Search Publications
Perpendicular Transport of Solar Energetic Particles in Heliospheric Magnetic Fields
McKibben, R. B.; Zhang, Ming; Jokipii, J. R.
This paper presents direct observational evidence for large perpendicular diffusive flows of solar energetic particles in heliospheric magnetic fields. Using anisotropy measurements of 40-92 MeV protons obtained by the High-Energy Telescope of the COSPIN consortium on Ulysses at high heliographic latitudes, we find that during several gradual sola…
Simulation of energetic particle injections associated with a substorm on August 27, 2001
Baker, D. N.; Sarris, T. E.; Peterson, W. K. +2 more
Discrete injections of energetic electrons and ions and their subsequent drift echoes were observed shortly after 0410 UT on August 27, 2001 by three geosynchronous satellites which were arrayed on the dayside. The GOES-8 spacecraft at geosynchronous orbit near local midnight, the four-satellite CLUSTER constellation also near local midnight. Conc…
RR Lyrae stars in four globular clusters in the Fornax dwarf galaxy
Mackey, A. D.; Gilmore, G. F.
We have surveyed four of the globular clusters in the Fornax dwarf galaxy (clusters 1, 2, 3 and 5) for RR Lyrae stars, using archival F555W and F814W Hubble Space Telescope observations. We identify 197 new RR Lyrae stars in these four clusters, and 13 additional candidate horizontal-branch variable stars. Although somewhat restricted by our short…
Disentangling microlensing and differential extinction in the double QSO HE 0512-3329
Lopez, S.; Wisotzki, L.; Wucknitz, O. +1 more
We present the first separate spectra of both components of the small-separation double QSO
Hot Gas in the Circumstellar Bubble S308
Guerrero, Martín A.; Chu, You-Hua; Gruendl, Robert A. +2 more
S308 is a circumstellar bubble blown by the WN4 star HD 50896. It is one of the only two single-star bubbles that show detectable diffuse X-ray emission. We have obtained XMM-Newton EPIC observations of the northwest quadrant of S308. The diffuse X-ray emission shows a limb-brightened morphology, with a clear gap extending from the outer edge of t…
Hubble Space Telescope observations of globular cluster systems along the Hubble sequence of spiral galaxies
Strader, Jay; Minniti, Dante; Kissler-Patig, Markus +3 more
We have studied the globular cluster systems of seven giant, edge-on spiral galaxies using Hubble Space Telescope imaging in V and I. The galaxy sample covers the Hubble types Sa to Sc, allowing us to study the variation of the properties of globular cluster systems along the Hubble sequence. The photometry reaches ~1.5 mag beyond the turn-over ma…
Evidence for an Intermediate-Age, Metal-rich Population of Globular Clusters in NGC 4365
Forbes, Duncan A.; Brodie, Jean P.; Beasley, Michael A. +4 more
We present spectroscopy for globular clusters (GCs) in the elliptical galaxy NGC 4365, obtained with the Low-Resolution Imaging Spectrograph on the Keck I telescope. Previous studies have shown that the optical color distribution of GCs in NGC 4365 lacks the bimodal structure that is common in globular cluster systems, showing only a single broad …
Mass limits for the progenitor star of supernova 2001du and other Type II-P supernovae
Smartt, S. J.; Benetti, S.; Maund, J. R. +3 more
The supernova SN 2001du was discovered in the galaxy NGC 1365 at a distance of 19+/-2Mpc, and is a core-collapse event of Type II-P. Images of this galaxy, of moderate depth, have been taken with the Hubble Space Telescope approximately 6.6 yr before discovery and include the supernova position on the WFPC2 field of view. We have observed the supe…
Spectroscopic characteristics of polar plumes
Mason, H. E.; Del Zanna, G.; Bromage, B. J. I.
Extreme ultraviolet observations of plumes in polar coronal holes are presented and their spectroscopic signatures discussed. The study focuses on the base of plumes seen on the disk of the Sun with the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) satellite. Spectroscopic diagnostic techniques are applied …
The HELLAS2XMM survey. III. Multiwavelength observations of hard X-ray selected sources in the PKS 0312-77 field
Maiolino, R.; Perola, G. C.; Fiore, F. +11 more
We present extensive optical, radio and infrared follow-up observations of a sample of 35 hard X-ray (2-10 keV) selected sources discovered serendipitously in the PV XMM-Newton observation of the radio-loud quasar PKS 0312-77 field, for which also an archival Chandra observation is available. The observations have been carried out as part of the H…