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Chandra Localizations and Spectra of INTEGRAL Sources in the Galactic Plane
Kaaret, Philip; Walter, Roland; Tomsick, John A. +2 more
We report on the results of observations of hard X-ray sources in the Galactic plane with the Chandra X-Ray Observatory. The hard X-ray "IGR" sources were discovered by the INTEGRAL satellite, and the goals of the Chandra observations are to provide subarcsecond localizations to obtain optical and infrared counterparts and to provide constraints o…
Luminosity Indicators in the Ultraviolet Spectra of Type Ia Supernovae
Filippenko, Alexei V.; Foley, Ryan J.; Jha, Saurabh W.
We present a complete sample of International Ultraviolet Explorer and Hubble Space Telescope ultraviolet (UV) spectra of Type Ia supernovae (SNe Ia) through 2004. We measure the equivalent width (EW) and blueshifted velocity of the minimum of the one strong UV feature, Fe II λ3250. We also quantify the slope of the near-UV spectra using a new par…
The evolution of planetary nebulae. V. The diffuse X-ray emission
Steffen, M.; Schönberner, D.; Warmuth, A.
Context: Observations with space-borne X-ray telescopes revealed the existence of soft, diffuse X-ray emission from the inner regions of planetary nebulae. Although the existing images support the idea that this emission arises from the hot shocked central-star wind which fills the inner cavity of a planetary nebula, existing models have difficult…
X-ray spectra from magnetar candidates - II. Resonant cross-sections for electron-photon scattering in the relativistic regime
Zane, S.; Nobili, L.; Turolla, R.
Recent models of spectral formation in magnetars called renewed attention on electron-photon scattering in the presence of ultrastrong magnetic fields. Investigations presented so far mainly focused on mildly relativistic particles and magnetic scattering was treated in the non-relativistic (Thomson) limit. This allows for consistent spectral calc…
Models of solar irradiance variations: Current status
Solanki, Sami K.; Krivova, Natalie A.
Regular monitoring of solar irradiance has been carried out since 1978 to show that solar total and spectral irradiance varies at different time scales. Whereas variations on time scales of minutes to hours are due to solar oscillations and granulation, variations on longer time scales are driven by the evolution of the solar surface magnetic fiel…
Stellar Exotica in 47 Tucanae
Zurek, David R.; Shara, Michael M.; Long, Knox S. +3 more
We present far-ultraviolet (FUV) spectroscopy obtained with HST for 48 blue objects in the core of 47 Tuc. Based on their position in a FUV-optical color-magnitude diagram, these were expected to include cataclysmic variables (CVs), blue stragglers (BSs), white dwarfs (WDs), and other exotic objects. For a subset of these sources, we also construc…
Mobile lid convection beneath Enceladus' south polar terrain
Barr, Amy C.
Enceladus' south polar region has a large heat flux, 55-110 mW m-2, that is spatially associated with cryovolcanic and tectonic activity. Tidal dissipation and vigorous convection in the underlying ice shell are possible sources of heat, however, prior predictions of the heat flux carried by stagnant lid convection range from F con…
The 2008 May burst activation of SGR1627-41
Sakamoto, T.; Tiengo, A.; de Luca, A. +16 more
In 2008 May, the soft gamma-ray repeater (SGR) SGR1627-41 resumed its bursting activity after nearly a decade of quiescence. After detection of a bright burst, Swift pointed its X-ray telescope in the direction of the source in less than five hours and followed it for over five weeks. In this Letter, we present an analysis of the data from these S…
Low-mass X-ray binaries in the bulge of the Milky Way
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +4 more
We study the population of low-mass X-ray binaries (LMXBs) in the Galactic bulge using the deep survey of this region by the IBIS telescope aboard the INTEGRAL observatory. Thanks to the increased sensitivity with respect to previous surveys of this field, we succeeded in probing the luminosity function (LF) of LMXBs down to ~7×1034 erg…
Transient layers in the topside ionosphere of Mars
Gurnett, D. A.; Morgan, D. D.; Kopf, A. J. +1 more
Radar soundings from the MARSIS instrument on board the Mars Express spacecraft have shown that distinct layers can occur in the topside ionosphere of Mars, well above the main photo-ionization layer. These layers appear as cusps, or sometimes steps, in plots of the time delay as a function of frequency. Usually only one topside layer is observed,…