Search Publications
Transition Region Emission and Energy Input to Thermal Plasma during the Impulsive Phase of Solar Flares
Raymond, John C.; Ciaravella, A.; Kohl, J. +3 more
The energy released in a solar flare is partitioned between thermal and nonthermal particle energy and lost to thermal conduction and radiation over a broad range of wavelengths. It is difficult to determine the conductive losses and the energy radiated at transition region temperatures during the impulsive phases of flares. We use UVCS measuremen…
Is There Enhanced Depletion of Gas-Phase Nitrogen in Moderately Reddened Lines of Sight?
Snow, Theodore P.; Rachford, Brian L.; Jensen, Adam G.
We report on the abundance of interstellar neutral nitrogen (N I) for 30 sight lines, using data from the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telescope (HST). N I column densities are derived by measuring the equivalent widths of several ultraviolet absorption lines and subsequently fitting those to a curve of growth…
Nondetection of Gravitationally Redshifted Absorption Lines in the X-Ray Burst Spectra of GS 1826-24
Kong, Albert K. H.; Miller, Jon M.; Kuulkers, Erik +6 more
During a 200 ks observation with the XMM-Newton Reflection Grating Spectrometer, we detected 16 type I X-ray bursts from GS 1826-24. We combined the burst spectra in an attempt to measure the gravitational redshifts from the surface of the neutron star. We divided the composite GS 1826-24 burst spectrum into three groups based on the blackbody tem…
The Metallicity of Intergalactic Gas in Cosmic Voids
Shull, J. Michael; Danforth, Charles W.; Stocke, John T. +2 more
We have used the Hubble STIS and FUSE archives of ultraviolet spectra of bright AGNs to identify intergalactic Lyα absorbers in nearby (z<=0.1) voids. From a parent sample of 651 Lyα absorbers, we identified 61 ``void absorbers'' located >1.4 h-170 Mpc from the nearest L* or brighter galaxy. Searching for met…
Hubble Ultra Deep Field-JD2: Mid-Infrared Evidence for a z ~ 2 Luminous Infrared Galaxy
Papovich, Casey; Dickinson, Mark E.; Teplitz, Harry I. +5 more
The Hubble Ultra Deep Field source JD2 presented in Mobasher et al. is an unusual galaxy that is very faint at all wavelengths shortward of 1.1 µm. Photometric redshift fits to data between 0.4 and 8 µm yield a significant probability that it is an extremely massive galaxy at z~6.5. In this paper we present new photometry at 16 and 22 …
IGR J08408-4503: A New Recurrent Supergiant Fast X-Ray Transient
Götz, D.; von Kienlin, A.; De Luca, A. +3 more
The supergiant fast X-ray transient IGR J08408-4503 was discovered by INTEGRAL on 2006 May 15 during a bright flare. The source shows sporadic recurrent short bright flares, reaching a peak luminosity of 1036 ergs s-1 within less than 1 hr. The companion star is HD 74194, an Ob5Ib(f) supergiant star located at 3 kpc in the Ve…
The Effects of Polarization Crosstalk and Solar Rotation on Measuring Full-Disk Solar Photospheric Vector Magnetic Fields
Zhang, H. Q.; Su, J. T.
Observations of full-disk solar photospheric vector magnetic fields are very important for the studies of the global properties and evolution of solar magnetism. Such observations can allow us to investigate the magnetic connectivities between active regions and the nonpotentiality of magnetic fields with a much wider field of view (FOV) than do l…
Interstellar Iron and Silicon Depletions in Translucent Sight Lines
Sofia, Ulysses J.; Meyer, David M.; Cartledge, Stefan I. B. +2 more
We report interstellar Fe II and Si II column densities toward six translucent sight lines (AV>~1) observed with the Space Telescope Imaging Spectrograph (STIS). The abundances were determined from the absorption of Si II] at 2335 Å, and several weak Fe transitions including the first reported detections of the λ2234 line. We derive …
On Pitch-Angle Scattering Rates of Interstellar Pickup Ions as Determined by in Situ Measurement of Velocity Distributions
Bochsler, Peter; Möbius, Eberhard; Saul, Lukas +1 more
Newly ionized interstellar atoms are acted upon by electromagnetic forces in the solar wind. Measurements of these pickup ions enable study of the transport processes controlling the evolution of charged particle populations in solar wind plasma. Data from the CELIAS instruments on board the SOHO spacecraft allow measurement of the velocity distri…
Carbonates in Space: The Challenge of Low-Temperature Data
Mutschke, H.; Henning, Th.; Posch, Th. +1 more
Carbonates have repeatedly been discussed as possible carriers of stardust emission bands. However, the band assignments proposed so far were mainly based on room-temperature powder transmission spectra of the respective minerals. Since very cold calcite grains have been claimed to be present in protostars and in planetary nebulae (PNs) such as NG…