Search Publications
First Stereoscopic Coronal Loop Reconstructions from STEREO SECCHI Images
Solanki, S. K.; Feng, L.; Inhester, B. +4 more
We present the first reconstruction of the three-dimensional shape of magnetic loops in an active region from two different vantage points based on simultaneously recorded images. The images were taken by the two EUVI telescopes of the SECCHI instrument on board the recently launched STEREO spacecraft when the heliocentric separation of the two sp…
The ERO Host Galaxy of GRB 020127: Implications for the Metallicity of GRB Progenitors
Berger, E.; Djorgovski, S. G.; Frail, D. A. +2 more
We present optical and near-IR observations of the host galaxy of GRB 020127, for which we measure R-Ks=6.2 mag. This is only the second GRB host to date classified as an ERO. The spectral energy distribution (SED) is typical of a dusty starburst galaxy, with a redshift z~1.9, a luminosity L~5L*, and an inferred stellar mass of M*<…
Effects of Downscattering on the Continuum and Line Spectra in a Powerful Wind Environment: Monte Carlo Simulations, Analytical Results, and Data Analysis
Laurent, Philippe; Titarchuk, Lev
In an earlier paper, the general formulation and results for photon reprocessing (downscattering) that included recoil and Comptonization effects due to divergence of the flow were presented. In a second paper we showed the Monte Carlo (MC) simulated continuum and line spectra. We also provided an analytical description of the simulated continuum …
Galactic Bulges from Hubble Space Telescope NICMOS Observations: Global Scaling Relations
Balcells, Marc; Graham, Alister W.; Peletier, Reynier F.
We investigate bulge and disk scaling relations using a volume-corrected sample of early- to intermediate-type disk galaxies in which, importantly, the biasing flux from additional nuclear components has been modeled and removed. Structural parameters are obtained from a seeing-convolved, bulge + disk + nuclear-component decomposition applied to n…
The Extended Star Formation History of the Andromeda Spheroid at 21 kpc on the Minor Axis
Ferguson, Henry C.; Brown, Thomas M.; Gilbert, Karoline M. +8 more
Using the Hubble Space Telescope Advanced Camera for Surveys, we have obtained deep optical images of a southeast minor-axis field in the Andromeda galaxy, 21 kpc from the nucleus. In both star counts and metallicity, this field represents a transition zone between the metal-rich, highly disturbed inner spheroid that dominates within 15 kpc and th…
A Statistical Study of Shear Motion of the Footpoints in Two-Ribbon Flares
Golub, Leon; Su, Yingna; Van Ballegooijen, Adriaan A.
We present a statistical investigation of shear motion of the ultraviolet (UV) or extreme-ultraviolet (EUV) footpoints in two-ribbon flares, using the high spatial resolution data obtained in 1998-2005 by TRACE. To do this study, we have selected 50 well-observed X and M class two-ribbon flares as our sample. All 50 of these flares are classified …
The Radio-Coronal Mass Ejection Event on 2001 April 15
Maia, Dalmiro Jorge Filipe; Gama, Ricardo; Mercier, Claude +3 more
On 2001 April 15, the Nançay radioheliograph observed fast-moving, expanding loops in images taken in the wavelength range between 164 and 432 MHz. We were able to follow the progression of the radio loops, starting from a few tenths to more than 1 Rsolar above the solar limb, with a time cadence of order seconds. The loops seen in radi…
Hubble Space Telescope Survey of Interstellar 12CO/13CO in the Solar Neighborhood
Gredel, R.; Lambert, D. L.; Federman, S. R. +2 more
We examine 20 diffuse and translucent Galactic sight lines and extract the column densities of the 12CO and 13CO isotopologues from their ultraviolet A-X absorption bands detected in archival Space Telescope Imaging Spectrograph data with λ/Δλ>=46,000. Five more targets with Goddard High-Resolution Spectrograph data are ad…
Gravitational Shear, Flexion, and Strong Lensing in Abell 1689
Massey, Richard; Goldberg, David M.; Leonard, Adrienne +1 more
We present a gravitational lensing analysis of the galaxy cluster Abell 1689, incorporating measurements of the weak shear, flexion, and strong lensing induced in background galaxies. This is the first time that a shapelet technique has been used to reconstruct the distribution of mass in this cluster and the first time that a flexion signal has b…
Spectroscopy of z ~ 6 i-Dropout Galaxies: Frequency of Lyα Emission and the Sizes of Lyα-emitting Galaxies1,
Rosati, P.; van der Wel, A.; Bouwens, R. J. +8 more
We report on deep spectroscopy, using LRIS on Keck I and FORS2 on the VLT, of a sample of 22 candidate z~6 Lyman break galaxies (LBGs) selected by the i775-z850>1.3 dropout criterion. Redshifts could be measured for eight objects. These redshifts are all in the range z=5.5-6.1, confirming the efficiency of the i775