-Rich Globular Clusters and Their Surrounding Fields. I. Techniques
Rich, R. Michael; Jablonka, Pascale; Frogel, Jay A. +6 more
Astronomers are always anxious to push their observations to the limit-basing results on objects at the detection threshold, spectral features barely stronger than the noise, or photometry in very crowded regions. In this paper we present a careful analysis of photometry in crowded regions and show how image blending affects the results and interp…
Center-to-Limb Angle Dependence of Phases (v, δ|B|) Observed with the Michelson Doppler Imager
Liu, Y.; Ulrich, R. K.; Norton, A. A.
We test the hypothesis that phases between line-of-sight magnetic and velocity signals depend upon center-to-limb angle if the magnetic response to photospheric velocity perturbations is both magneto-acoustic and Alfvénic. The Michelson Doppler Imager observes two bipolar active regions. Sunspots exhibit the predicted shift toward phase angles of …
Stars with the Largest Hipparcos Photometric Amplitudes
Adelman, Saul J.
A list of the 2027 stars that have the largest photometric amplitudes in Hipparcos Photometry shows that most variable stars are all Miras. The percentage of variable types change as a function of amplitude. This compilation should also be of value to photometrists looking for relatively unstudied, but large amplitude stars.
The Accretion Disk and White Dwarf in the U Geminorum type Dwarf Novae UZ Serpentis and SS Aurigae during Quiescence
Sion, Edward M.; Lake, Joshua
We have carried out high-gravity model atmosphere and accretion disk synthetic spectral fits for the U Geminorum type dwarf novae during quiescence. For UZ Ser, we find that the far-UV spectrum is best fitted with a logg=8, Teff=27,000 K photosphere with abundances near solar. The best-fit accretion disk model for UZ Ser has Mwd
Eclipsing binaries with candidate CP stars. II. Parameters of the system V392 Carinae
North, P.; Debernardi, Y.
We present a detailed study of an eclipsing binary which had been classified Ap SrCrEu (Hartoog \cite{hart}) before being known as a binary. Radial velocities measured at the times of both quadratures allow us to obtain precise masses for both components, while the light curve yields the radii. The following ephemeris and fundamental parameters of…
Wave normal and Poynting vector calculations using the Cassini radio and plasma wave instrument
Gurnett, D. A.; Hospodarsky, G. B.; Kurth, W. S. +4 more
Wave normal and Poynting vector measurements from the Cassini radio and plasma wave instrument (RPWS) are used to examine the propagation characteristics of various plasma waves during the Earth flyby on August 18, 1999. Using the five-channel waveform receiver (WFR), the wave normal vector is determined using the Means method for a lightning-indu…
Photometric Modeling of the Epsilon Ring of Uranus and Its Spacing of Particles
Karkoschka, Erich
The ring model of Irvine (1966, J. Geophys. Res.71, 2931-2937) is used to explain the longitudinal brightness variation of the ɛ ring of Uranus observed by Voyager 2 and with the Hubble Space Telescope, while basic ring properties are based on occultation data. The observations span a factor of 600 in the range of phase angles (0.03-20°) which all…
Models of the Shoemaker-Levy 9 Impacts. I. Ballistic Monte Carlo Plume
Deming, Drake; Harrington, Joseph
We model the plumes raised by impacting fragments of comet Shoemaker-Levy 9 to calculate synthetic plume views, atmospheric infall fluxes, and debris patterns. Our plume is a swarm of ballistic particles with one of several mass-velocity distributions (MVDs). The swarm is ejected instantaneously and uniformly into a cone from its apex. On falling …
Correlation of solar wind parameters between SOHO and Wind
Lazarus, A. J.; Coplan, M. A.; Ogilvie, K. W. +3 more
We describe and interpret new results obtained by correlating measurements of solar wind speed, density, and flux made by the plasma instruments on the SOHO and Wind spacecraft at separations between +/-150 Earth radii (RE) in the Y (GSE) direction and up to 280 RE in the X (GSE) direction. These measurements cover the period…
HST and ground-based observations of the gravitational lens system Q1009-0252 A & B
Surdej, J.; Sluse, D.; Claeskens, J. -F. +2 more
In this paper, we propose a critical study of direct images and spectra obtained for the doubly imaged QSO Q1009-0252 A & B (=LBQS1009-0252 A & B). First, we report new observations with the WFPC2 onboard the Hubble Space Telescope (HST), in which the lensing galaxy is very clearly detected. We combine these with existing NICMOS observatio…