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Discovery of a Light Echo from SN 2003gd
Sugerman, Ben E. K.
Archival HST/ACS data reveal details of a light echo around SN 2003gd in the galaxy M74, only the fifth supernova around which resolved echoes have been reported. An echo is detected 0.3" from the supernova between position angles of 250° and 360°, with a fainter signal present at a few other position angles. This material lies ~180 pc in front of…
Chemical abundances of very metal-poor stars
Zhao, G.; Zhang, H. W.
High-resolution and high signal-to-noise ratio spectra of 32 very metal-poor stars were obtained with the Coudé echelle spectrograph mounted on the 2.16-m telescope at the National Astronomical Observatories (Xinglong, China). Equivalent widths of FeI, FeII, OI, NaI, MgI, AlI, SiI, SiII, KI, CaI, ScII, TiI, VI, CrI, MnI, NiI, CuI and BaII lines we…
Multi-Wavelength Analysis of High-Energy Electrons in Solar Flares: A Case Study of the August 20, 2002 Flare
Kontar, Eduard P.; Kašparová, Jana; Dennis, Brian R. +2 more
A multi-wavelength spatial and temporal analysis of solar high-energy electrons is conducted using the August 20, 2002 flare of an unusually flat (γ1 = 1.8) hard X-ray spectrum. The flare is studied using RHESSI, Hα, radio, TRACE, and MDI observations with advanced methods and techniques never previously applied in the solar flare conte…
The Ages of Elliptical Galaxies from Mid-Infrared Emission
Brighenti, Fabrizio; Mathews, William G.; Temi, Pasquale
The mid-infrared (10-20 µm) luminosity of elliptical galaxies is dominated by the integrated emission from circumstellar dust in red giant stars. As a single stellar population evolves, the rate of dusty mass loss from red giant stars decreases with time, so the mid-infrared luminosity should also decline with stellar age. To seek such a cor…
The X3 Flare of 2002 July 15
Li, Jing; LaBonte, B. J.; Mickey, D. L.
An X3-class flare occurred on 2002 July 15 with white-light emission and a complex filament eruption. Observations were made in the optical continuum, Hα, UV continuum, microwave, and soft X-rays, as well as with high-cadence longitudinal magnetograms. Within the preflare phase, intense heating is observed accompanying upward motion of the filamen…
Evidence of Correlated Titanium and Deuterium Depletion in the Galactic Interstellar Medium
Tripp, Todd M.; Howk, J. Christopher; Prochaska, Jason X.
Current measurements indicate that the deuterium abundance in diffuse interstellar gas varies spatially by a factor of ~4 among sight lines extending beyond the Local Bubble. One plausible explanation for the scatter is the variable depletion of D onto dust grains. To test this scenario, we have obtained high signal-to-noise, high- resolution prof…
Disk populations from HIPPARCOS kinematic data. Discontinuities in the local velocity distribution
Cubarsi, R.; Alcobé, S.
The full space motions including radial velocities of a stellar sample drawn from HIPPARCOS catalogue are used to discriminate differentiated statistical behaviours that are associated with stellar populations in the solar neighbourhood. A sampling parameter is used to build a hierarchical set of nested samples, where a discontinuous pattern, base…
Hubble Space Telescope WFPC2 Photometry of the Globular Clusters M3 and M13: Binaries and Intrinsic Broadening on the Main Sequence
Bailyn, Charles D.; Zhao, Bing
We study the color-magnitude diagram (CMD) morphologies of M3 and M13 using high-precision Hubble Space Telescope photometry. Asymmetric broadening above and to the red of the main sequence is apparent. We use extensive artificial star experiments to synthetically reproduce chance superposition and photometric error and examine whether a main-sequ…
XMM-Newton 13H deep field - I. X-ray sources
McHardy, I.; Page, M. J.; Seymour, N. +10 more
We present the results of a deep X-ray survey conducted with XMM-Newton, centred on the UK ROSAT13H deep field area. This region covers 0.18 deg2, and is the first of the two areas covered with XMM-Newton as part of an extensive multiwavelength survey designed to study the nature and evolution of the faint X-ray source popula…
Cluster observations of sudden impulses in the magnetotail caused by interplanetary shocks and pressure increases
Balogh, A.; Lucek, E.; Rème, H. +6 more
Sudden impulses (SI) in the tail lobe magnetic field associated with solar wind pressure enhancements are investigated using measurements from Cluster. The magnetic field components during the SIs change in a manner consistent with the assumption that an antisunward moving lateral pressure enhancement compresses the magnetotail axisymmetrically. W…