Search Publications
Modeling the Shock Aftermath Source of Energetic Particles in the Solar Corona
Vainio, Rami; Kocharov, Leon; Torsti, Jarmo +2 more
Recent observations on board the Solar and Heliospheric Observatory (SOHO) indicate that acceleration of solar energetic particles (SEPs) at intermediate scales in the solar corona, between flare acceleration and interplanetary CME-driven shock acceleration, significantly contributes to the production of >10 MeV protons. Coronal shocks seem to …
The Discovery of Extended Thermal X-Ray Emission from PKS 2152-699: Evidence for a ``Jet-Cloud'' Interaction
Bechtold, Jill; Ly, Chun; De Young, David S.
A Chandra ACIS-S observation of PKS 2152-699 reveals thermal emission from a diffuse region around the core and a hotspot located 10" northeast from the core. This is the first detection of thermal X-ray radiation on kiloparsec scales from an extragalactic radio source. Two other hotspots located 47" north-northeast and 26" southwest from the core…
X-Rays from Hybrid Stars
Ayres, Thomas R.
The late-type giants and supergiants of the ``hybrid chromosphere'' class display signatures of cool (T<~2×104 K) winds together with hot emission lines from species like C IV (T~105 K). A survey of such stars by Reimers et al. using ROSAT reported numerous X-ray detections (T~106 K), strengthening the (then her…
Galaxy Evolution Explorer Ultraviolet Spectroscopy and Deep Imaging of Luminous Infrared Galaxies in the European Large-Area ISO Survey S1 Field
Buat, Véronique; Burgarella, Denis; Heckman, Timothy M. +23 more
The European Large-Area ISO Survey (ELAIS) S1 field was observed by the Galaxy Evolution Explorer (GALEX) in both its Wide Spectroscopic and Deep Imaging Survey modes. This field was previously observed by the Infrared Space Observatory, and we made use of the catalog of multiwavelength data published by the ELAIS consortium to select galaxies com…
Blue Stragglers in Low-Luminosity Star Clusters
Sandquist, Eric L.
We examine the blue straggler populations of 13 low-luminosity (MVt>~-6) globular clusters and two old open clusters. These clusters test blue straggler formation in environments intermediate between higher luminosity (and usually higher density) clusters and the Galactic field. The anticorrelation between the relative fre…
Direct Evidence for an Early Reionization of the Universe?
Panagia, N.; Stern, D.; Dickinson, M. +5 more
We examine the possible reionization of the intergalactic medium by the source UDF 033238.7-274839.8 (hereafter HUDF-JD2), which was discovered in deep HST/VLT/Spitzer images obtained as part of the Great Observatories Origins Deep Survey and Hubble Ultra Deep Field projects. Mobasher et al. have identified HUDF-JD2 as a massive (~6×1011
Comparison of Solar Cycle Variations of Solar p-Mode Frequencies from GONG and MDI
Chou, Dean-Yi; Serebryanskiy, Alexander
The solar p-mode frequencies change with the solar cycle. The horizontal phase velocity dependence of the relative frequency change scaled by mode mass provides depth information on the perturbations in the solar interior. Both GONG data and SOHO MDI data show that the horizontal phase velocity dependence of the scaled relative frequency change va…
A Chandra Observation of the Nearby Lenticular Galaxy NGC 5102: Where are the X-Ray Binaries?
Ponman, T. J.; Jones, C.; Kraft, R. P. +2 more
We present results from a 34 ks Chandra ACIS-S observation of the low-mass X-ray binary (LMXB) population and the hot interstellar medium (ISM) in the nearby (d=3.1 Mpc) lenticular galaxy NGC 5102, previously shown to have an unusually low X-ray luminosity. We detect 11 X-ray point sources within the D25 optical boundary of the galaxy (…
Deep Photometry of the Globular Cluster M5: Distance Estimates from White Dwarf and Main-Sequence Stars
Sarajedini, Ata; Layden, Andrew C.; Cool, Adrienne M. +1 more
We present deep VI photometry of stars in the globular cluster M5 (NGC 5904) based on images taken with the Hubble Space Telescope. The resulting color-magnitude diagram reaches below V~27 mag, revealing the upper 2-3 mag of the white dwarf cooling sequence and main-sequence stars 8 mag and more below the turnoff. We fit the main sequence to subdw…
A Study of Flare-associated X-Ray Plasma Ejections. III. Kinematic Properties
Cho, K. -S.; Moon, Y. -J.; Park, Y. D. +2 more
In this study, we have investigated the kinematic properties of flare-associated X-ray plasma ejections. First, we obtained the speed profiles of well-observed several events and compared them with the GOES soft X-ray flux profiles as well as the HXT hard X-ray flux profiles of their associated flares. Second, we have estimated the Alfvén speed at…