Search Publications
Measuring Stellar Radial Velocities with a Dispersed Fixed-Delay Interferometer
Ge, Jian; Mahadevan, Suvrath; Fleming, Scott W. +5 more
We demonstrate the ability to measure precise stellar barycentric radial velocities with the dispersed fixed-delay interferometer technique using the Exoplanet Tracker (ET), an instrument primarily designed for precision differential Doppler velocity measurements using this technique. Our barycentric radial velocities, derived from observations ta…
The Funnel Geometry of Open Flux Tubes in the Low Solar Corona Constrained by O VI and Ne VIII Outflow
Lie-Svendsen, Øystein; Esser, Ruth; Byhring, Hanne S.
We carry out model calculations to show that observed outflow velocities of order 7-10 km s-1 of C IV and O VI ions, and 15-20 km s-1 of Ne VIII ions, are not only consistent with models of the solar wind from coronal holes but also place unique constraints on the degree of flow tube expansion as well as the location of the e…
Analysis of the FUSE Spectrum of the Hot, Evolved Star GD 605
Chayer, P.; Fontaine, G.; Wesemael, F. +2 more
We present an analysis of the atmospheric properties of the evolved, hydrogen-rich object GD 605 using FUSE, IUE, and optical spectra in conjunction with non-LTE (NLTE) model atmospheres and synthetic spectra. We also present an analysis of the interstellar medium along the line of sight toward this star. Our effective temperature determination re…
Cosmic Ray Transport and Production in the Galaxy: A Stochastic Propagation Simulation Approach
Zhang, Ming; Connell, J. J.; Rassoul, Hamid +1 more
Galactic cosmic-ray composition reflects the effects of nuclear interactions during propagation through the interstellar medium. In order to use measurements to determine the source of cosmic rays, one needs a model to deconvolute the propagation effect. This paper presents a new numerical method to solve cosmic-ray diffusive transport equations w…
EA01A/B: High-Resolution H I Imaging of an Interacting Pair of Poststarburst (E+A) Galaxies
Dejonghe, Herwig; De Rijcke, Sven; Buyle, Pieter
We present high spatial resolution 21 cm H I observations of EA01A and EA01B, a pair of interacting poststarburst, or E+A, galaxies at z = 0.0746. Based on optical HST/WFPC2 images, both galaxies are known to display disturbed morphologies. They also appear to be linked by a bridge of stars. Previous H I observations by Chang et al. in 2001 had al…
Nonthermal Electron Measurements in Solar Flares with Hinode EIS
Landi, Enrico; Feldman, Uri; Ralchenko, Yuri
The spectral range of the Hinode EIS (EUV Imaging Spectrometer) instrument is 170-211 Å and 245-291 Å lines emitted by low-energy levels in highly ionized Mn, Fe, Co, and Ni, as well as the very energetic 1s2s3S1-1s2p3P2 transition in Fe XXV, appear in the EIS range. In this paper, we investigate the use…
Observation of Very High Energy Gamma Rays from HESS J1804-216 with CANGAROO-III Telescopes
Katagiri, H.; Edwards, P. G.; Gunji, S. +46 more
We observed the unidentified TeV gamma-ray source HESS J1804-216 with the CANGAROO-III atmospheric Cerenkov telescopes from 2006 May to July. We detected very high energy gamma rays above 600 GeV at the 10 σ level in an effective exposure of 76 hr. We obtained a differential flux of (5.0 +/- 1.5stat+/- 1.6sys) × 10-12
Large-Scale Coronal Density and Abundance Structures and Their Association with Magnetic Field Structure
Raymond, John C.; Riley, Pete; Li, Jing +1 more
We construct subsynoptic maps of the ultraviolet-line fluxes, electron density, and elemental abundances for an east limb corona at 1.63 solar radii from 2000 September 20 to October 1. The data, covering position angles of 85°-126°, were taken from the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SO…
A Search for the Optical Counterpart to the Magnetar CXOU J010043.1-721134
van Kerkwijk, M. H.; Durant, M.
After our tentative detection of an optical counterpart to CXOU J010043.1-721134 from archival Hubble Space Telescope (HST) imaging, we have followed up with further images in four bands. Unfortunately, the source originally identified is not confirmed. We provide deep photometric limits in four bands and accurate photometry of field stars around …
An Overdensity of i-Dropouts among a Population of Excess Field Objects in the Virgo Cluster
Hathi, Nimish P.; Yan, Haojing; Windhorst, Rogier A.
Using a set of deep imaging data obtained by the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) shortly after its deployment, Yan, Windhorst, & Cohen found a large number of F775W-band dropouts (i-dropouts), which are consistent with being galaxies at z ≈ 6. The surface density of i-dropouts thus derived, however, is an …