Search Publications
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…
Is There a High-Energy Particle Population in the Quiet Solar Corona?
Doschek, G. A.; Feldman, U.; Ralchenko, Yu.
A study of spectra emitted by the quiet solar corona indicates that the majority of line intensities originating in low-lying levels are consistent with isothermal plasma of ~1.3×106 K. Nevertheless, a number of line intensities and, in particular, those belonging to ions that are typical of higher temperatures are brighter than expecte…
Search for Electron-Positron Annihilation Radiation from the Jet in 3C 120
McHardy, Ian M.; Agudo, Iván; Jorstad, Svetlana G. +3 more
We report an attempt to detect the electron-positron annihilation line from the radio galaxy 3C 120, in which the jet interacts strongly with interstellar clouds. Such interactions should cause most of the jet plasma to mix with the gas in the clouds. This will thermalize the majority of any positrons in the jet, leading to continuous annihilation…
Near- to Mid-Infrared Spectroscopy for the Giant Elliptical Galaxy NGC 1316 (Fornax A) with the AKARI Infrared Camera
Onaka, T.; Sakon, I.; Kaneda, H.
We present the near- to mid-infrared (~2.5-13 µm) spectrum of the giant elliptical galaxy NGC 1316 (Fornax A) obtained with the Infrared Camera (IRC) on board AKARI. NGC 1316 is known to have a peculiar polycyclic aromatic hydrocarbon (PAH) emission spectrum with an unusually high ratio of the 11.3 µm to the 7.7 µm emission inten…
RHESSI and Hinode X-Ray Observations of a Partially Occulted Solar Flare
Krucker, Säm; Lin, R. P.; Hannah, I. G.
This Letter presents X-ray observations of a partially limb-occulted solar flare taken by the Reuven Ramaty High-Energy Solar Spectroscopic Imager and the X-ray telescope on board Hinode. Thermal emission originates from a simple loop at the western limb that rises slowly (~7 km s-1) until the flare peak time. Above 18 keV, faint nonthe…
What Determines the Intensity of Solar Flare/CME Events?
Reeves, Katharine K.; Golub, Leon; Su, Yingna +3 more
We present a comprehensive statistical study addressing the question of what determines the intensity of a solar flare and associated coronal mass ejection (CME). For a sample of 18 two-ribbon flares associated with CMEs, we have examined the correlations between the GOES soft X-ray peak flare flux (PFF), the CME speed (VCME) obtained f…
Are High-Redshift Quasars Blurry?
Steinbring, Eric
It has been suggested that the fuzzy nature of spacetime at the Planck scale may cause light waves to lose phase coherence, and if severe enough this could blur images of distant pointlike sources sufficiently that they do not form an Airy pattern at the focal plane of a telescope. Blurring this dramatic has already been observationally ruled out …