Search Publications
The Blue Straggler Population of the Globular Cluster M5: Comparison with M3
Warren, Steven R.; Bolte, Michael; Sandquist, Eric L.
We have surveyed the blue straggler star population of the Galactic globular cluster M5 using high-resolution images of the core along with wide-field ground-based images reaching to more than 19 core radii. To gauge M5's relative efficiency of producing stragglers, we compared our sample to five studies of other globular clusters. Using a ``brigh…
Temporal and Spatial Relationships between Ultraviolet and Hard X-Ray Emission in Solar Flares
Alexander, David; Coyner, Aaron J.
Hard X-ray and ultraviolet emissions in solar flares provide evidence for the interaction of particles accelerated in the solar corona with the ambient plasma in the chromosphere. Previous studies have shown that these emissions are temporally correlated indicating a common source, presumably magnetic reconnection, governing the flare energy relea…
The Narrow-Line Region of the Seyfert 2 Galaxy Mrk 78: An Infrared View
Pérez García, A. M.; Acosta-Pulido, J. A.; Ramos Almeida, C. +3 more
We report near-infrared spectroscopic data for the Seyfert 2 galaxy Mrk 78, taken with the LIRIS near-infrared camera/spectrometer at the William Herschel Telescope (WHT). The long-slit spectra clearly show extended emission. The resolution and depth of the near-infrared spectra allow the examination of its morphology and ionization regions, and a…
Spitzer Observations of V838 Monocerotis: Detection of a Rare Infrared Light Echo
Banerjee, D. P. K.; Misselt, K. A.; Su, K. Y. L. +1 more
We present Spitzer observations of the unusual variable V838 Monocerotis. Extended emission is detected around the object at 24, 70, and 160 µm. The extended infrared emission is strongly correlated spatially with the HST optical light echo images taken at a similar epoch. We attribute this diffuse nebulosity to an infrared light echo caused…
Multiwavelength Observations of the BL Lacertae Object PKS 2155-304 with XMM-Newton
Maraschi, L.; Treves, A.; Celotti, A. +3 more
The optical/UV and X-ray instruments on board XMM-Newton provide an excellent opportunity to perform simultaneous observations of violently variable objects over a broad wavelength range. The UV- and X-ray-bright BL Lac object PKS 2155-304 has been observed repeatedly with XMM-Newton about twice per year. In this paper, we present a detailed analy…
The Formation Epoch of Early-Type Galaxies in the z ~ 0.9 Cl 1604 Supercluster
Ford, H. C.; Demarco, R.; Menanteau, F. +12 more
We analyze the cluster color-magnitude relation (CMR) for early-type galaxies in two of the richer clusters in the z~0.9 supercluster system to derive average ages and formation redshifts for the early-type galaxy population. Both clusters were observed with the Advanced Camera for Surveys on board the Hubble Space Telescope through the F606W and …
Evidence of a High Carbon Abundance in the Local Interstellar Cloud
Slavin, Jonathan D.; Frisch, Priscilla C.
The nature of the local interstellar cloud (LIC) is highly constrained by the combination of in situ heliospheric and line-of-sight data toward nearby stars. We present a new interpretation of the LIC components of the absorption-line data toward ɛ CMa, based on recent atomic data that include new rates for the Mg+ to Mg0 die…
The Nature of Weak Mg II Absorbing Structures
Charlton, Jane C.; Masiero, Joseph R.; Rigby, Jane R. +3 more
We consider geometries and physical models for weak low-ionization absorbers based on the relative incidence of low- and high-ionization systems. We present a survey of weak low-ionization systems in 35 high-resolution HST STIS quasar spectra, sometimes supplemented by Keck HIRES and HST FOS data. We found 16 metal-line systems, with low- and/or h…
Plasma Diagnostics of the Large-Scale Corona with SUMER. I. Measurements at the West Limb
Landi, E.; Doschek, G. A.; Feldman, U.
In the present work we analyze the physical properties of the quiet-Sun plasma measured in a 0.5×1.8 Rsolar region above the west solar limb (Rsolar=solar radius). We make use of large scans obtained with the SUMER spectrometer on board SOHO to construct two-dimensional spatial maps of line intensities, electron temperature, …
037-B327 in M31: Luminous Globular Cluster or Core of a Former Dwarf Spheroidal Companion to M31?
Zhou, Xu; van den Bergh, Sidney; Ma, Jun +6 more
The cluster 037-B327 is of interest because it is both the most luminous and the most highly reddened cluster known in M31. Deep observations with the Advanced Camera for Surveys on the Hubble Space Telescope provide photometric data in the F606W band and also show that this cluster is crossed by a dust lane. We have determined the structural para…