Search Publications
Spherical harmonic analysis of particle velocity distribution function: Comparison of moments and anisotropies using Cluster data
Gurgiolo, Chris; Viñas, Adolfo F.
This paper presents a spherical harmonic analysis of the plasma velocity distribution function using high-angular, energy, and time resolution Cluster data obtained from the PEACE spectrometer instrument to demonstrate how this analysis models the particle distribution function and its moments and anisotropies. The results show that spherical harm…
The decay phase of solar energetic particle events
Kecskeméty, K.; Daibog, E. I.; Logachev, Y. I. +1 more
The shape of the particle flux profile in the decay phase of solar energetic particle (SEP) events is of particular importance in understanding the propagation of energetic particles in the interplanetary medium. The majority of few-MeV proton events (>90%) exhibit exponential law declines, suggesting the dominant role of convection transport a…
A New Trend in Forecasting Solar Radiation Hazards
Heber, Bernd; Posner, Arik; Guetersloh, Stephen +1 more
Several international space agencies plan to send astronauts beyond low-Earth orbit in the coming decades to explore the Moon or other nearby planetary objects. Humans leaving the Earth's magnetosphere enter the solar wind, potentially exposing themselves to prompt solar energetic particle (SEP) events, which are sudden outbursts of energetic part…
SMEI direct, 3-D-reconstruction sky maps, and volumetric analyses, and their comparison with SOHO and STEREO observations
Jackson, B. V.; Buffington, A.; Hick, P. P. +2 more
In this paper we present the results of the analysis of the late January 2007 Coronal Mass Ejection (CME) events recorded by the Solar Mass Ejection Imager (SMEI), the Solar TErrestrial RElations Observatory (STEREO), and the SOlar and Heliospheric Observatory (SOHO) spacecraft. This period occurs when the two STEREO spacecraft views are from clos…
On oscillations found in an active region with EIS on Hinode
Doyle, J. G.; O'Shea, E.
Aims: Using temporal series (40'' slot) data in the ion{Fe}{xii} 195 Å line from the extreme-ultraviolet imaging spectrometer (EIS) on board the Hinode satellite, we seek to carry out a statistical study of oscillations in an active region.
Methods: Using wavelet techniques, we measure the frequency and duration of oscillations found in the ti…
A Hubble Space Telescope View of the Interstellar Environments of Young Stellar Objects in the Large Magellanic Cloud
Chu, You-Hua; Gruendl, Robert A.; Looney, Leslie W. +2 more
We have used archival Hubble Space Telecope (HST) Hα images to study the immediate environments of massive and intermediate-mass young stellar object (YSO) candidates in the Large Magellanic Cloud (LMC). The sample of YSO candidates, taken from Gruendl & Chu, was selected based on Spitzer IRAC and MIPS observations of the entire LMC and comple…
X-Ray Spectroscopy of the Classical Nova V458 Vulpeculae with Suzaku
Drake, Jeremy J.; Tsujimoto, Masahiro; Ness, Jan-Uwe +2 more
We conducted a target of opportunity X-ray observation of the classical nova V458 Vulpeculae 88d after the explosion using the Suzaku satellite. With a ∼20ks exposure, the X-ray Imaging Spectrometer detected X-ray emission significantly harder than typical super-soft source emission. The X-ray spectrum shows Kα lines from N, Ne, Mg, Si, and S, and…
The Crab pulsar and its pulsar-wind nebula in the optical and infrared
Lundqvist, P.; Tziamtzis, A.; Djupvik, A. A.
Aims. We investigate the emission mechanism and evolution of pulsars that are associated with supernova remnants.
Methods: We used imaging techniques in both the optical and near infrared, using images with very good seeing (≤0.primeprime6) to study the immediate surroundings of the Crab pulsar. In the case of the infrared, we took …
No Neutron Star Companion to the Lowest Mass SDSS White Dwarf
Anderson, Scott F.; Heinke, Craig; Kilic, Mukremin +6 more
SDSS J091709.55+463821.8 (hereafter J0917+4638) is the lowest surface gravity white dwarf (WD) currently known, with log g = 5.55 ± 0.05 (M ≈ 0.17 M sun). Such low-mass white dwarfs (LMWDs) are believed to originate in binaries that evolve into WD/WD or WD/neutron star (NS) systems. An optical search for J0917+4638's companion showed th…
A possible generation mechanism of interplanetary rotational discontinuities
Lin, C. C.; Lee, L. C.; Tsai, C. L. +3 more
In the present paper, we first examine some interplanetary directional discontinuities with very small B n /B (<0.1) using intraspacecraft timing method. It is found that the velocity and magnetic field fluctuations of these directional discontinuities satisfy the Walén relation. We suggest that these directional discontinuities are…